ORCID Profile
0000-0002-5023-6148
Current Organisation
UNSW Sydney
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Publisher: Wiley
Date: 07-01-2019
DOI: 10.1002/JBM.B.34301
Publisher: Elsevier BV
Date: 08-2002
Abstract: Matrix metalloproteinases (MMPs), together with their tissue inhibitors (TIMPs), are responsible for the controlled degradation of collagen and other matrix substrates in bone and other tissues. This study evaluated the expression of MMPs and TIMPs in bony remodelling in a bilateral sheep mandible model up to 12 months following lengthening by distraction osteogenesis. Sheep mandibles were harvested 3, 6, 9 or 12 months following lengthening by bilateral mandibular distraction (1 mm/day for 20 days). Undistracted sheep mandibles were used as controls. The tissues underwent routine histology and immunohistochemical staining with monoclonal antibodies specific to MMPs 1-3 and TIMP-1, 2. Matrix and cell staining was assessed using a semi-quantitative analysis. Matrix metalloproteinases and their tissue inhibitors (TIMPs) expression levels were marked at 3 months and decreased thereafter becoming similar to undistracted controls by 12 months. The histologic development of mature lamellar cortical bone was similar to undistracted controls by 9 months following distraction. A temporal expression of MMPs and TIMPs was found in distraction osteogenesis. MMPs and TIMPS may, in part, reflect the state of bony remodelling following mandibular lengthening by distraction osteogenesis. Matrix metalloproteinases and TIMP expression were comparable to undistracted controls by 12 months, suggesting that equilibrium had been achieved and that bony relapse is unlikely.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2016
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.BIOMATERIALS.2013.07.022
Abstract: Clinically, allogeneic bone graft is used extensively because it avoids the donor site morbidity associated with autograft. However, there are concerns over the optimal sterilization method to eliminate immunological risks whilst maintaining the biological efficacy of the graft. This study compared the effect of Supercritical fluid (SCF) treatment and gamma irradiation at 25 kGy on the osteoconductivity of allograft bone in a bilateral critical sized defect rabbit model. Osteoconductivity was evaluated at 2 and 4 weeks using X-ray, CT, histology (qualitative and quantitative) and immunohistochemistry (Alkaline Phosphatase and Cathepsin-K). Both grafts were well tolerated and osteoconductive. At 2 weeks, there was decreased bone volume and density in the gamma irradiated graft compared to the SCF treated graft, corresponding with a greater inflammatory response histologically and increased Cathepsin-K expression. Catabolic activity predominated at 4 weeks, with both grafts undergoing significant resorption and remodeling inside the defect. Alkaline Phosphatase expression was greater in the SCF group at both time points indicative of a more anabolic response. Allograft bone sterilized with either gamma irradiation or SCF treatment was osteoconductive and capable of healing a critical sized tibial defect in a rabbit. Gamma irradiated allografts elicited an acute inflammatory reaction when implanted which may increase the amount of graft resorption compared to the SCF treated bone.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 06-2002
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2016
Publisher: Springer Science and Business Media LLC
Date: 25-05-2014
DOI: 10.1007/S00590-013-1238-6
Abstract: Demineralized bone matrix (DBM) allografts are widely used in orthopaedic clinics. However, the biological impact on its osteoinductivity after its sterilization process by gamma irradiation is not well studied. Furthermore, little is known about the relationship between residual calcium levels on osteoinductivity. We hypothesize that low-dose gamma irradiation retains the osteoinducitivity properties of DBM and causes ectopic bone formation. A randomised animal trial was performed to compare tissue and molecular responses of low-dose (11 kGy) gamma irradiated and non-irradiated human DBM at 6 weeks post-intramuscular implantation using an athymic rat model. In addition, we correlated residual calcium levels and bone formation in gamma irradiated DBM. A modified haematoxylin and eosin stain identified ectopic bony capsules at all implanted sites with no significant difference on the amount of new bone formed between the groups. Statistically significantly lower ratio of alkaline phosphatase expression over tartrate-resistant acid phosphatase and/or cathepsin K expressions was found between the groups. This study found that low-dose gamma irradiated DBM, which provides a sterility assurance level of 10(-6) for bone allografts, retained osteoinductivity but exhibited significantly enhanced osteoclastic activity. Furthermore, this is the first study to find a positive correlation between residual calcium levels and bone formation in gamma irradiated DBM.
Publisher: Wiley
Date: 23-10-2013
DOI: 10.1002/JOR.22251
Publisher: British Editorial Society of Bone & Joint Surgery
Date: 11-2021
DOI: 10.1302/2633-1462.211.BJO-2021-0147.R1
Abstract: This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads. In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. S les were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity. Half of each head size group were then cycled with simulated gait and the other half with gait compression only. Damage was measured by area and maximum linear wear depth. Overall, 36 mm heads had lower corrosion onset load (p = 0.009) and change in open circuit potential (OCP) during simulated gait with (p = 0.006) and without joint movement (p = 0.004). Discontinuing gait’s joint movement decreased corrosion currents (p = 0.042) however, wear testing showed no significant effect of joint movement on taper damage. In addition, 36 mm heads had greater corrosion area (p = 0.050), but no significant difference was found for maximum linear wear depth (p = 0.155). Larger heads are more susceptible to taper corrosion however, not due to frictional torque as hypothesized. An alternative hypothesis of taper flexural rigidity differential is proposed. Further studies are necessary to investigate the clinical significance and underlying mechanism of this finding. Cite this article: Bone Jt Open 2021 (11):1004–1016.
Publisher: Wiley
Date: 12-12-2008
DOI: 10.1002/JBM.B.30989
Abstract: A 1.5 cm unilateral rabbit ulna defect model was performed in 18 adult NZ white rabbits. The defects were filled with a beta-tricalcium phosphate bone graft substitute (JAX TCP). The surgical site in half the animals was treated daily with 20 min of low intensity pulsed ultrasound (LIPUS). Animals were sacrificed at 4 weeks (n = 3 per group) or 12 weeks (n = 6 per group) following surgery for radiographic and histologic endpoints. Radiography revealed some resorption of the JAX TCP by 12 weeks in the control and LIPUS treated groups. LIPUS treatment did not accelerate this resorption. Some new bone formation was noted in the control groups at the defect margins while little bone formed in the center of the defect at 4 and 12 weeks. In contrast, radiographs revealed more new bone at 4 and 12 weeks in the LIPUS treated animals throughout the section. Bone mineral density (DEXA) revealed a statistically significant difference at 4 weeks with LIPUS while no differences were found at 12 weeks. Histology of the LIPUS treated sections demonstrated new woven bone formation on and between the JAX TCP bone graft substitute particles across the defect. VEGF expression was increased with LIPUS treatment at 4 weeks and remained elevated at 12 weeks compared with controls. CBFA-1 expression levels were elevated with LIPUS treatment at both time points. LIPUS treatment increased bone formation in ulna defect healing with a beta-tricalcium phosphate bone graft substitute.
Publisher: Proceedings of the National Academy of Sciences
Date: 19-07-2010
Abstract: Biomaterials can be endowed with biologically instructive properties by changing basic parameters such as elasticity and surface texture. However, translation from in vitro proof of concept to clinical application is largely missing. Porous calcium phosphate ceramics are used to treat small bone defects but in general do not induce stem cell differentiation, which is essential for regenerating large bone defects. Here, we prepared calcium phosphate ceramics with varying physicochemical and structural characteristics. Microporosity correlated to their propensity to stimulate osteogenic differentiation of stem cells in vitro and bone induction in vivo. Implantation in a large bone defect in sheep unequivocally demonstrated that osteoinductive ceramics are equally efficient in bone repair as autologous bone grafts. Our results provide proof of concept for the clinical application of “smart” biomaterials.
Publisher: Wiley
Date: 24-11-2003
DOI: 10.1046/J.1445-2197.2003.T01-7-.X
Abstract: The purpose of the present study is to compare five fixation techniques in shoulder fusion. The most common complications resulting from shoulder fusion, non-union and unacceptable arm position, might reflect a failure to achieve rigid fixation during the surgical procedure. Twenty-five shoulder fusions were carried out on human cadaveric specimens using the following techniques: screw fixation, external fixation, external fixation supplemented with screw fixation, single plate fixation and double plate fixation. Each specimen was tested on a servohydraulic machine to determine stiffness. There was a statistically significant difference in bending and torsional stiffness between all five fixation techniques. Normalized bending (B) and torsional stiffness (T), in descending order, were: double plate (B = 1.00, T = 1.00), single plate (B = 0.77, T = 0.89), external fixation with screws (B = 0.68, T = 0.74), external fixation alone (B = 0.40, T = 0.53), and screws alone (B = 0.13, T = 0.26). The risk of the most common complications resulting from shoulder fusion might be minimized if these biomechanical findings are applied to surgical decision making.
Publisher: Elsevier BV
Date: 05-2005
DOI: 10.1016/J.JHSA.2004.10.014
Abstract: Little data exist comparing the strength of traditional methods of fixation in a flexor digitorum profundus tendon with the use of a suture anchor. In vitro cyclic testing simulating a passive mobilization protocol was used to compare the repair of a flexor digitorum profundus tendon using a single micro-Mitek anchor (Mitek, Westwood, MA) or a modified Bunnell 2-strand pullout technique using a monofilament or a braided polyester suture. Twenty-four fresh-frozen cadaveric fingers were ided randomly into 4 repair groups (n = 6 each): a micro-Mitek with a 3-0 braided polyester suture or a 3-0 monofilament suture, or a modified Bunnell technique with a 3-0 braided polyester suture or a 3-0 monofilament suture. After repair the specimens were loaded cyclically from 2 to 15 N at 5 N/s, for a total of 500 cycles. Gap formation at the tendon-bone interface was assessed every 100 cycles. S les were tested to failure at the completion of 500 cycles. No specimens failed catastrophically during cyclic testing. A significantly greater gap formed using the monofilament sutures compared with the braided polyester sutures with both repair techniques. Load to failure in the modified Bunnell technique was superior to the micro-Mitek with both suture types. The modified Bunnell technique using a braided polyester suture was superior to the monofilament suture whereas the suture type did not alter the properties of the micro-Mitek repair. Significant gap formation with the use of a monofilament suture may be of concern. The use of a braided polyester suture when removal of the pullout suture is required as in the Bunnell technique also needs to be considered.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-03-2015
Publisher: Elsevier BV
Date: 08-2000
Abstract: Total hip arthroplasty for severe chronic proximal femoral migration, most commonly seen in congenital dislocation of the hip, has been associated with high rates of complications. A new technique of femoral subtrochanteric shortening osteotomy with the prosthesis in situ is described. This technique minimizes the potential complications, allows for correction of severe femoral neck anteversion, and gives excellent rotational stability, while preserving the proximal femur for better press-fit cementless fixation. In this series, there were 9 cases: 6 women and 2 men with a mean age of 53 years (range, 26-77 years). The average follow-up period was 56 months (range, 6-86 months). The mean preoperative Harris Hip Score was 31 (range, 20-35), and the mean postoperative score was 81 (range, 60-98). At follow-up, all patients reported significant pain relief and functional improvement. All osteotomies appeared to be healed on radiographs by 12 weeks. There were 3 complications. The first complication was a recurrent dislocation resulting from muscle incompetence, which was revised using a constrained liner and a 32-mm head with no further dislocations. The second complication was a breach of the femoral shaft, which was treated operatively using a longer stem. The third complication was a proximal femoral shaft split, which was treated by leaving the cerclage wire in situ. This technique should be considered in cases of congenital dislocation of the hip and when femoral shortening is needed.
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.ARTHRO.2008.10.026
Abstract: To evaluate the anatomic, biomechanical, and histologic properties of the biceps vinculum and its potential role as a restraint to distal migration of the biceps after tenotomy. Eight human shoulders were dissected to define the anatomic parameters of the biceps vinculum. Histologic studies were performed by sectioning through the vinculum-tendon attachment and performing H&E staining. The strength of the vinculum was tested biomechanically after sectioning the biceps origin and applying a uniaxial tension at a rate of 1 mm/s until failure. With regard to anatomy, the vinculum was present in all specimens, attached to the biceps tendon and proximal humerus. Excursion testing showed that the vinculum prevented the biceps origin from migrating distal to the groove entrance. The mean dimensions of the structures and excursion were as follows: biceps origin to vinculum, 43.4 mm vinculum width on biceps side, 46.2 mm vinculum width on bone side, 69.3 mm length of tendon with proximal pull, 42.6 mm and length of tendon with distal pull, 2.25 mm. With regard to histology, the membranous tissue of the biceps vinculum consisted of loose soft tissue with fat, arteries, and veins. The vinculum was seen to loosely attach to the biceps tendon and more intimately attach to the periosteal/bone side. With regard to biomechanical testing, the maximum force to failure of the vinculum was variable, ranging from 17.4 N to 227.6 N, with a mean value of 102.7 +/- 76 N. The biceps vinculum was a consistent membranous structure intimately associated with the biceps tendon and attached to the proximal humerus. After tenotomy at the biceps origin, the vinculum prevented distal migration of the proximal biceps tendon past the groove entrance in all specimens. Biomechanical testing showed that the vinculum provided variable resistance to distal pull. The properties described may help to explain why biceps tenotomy does not routinely result in a Popeye biceps deformity.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Elsevier BV
Date: 09-1999
DOI: 10.1016/S0021-9290(99)00072-X
Abstract: A computerised, real time, thin-film pressure transducer method is used to measure tibiofemoral contact area in total knee arthroplasty (TKA) devices that is easier and more reliable and reproducible as compared to the Fuji pressure-sensitive film technique. Many authors have suggested that contact areas and pressures within TKA devices can be a predictor of wear and failure of the ultra-high molecular weight polyethylene (UHMWPE) tibial insert. In this study, two contact area measurement techniques (Fuji pressure-sensitive Film and K-scan sensor system) were compared using a custom TKA testing jig designed for freedom of movement so that in any loading configuration the component found and seated in its own "home" position. The K-scan system was used to measure contact areas of one TKA design at several angles from 0 to 110 degrees flexion with loads equating to 4, 4.5, and 5 times body weight. For comparison, four ranges of Fuji film were used to measure areas at the same flexion angles but at 5 times body weight only. Contact areas measured with the Fuji films were 11-36% (p < 0.05) lower than those measured by the K-scan sensor.
Publisher: SAGE Publications
Date: 19-02-2015
Abstract: Multiple-strand repair techniques are commonly used to repair cut flexor tendons to achieve initial biomechanical strength. Looped sutures achieve multiple strands with fewer passes and less technical complexity. Their biomechanical performance in comparison with an equivalent repair using a single-stranded suture is uncertain. This study examined the mechanical properties of double-stranded loops of 3-0 and 4-0 braided polyester (Ticron) and polypropylene monofilament (Prolene). Double loops were generally less than twice the strength of a single loop. Ticron and Prolene had the same strengths, but Ticron was stiffer. The 4-0 double loops had significantly higher stiffness than 3-0 single loops. Increasing the size of sutures had a larger relative effect on strength than using a double-stranded suture. However, a double-strand loop had a larger effect on increasing stiffness than using a single suture of a larger equivalent size. Looped suture repairs should be compared with standard techniques using a thicker single suture.
Publisher: Elsevier BV
Date: 1990
DOI: 10.1016/0021-9290(90)90167-2
Abstract: The conversion of mechanical loads to bioelectrical signals in bone have been suggested to control repair and remodeling. These signals in wet bone are attributed to the electrokinetic behavior where mechanical forces cause electrical signals due to motion of an ion carrying extracellular fluid in the bone matrix (streaming potentials). Streaming potential experiments were performed on control and chemically treated intact wet bone plugs in aphosphate and phosphate buffers to examine the contribution of bone constituents to the electrokinetic behavior of bone tissue. Data indicate that the organic constituents of bone dominate streaming potentials. Slopes of streaming potential vs pressure are related to the electrokinetic (zeta) potential. The slopes should be analyzed in the low pressure region where data is mainly linear. Comparisons of estimated zeta potentials from streaming potentials with existing data obtained by particle electrophoresis showed similar trends.
Publisher: Springer Science and Business Media LLC
Date: 22-11-2009
Publisher: Elsevier BV
Date: 03-2001
Abstract: Laminated tears of the rotator cuff are often lined by a cellular layer that has an appearance suggestive of synovium. This study demonstrates, by histologic and immunohistochemical means, that the lining cells are synovial. It remains unclear whether these cells arise by synovial extension from the joint or bursa, or by metaplasia in the presence of synovial fluid, and this has implications for surgical repair of laminated cuff defects. We suggest that these defects be curetted, to remove at least some of this synovial lining, before suture repair.
Publisher: SAGE Publications
Date: 03-1994
DOI: 10.1177/036354659402200221
Abstract: One hundred twenty-eight skeletally mature New Zea land White rabbits were used to study the effect of a single corticosteroid injection on the biomechanical, biochemical, and histologic aspects of ligamentous healing. Two steroid dosages were used. The amount of the low-dose steroid was calculated by determining the corticosteroid concentration at which fibroblastic synthesis of collagen was inhibited in vitro. A human equivalent dose of betamethasone was used as the high-dose steroid injection. These two steroid doses and a saline control were injected around a transected medial collateral-ligament. At 10 days all groups showed significantly inferior biomechanical properties relative to noninjected controls. By 3 weeks the human equivalent steroid dose group continued to demonstrate signifi cantly inferior properties. Histologic and biochemical analyses confirmed the biomechanical results. The clinical relevance of the study was that the delivery of a human equivalent steroid dose into an acutely injured ligament significantly impairs the healing process rela tive to a noninjected ligament at 10 days and at 3 weeks after injury. This implies that a corticosteroid-treated in jured ligament may not be able to withstand the me chanical loads of early vigorous rehabilitation.
Publisher: Georg Thieme Verlag KG
Date: 20-11-2020
Abstract: Objective Cats rely on their forelimb mobility for everyday activities including climbing and grooming. Supination and pronation of the forelimb in cats are considered to primarily involve the antebrachium, rather than the carpus. Therefore, our null hypothesis was that there would be no movement of the carpal bones (radial carpal bone, ulnar carpal bone and accessory carpal bone) relative to the ulna during supination and pronation. Study Design Eight feline cadaveric forelimbs were rotated from supination to pronation in a jig and computed tomography was performed in the neutral, supinated and pronated positions. The in idual carpal bones were segmented from computed tomography images of the supinated and pronated scans in each of the eight specimens. A feline ulna coordinate system was established and used to quantify the translations and rotations between bones of the proximal carpal row and antebrachium. Results After the carpus was rotated from the initial supinated position into pronation, there was significant translation (x, y and z axes) and rotation (x and y axes) of the proximal row of carpal bones based on absolute magnitude values. Given the differences in translations and rotations of the proximal row of carpal bones, our null hypothesis was rejected. Conclusion The proximal row of carpal bones translate and rotate independently from the ulna in the cat during pronation of the antebrachium. This may have future implications in the diagnosis and management of feline carpal injuries involving the antebrachiocarpal joint.
Publisher: Wiley
Date: 06-1996
Publisher: Wiley
Date: 11-05-2012
DOI: 10.1002/JOR.22141
Abstract: Patella alta is associated with adverse cartilage adaptations, patellofemoral pain, and instability. It is defined by a relatively long patellar tendon and patella positioned in a more proximal location within the patellar groove of the femur. This study used the ovine stifle joint model to investigate the effect of patellar tendon lengthening on the 3D passive kinematics of the patellofemoral and tibiofemoral joints. Eight patellar tendons were lengthened in 2 mm increments up to a maximum of 12 mm (20%) using a device placed in series with the transected patellar tendon. Three-dimensional kinematics were measured in the intact joint and at each increment of patellar tendon length (L(T)) during passively induced tibiofemoral flexion. Patellar flexion angle was linearly correlated with tibial flexion angle in the intact joint, and this correlation persisted after tendon lengthening (R = 0.897-0.965, p 9%. In contrast, when patellofemoral kinematics were expressed as a function of patellar flexion angle they were not significantly altered by increases in L(T). Tibiofemoral kinematics were not affected by the L(T) increases. These results demonstrate that for a given tibial flexion angle, patellar tendon lengthening alters the patellar flexion angle. However, for a given patellar flexion angle, the orientation of the patella in the remaining five degrees of freedom is unchanged, implying a repeatable path of patellar motion.
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ACTBIO.2011.01.017
Abstract: To evaluate moldable osteoinductive putties for bone repair we combined microstructured biphasic calcium phosphate (BCP) particles with five different polymeric gels, carboxymethyl cellulose (CMC), Pluronic(®) F-127 (PLU), polyvinyl alcohol (PVA), chitosan (CHI) and alginate (ALG). In vitro gel dissolution showed that CMC, PLU and ALG gels dissolved rapidly (within hours), while the CHI gel took several days and the PVA gel did not dissolve within 2 weeks. Implanting the putty formulations into sheep muscle for 12 weeks demonstrated ectopic bone formation in the control BCP group as well as the putties prepared with dissolving gels (CMC, PLU, ALG and CHI). Bone was not seen in the putty comprising PVA. Quantitative data showed that the CMC and PLU gels did not significantly affect the osteoinductivity of BCP granules, while the ALG and CHI gels showed a significant decrease in bone formation. These results suggest that the dissolvability and chemistry of the gels may be factors affecting the osteoinduction of the putties.
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.JHSA.2009.12.039
Abstract: The benefit of repairing a 75% partial flexor tendon laceration remains controversial. The purpose of this study was to assess the degree of gap formation with and without repair when the 75% lacerated tendon is subjected to cyclic loading. Repair with only a peripheral suture was compared to that using a core and peripheral repair technique. Sixteen deep flexor tendons from sheep hind limbs were lacerated to 75% of the tendon diameter. The cut tendons were loaded for 100 cycles from 3 N up to 30 N and then back to 3 N, at a rate of 0.2 Hz. Gap formation was measured at 0 and 100 cycles. Tendons were then randomized into 2 repair groups of 8 each: group 1 was repaired with only a simple, running peripheral suture (6-0 polypropylene monofilament), whereas group 2 was repaired with a modified Kessler core suture (4-0 silicone-coated braided polyester) plus a peripheral suture (6-0 polypropylene monofilament). Repaired tendons were tested for 500 cycles, and the gap was measured at 0, 100, and 500 cycles. After cycling, gap was measured at 100 N load, and the peak loads were determined on static failure testing. The 75% partially lacerated tendons had >2 mm gap at 100 cycles. This gap was significantly reduced by peripheral or peripheral plus core repairs (p < .001). There was no difference in gap formation between tendons with peripheral repair only and those with both peripheral and core repairs. Gap formation in repaired tendons remained <or=1 mm at 500 cycles. After cycling, neither gap formation at 100 N load or the peak loads on failure testing differed between the 2 repair groups. There is a large gap when an unrepaired 75% partial laceration is cyclically loaded. This gap is significantly reduced with a peripheral repair whether or not a core suture is used.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2004
DOI: 10.1097/01.BRS.0000092369.50397.85
Abstract: Randomized investigation of multiaxial pedicle screw mechanical properties. Measure static yield and ultimate strengths, yield stiffness, and fatigue resistance according to an established model. Compare these measured properties with expected loads in vivo. Multiaxial pedicle screws provide surgical versatility, but the complexity of their design may reduce their strength and fatigue resistance. There is no published data on the mechanical properties of such screws. Screws were assembled according to a vertebrectomy model for destructive mechanical testing. Groups of five assemblies were tested in static tension and compression and subject to three cyclical loads. Modes of failure, yield, and ultimate strength, yield stiffness, and cycles to failure were determined for six designs of screw. Static compression yield loads ranged from 217.1 to 388.0 N and yield stiffness from 23.7 to 38.0 N/mm. Cycles to failure ranged from 42 x 10(3) to 4,719 x 10(3) at 75% of static ultimate load. There were significant differences between designs in all modes of testing. Failure occurred at the multiaxial link in static and cyclical compression. Bending yield strengths just exceeded loads expected in vivo. Multiaxial designs had lower static bending yield strength than fixed screw designs. Five out of six multiaxial screw designs achieved one million cycles at 200 N in compression bending. "Ball-in-cup" multiaxial locking mechanisms were vulnerable to fatigue failure. Smooth surfaces and thicker material appeared to be protective against fatigue failure.
Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.ARTH.2007.10.023
Abstract: The addition of large amounts of antibiotics to bone cement provides a convenient local delivery, but may influence the compressive properties of the cement. Flucloxacillin and vancomycin were added to Simplex P (Stryker, Limerick, Ireland) and VersaBond (Smith & Nephew) cements. Tripling the antibiotic dose from 2 to 6 g had little effect on the static compressive properties 24 hours after curing. After 4 weeks in phosphate-buffered saline, there was marked decrease in properties with the addition of antibiotics. Compressive strength of cements with 6 g of antibiotic was reduced to near or below the ASTM and ISO minimum of 70 MPa after 4 weeks in phosphate-buffered saline. Microcomputer tomography revealed increased porosity and clumping of the radiopacifier with the addition of antibiotics.
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.ARTHRO.2011.01.010
Abstract: This study examined the viscoelastic properties of 6 common arthroscopic sliding knots (Tennessee slider, Roeder knot, SMC knot, Duncan loop, Weston knot, and Nicky's knot) with 3 reversing half-hitches on alternating posts, tied with No. 2 FiberWire (Arthrex, Naples, FL). Knot configuration was designed to simulate a double-row rotator cuff repair with suture bridges. Constructs were loaded in 20-N increments to 100 N and held for 2 minutes to monitor the viscoelastic behavior in tension. Suture was also tested without tying a knot. Stress relaxation increased with loading but did not differ between knot configurations. Initial elongation was highest during the first loading to 20 N. Relaxation was greater for the Roeder knot at 20 N and for the Roeder and SMC knots at 80 N (P < .05) when compared with the loop with no knot. Elongation was greatest for the Roeder knot throughout all loads. This difference was significant at 60 N compared with the knotless loop. At 100 N, all knots showed greater elongation than the knotless loop (P < .05). Testing of suture, without any knots, accounted for more than 75% of the overall stress relaxation and loop elongation of the suture-knot construct. In our in vitro evaluation of the Tennessee slider, Roeder knot, SMC knot, Duncan loop, Weston knot, and Nicky's knot in a simulated suture bridge construct, knot configuration was not a variable that influenced elongation or stress relaxation. Overall response was primarily due to the suture itself. With the exception of the Roeder knot, relaxation was similar provided that a secure knot was formed at the time of original tying. With the evolution of surgical devices, the reliance on knots is decreasing. The results of this study suggest that using knotless techniques for securing the rotator cuff will not change the stress relaxation characteristics of the suture bridge.
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.MEDENGPHY.2011.11.021
Abstract: Bone is an anisotropic non-homogenous composite material composed of inorganic bone mineral embedded in an organic matrix. The mechanical behaviour of bone is governed by the volume fraction of these constituents, their mechanical properties, the degree of crystallite-collagen orientation and the bonding between phases. This study aims to evaluate the mechanical role of these constituents in the expression of anisotropy by using gamma irradiation to alter the mineralised collagen fibrils. Bovine cortical cubes were prepared, treated and mechanically tested in uniaxial compression in the axial, radial and tangential orientations. Ultimate stress, ultimate strain, energy to failure and stiffness were evaluated. This study confirmed deleterious effect of gamma irradiation on the axial compressive properties of cortical bone with a dose dependent decrease in ultimate stress of 6% (P=0.231) and 16% (P=0.001) at 15 and 25 kGy respectively. This corresponded to a 39% (P=0.058) and 30% (P=0.167) reduction in energy to failure. In the radial orientation there was also a dose dependant decrease in ultimate stress which was consistent with a statistically significant decline in ultimate strain (31% (P=0.003) and 36% (P=0.000)) and energy to failure (36% (P=0.053) and 45% (P=0.008)) at both doses. In the tangential orientation there was a significant 22% (P=0.01) and 23% (P=0.02) decrease in stiffness though these changes did not alter ultimate stress considerably. This study provides valuable insights into the role of collagen in the radial and tangential orientation when loaded in compression while also building on the body of work related to the use of gamma irradiation for load bearing bone allografts.
Publisher: Elsevier BV
Date: 10-2000
Abstract: Distraction osteogenesis is a technique used to lengthen the shortened mandible. However, the long term stability of the distracted mandibular bone is not known. The aim of this study was to assess if the sheep mandible relapses following lengthening, and to assess the quality of distracted bone up to 1 year post lengthening. Twenty-four sheep had bilateral external mandibular distractors applied, with three sheep as controls. Titanium marker screws were positioned both proximal and distal to the distraction zone in all sheep. Following a 5 day latency period, the interdental gap was distracted 1 mm/day for 20 days, with a subsequent 20 day consolidation period. Ante-mortem serial X-rays were used to assess for relapse by measuring the distance between the screws. The animals were sacrificed at either 3, 6, 9 or 12 months post-distraction. At post mortem, the distance between the screws was re-measured. The distracted bone was assessed mechanically and histologically. The mean mandibular lengthening obtained was 13.2 mm. There was no relapse of the mandible over 12 months. The distracted bone had attained the strength and stiffness of undistracted bone by 6 months post-distraction (p < 0.05). Histological evaluation revealed significant amounts of lamellar bone by 6 months post-distraction. No relapse occurred for 12 months post distraction lengthening. The bone formed following distraction was stable and of good quality. These findings lend support to the use of distraction osteogenesis in clinical practice.
Publisher: SAGE Publications
Date: 06-2004
DOI: 10.1016/J.JHSB.2003.12.002
Abstract: Mid-shaft transverse osteotomies were performed in 18 cadaveric metacarpals and randomly ided into two groups. Using dorsally applied plates for repair, one group was secured using 6 mm unicortical screws, while bicortical screws were used in the second group. The metacarpals were tested to failure with a four-point bending protocol using a servo-hydraulic testing machine and a 1 kN load cell. The mean load to failure was 596 N (SD=142) for the unicortical and 541 N (SD=171) for the bicortical group. The stiffness was 333 N/mm (SD=116) for the unicortical and 458 N/mm (SD=158) for the bicortical group. Both load to failure and stiffness were not statistically significant between the two groups. Failure occurred by fracture at the screw-bone interface in all specimens: no screw pull-out was observed. No biomechanical advantage was found when using bicortical screws in metacarpal fracture plating.
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.BIOMATERIALS.2007.09.035
Abstract: The use of artificial bone graft substitutes has increased as the surgical applications widen and the availability of allograft bone decreases. The ideal graft substitute should reabsorb with time to allow and encourage new bone formation whilst maintaining its properties as an osteoconductive scaffold until it is no longer required. A potential disadvantage of some synthetic substitutes is their long dissolution time. Beta-tricalcium phosphates (beta-TCPs) have some advantages when compared to hydroxyapatite (HA), when used as a filler, in that it is more rapidly reabsorbed. Three commercially available and clinically used beta-TCP bone graft substitutes with the same chemistry (Vitoss, Osferion, Chronos) but with varying macro and microscopic characteristics were investigated using a bilateral tibial metaphyseal defect model in New Zealand white rabbits. When placed into tibial defects all three materials performed similarly in terms of mechanical properties of the healing defects. A decrease in properties was found at 12 weeks where implant resorption was nearly achieved while remodelling of the anteromedial cortex had yet to be completed. All materials were osteoconductive and supported new bone formation while implant resorption with time differed between materials. Vitoss resorbed faster than the other materials and is likely to differences in particle geometry, pore structure and interconnectivity.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2012
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.JOCN.2016.05.028
Abstract: Anterior lumbar interbody fusion (ALIF) is a common procedure for patients with degenerative pathologies of the lumbar spine. In this study, the clinical and radiological outcomes of a combination titanium olyetheretherketone (Ti/PEEK) ALIF cages in one, two and three-level surgery were evaluated. Over an 18-month time period, a prospective single surgeon series of 20 implants (15 patients) were included in the study, with minimum 10-months follow-up. From these 15 patients, two were supplemented with posterior percutaneous pedicle screw fixation for additional stability. Radiological follow-up with fine cut CT scan at 9-12months was performed to evaluate early fusion rates, and integration of the Titanium/PEEK cage at the endplate junction. 20 implants were followed for a minimum of 10months, and a mean of 15months. A 95% (19/20 implants) fusion rate with no implant related complications was achieved at the mean 15-month postoperative mark. Patients experienced statistically significant improvement in pain and functional outcomes (SF12 and ODI) compared to their pre-operative status. A single patient with a non-union at L5/S1 (smoker) did not experience any improvement in symptoms. A Ti-PEEK cage, with allograft and BMP-2 to achieve interbody fusion is an effective implant for use in anterior lumbar surgery with high fusion rates, no lucency around the titanium endplates at follow-up, and with promising early results.
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.ARTH.2012.02.025
Abstract: Arthroplasty has evolved with the application of electron beam melting (EBM) in the manufacture of porous mediums for uncemented fixation. Osseointegration of EBM and plasma-sprayed titanium (Ti PS) implant dowels in adult sheep was assessed in graduated cancellous defects and under line-to-line fit in cortical bone. Shear strength and bony ingrowth (EBM) and ongrowth (Ti PS) were assessed after 4 and 12 weeks. Shear strength of EBM exceeded that for Ti PS at 12 weeks (P = .030). Ongrowth achieved by Ti PS in graduated cancellous defects followed a distinctive pattern that correlated to progressively decreasing radial distances between defect and implant, whereas cancellous ingrowth values at 12 weeks for the EBM were not different. Osteoconductive porous structures manufactured using EBM present a viable alternative to traditional surface treatments.
Publisher: Elsevier BV
Date: 05-2003
Publisher: Informa UK Limited
Date: 31-01-2013
Publisher: ASME International
Date: 23-08-2017
DOI: 10.1115/1.4037558
Abstract: Radiographic data, including computed tomography (CT) and planar X-ray, is increasingly used for human and animal kinematic studies. There is a tendency toward using as high-resolution imaging as possible. Higher resolution imaging is one factor (in conjunction with the reconstruction algorithm), which may increase the precision of reconstructed three-dimensional (3D) surface models in representing true bone shape. However, to date no study has tested the effects of scan resolution, threshold, and 3D model reconstruction algorithm on the accuracy of bone kinematic results. The present study uses a novel method to do this where canine tarsal bones were positioned on a radiolucent Lego™ board and scanned before and after undergoing known translations and/or rotations. The digital imaging and communications in medicine (DICOM) images were acquired using two different CT scanning resolutions and processed using three different segmentation threshold levels and three different reconstruction algorithms. Using one bone as the reference bone, an iterative closest point (ICP) algorithm was used to register bones to a global co-ordinate system and allow measurement of other bone kinematics in terms of translations and rotations in and around the x-, y-, and z-axes. The measured kinematics were compared to the “known” kinematics, which were obtained from the Lego™ board's manufacturing standards and tolerances, to give accuracy error metrics for all bones. The results showed error in accuracy of measured kinematics was at subvoxel levels (less than 0.5 mm). Despite altering the volume and surface area of the 3D bone models, variation in resolution, segmentation threshold and reconstruction algorithm had no significant influence upon the accuracy of the calculated tarsal bone kinematics.
Publisher: Springer Science and Business Media LLC
Date: 06-2004
Publisher: Wiley
Date: 16-03-2006
DOI: 10.1002/JBM.B.30527
Abstract: In an adult porcine model, the effectiveness of a bioresorbable film to minimize soft tissue attachment to the pelvic viscera was evaluated at 4-week and 12-week endpoints. Following a transperitoneal laparotomy through a midline incision, the bladder and uterus were abraded in all animals to promote soft tissue attachment to the viscera. Control animals received no further treatment. The experimental group animals were treated with bioresorbable polylactide (PLa) sheets, 0.02 mm thick, one between the bladder and the abdominal wall, and a second sheet between the bladder and the uterus. Quantitative assessment of the severity and location of soft tissue attachments, and qualitative histologic assessment were performed at 4 and 12 weeks post-operatively. Statistically significant differences in the quantitative soft tissue attachment scores were observed in comparing the PLa film treated animals versus the control animals, at both the 4-week and 12-week time points. In the control animals, the formation of numerous thick fibrous bands was observed at both time points. Histology revealed no adverse reaction to the bioresorbable PLa barrier film. The bioresorbable PLa sheet provided an effective barrier between adjacent anatomical structures and minimized soft tissue attachments to the device when in contact with the viscera as compared to the control groups. Surgical dissection planes between the abdominal wall and adjacent soft tissues were maintained with the use of the PLa sheet at both time points.
Publisher: Elsevier BV
Date: 06-2014
Publisher: SAGE Publications
Date: 05-2007
Abstract: Cartilage has an extremely poor capacity to heal, which has lead to intensive research into biomaterials and tissue engineering for the purpose of regenerating cartilage in vivo. Many of these techniques have shown great promise in vitro however, the results do not always carry across to the in-vivo scenario. Healthy cartilage autografts often do not integrate with the adjacent cartilage, suggesting that cartilage is rarely capable of healing even under ideal conditions. It is hypothesized in this study that the surgical creation of defects in cartilage causes significant damage to the adjacent tissues, leading to further degradation of the cartilage and poor outcome for the repair in general. This study compares the healing response of osteochondral defects created with either a punch or a drill in the weight-bearing region of the sheep knee at 4 and 26 weeks following surgery. The use of a drill to create the defect creates a more aggressive inflammatory response at 4 weeks compared with a punch. However, by 26 weeks, defects created with a punch scored higher on the O'Driscoll cartilage grading scale. Tissue damage at the time of surgery plays an important part in the sequence of events for healing of cartilage defects. This knowledge will help to characterize and refine the ovine model for cartilage regeneration and may have an influence on surgical technique and instrumentation for clinical cartilage repair.
Publisher: Elsevier BV
Date: 09-2004
Publisher: Wiley
Date: 09-1991
Abstract: Streaming potential experiments were performed on chemically-treated intact wet bone plugs equilibrated in potential-determining ion buffers. Comparison of calculated zeta (zeta) potentials from intact wet bone streaming potentials and bone particle electrophoresis indicates different values. Intact streaming potential experiments, where fluid is forced through the s les, represents flow, primarily through the vascular channel system, and contribution of the organically-lined channels to the electrokinetic zeta potential. Bone particle electrophoresis represents mainly the electrokinetic contribution of exposed mineralized matrix. The organic linings present in the vascular channel system limit potential-determining ions' access to the mineralized matrix. These linings may have an important role in mineral homeostasis and control of ion fluxes between bone compartments.
Publisher: Elsevier BV
Date: 02-1998
DOI: 10.1016/S1010-5182(98)80034-6
Abstract: The rabbit model has been used to study the effects of different rates of distraction upon mandibular bone. Bilateral distraction was performed at two different rates anterior to the molar teeth. Both experimental groups were significantly inferior to sham operated controls in terms of bone density (DEXA) and mechanical testing. No difference in new bone formation between the two distraction rates was detected by these modalities. However, histological examination revealed non-union to be more common in the rapidly distracted group. This suggests that attempts to shorten the duration of external fixation in clinical mandibular distraction osteogenesis should be by methods other than more rapid distraction.
Publisher: AIP
Date: 2009
DOI: 10.1063/1.3223930
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.INJURY.2013.11.032
Abstract: The maintenance of friction between locking plates and bone is not essential, so that they can be applied with a gap between the plate and underlying bone. We hypothesised that the presence of a gap under a locking plate with a conical coupling mechanism would reduce fixation stability or allow uncoupling of the locking screws from the plate. Locking plates with two conically coupled locking screws were applied to 6 pairs of adult canine femora. One of each pair had plate to bone contact and the contralateral construct had a 2 mm plate to bone gap. Constructs were cyclically loaded in cantilever bending with 10 percent incremental increases every 1000 cycles at 2 Hz, starting at 250 N. The constructs were fatigued to failure. To evaluate fatigue life of the conical coupling, testing was repeated with aluminium tubing replacing the bone, to eliminate screw-bone cutout failure. The mean sustained loads and cycles to failure in the contact group (420.80, standard error [SE] 14.97 N 7612.00, SE 574.70 cycles) were significantly greater than in the gap group (337.50, SE 14.97 N 4252.00, SE 574.70 cycles), (p<0.001). Failure mode of all bone constructs was via screw cutout from the bone. Aluminium tubing constructs failed via screw or plate fatigue and breaking, with one construct having elevation of the plate over the screw head. Elevation of locking plates with a conical coupling system by 2 mm from the bone reduced construct fatigue life but did not result in screw head uncoupling from the plate.
Publisher: Georg Thieme Verlag KG
Date: 2017
Abstract: Objective: To compare the initial biomechanical properties of olecranon osteotomies stabilized with intramedullary pins and a Nitinol bone staple to osteotomies stabilized with pin and tension band wire fixation. Study design: Ex vivo mechanical evaluation on cadaveric bones. Material and methods: Ten pairs of cadaveric forelimbs from skeletally mature Greyhounds with an olecranon osteotomy stabilized with either a pin and Nitinol bone staple or a pin and tension band wire. A single load to failure was applied to each specimen through the triceps tendon. Biomechanical properties were compared based on stiffness, yield load, and maximum load to failure and load at 2 mm of axial displacement. Results: Specimens stabilized with the bone staple were biomechanically superior in all the variables tested. There was significantly greater stiffness (118.0 ± 25.9 N/mm versus 70.1 ± 40.4 N/mm p = 0.005), yield load (319.0 ± 99.8 N versus 238.0 ± 42.5 N p = 0.03), maximum load sustained (385.0 ± 99.2 N versus 287.0 ± 37.4 N p = 0.009), and load at 2 mm of axial displacement (218.0 ± 51.5 N versus 138.0 ± 48.7 N p = 0.002) in specimens stabilized with pins and a Nitinol bone staple than specimens stabilized with pin and tension band wire fixation. Clinical significance: The pin and Nitinol bone staple construct provides a biomechanically superior alternative to pin and tension band wire fixation for stabilization of olecranon osteotomies, and its use warrants further clinical investigation. Supplementary material for this article is available at 0.3415/VCOT-17-02-0025
Publisher: Public Library of Science (PLoS)
Date: 25-08-2015
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.EJVS.2014.12.025
Abstract: This study sought to compare the local tissue response and subsequent volume of intimal hyperplasia (IH) that develops throughout the maturation of an arteriovenous fistula created using continuous/interrupted polypropylene with that of a novel, metal-alloy, penetrating anastomotic clip device. Forty-six fistulae were created in 23 sheep under a paired design using the nitinol U-Clip (n = 23) in one hind limb and continuous (n = 20) or interrupted (n = 3) polypropylene suture for the other. Animals were killed at 4 (n = 3), 14 (n = 3), 28 (n = 10), 42 (n = 3), and 180 (n = 4) days. Histological sections were evaluated for quantitative histology and immunohistochemistry. Compared with continuous polypropylene, U-Clip specimens demonstrated less intima-media area per unit length (IMA/L), proliferating cells, and tissue necrosis at all time points (MANOVA, F = 9.8-24.1, all p ≤ .005 observed power >82%). Specifically, values of IMA/L were reduced by 5% (p = .97), 37% (p = .02), 33% (p < .01), 9% (p = .42), and 14% (p = .22) at the time points of 4, 14, 28, 42, and 180 days respectively. Proliferating cells were reduced by 75% (p < .01), 72% (p = .03), 76% (p = .03), 27% (p = .31), and 60% (p = .01) and tissue necrosis by 67% (p < .01), 58% (p = .02), 40% (p = .33), 21% (p = .43), 77% (p = .11). In a 28-day comparison between U-Clip and interrupted polypropylene the U-Clip group demonstrated a 4% (p = .65) reduction in IMA/L, 74% (p < .01) in proliferating cells and 49% (p < .05) in tissue necrosis. These results provide evidence of reduced local tissue necrosis, proliferating cells, and IH, favouring arteriovenous fistulae created using the U-Clip anastomotic device over conventional polypropylene suture techniques most evident over the first 4 weeks.
Publisher: Elsevier BV
Date: 03-2002
DOI: 10.1016/S1350-4533(01)00124-2
Abstract: The strain distribution imposed on a femur following a total joint replacement is an important factor, in proximal bone loss due to stress shielding, and long term clinical success. This study investigated how five different design parameters of a cementless titanium femoral prosthesis influenced cortical strains. Test loads were applied and strains were measured with and without an abductor force simulation, using six human cadaveric femora. The cementless design used demonstrated significant calcar loading proximally and a similar strain distribution to the intact femur distally. Implant gross geometry was the major factor in determining the cortical strain distributions under abductor simulation in both axial and torsional loading.
Publisher: SAGE Publications
Date: 07-11-2013
Abstract: The Pulvertaft weave has been the standard tendon junction technique used both in tendon transfers and tendon grafts. A limitation of this repair is the sequential failure of stabilizing sutures, rather than the tendon. A novel loop weave is described and compared with the Pulvertaft weave in biomechanical performance. Ovine deep flexor and extensor tendons were used to simulate Pulvertaft or loop weaves ( n = 11) for tensile testing. The Pulvertaft weaves failed at the stabilizing sutures, whereas the loop weaves repairs failed by longitudinal splitting of the motor tendon. The loop weave demonstrated significantly higher mean initial failure and ultimate strengths. Tensile loads required to elongate the loop weave by 4, 6, and 8 mm were significantly higher, while more displacement was associated with the Pulvertaft repair under the application of 50, 75, and 100 N tensile loads. This study demonstrates favourable biomechanical characteristics of the new loop weave technique.
Publisher: MDPI AG
Date: 08-12-2021
DOI: 10.3390/S21248186
Abstract: Advancements in motion sensing technology can potentially allow clinicians to make more accurate range-of-motion (ROM) measurements and informed decisions regarding patient management. The aim of this study was to systematically review and appraise the literature on the reliability of the Kinect, inertial sensors, smartphone applications and digital inclinometers/goniometers to measure shoulder ROM. Eleven databases were screened (MEDLINE, EMBASE, EMCARE, CINAHL, SPORTSDiscus, Compendex, IEEE Xplore, Web of Science, Proquest Science and Technology, Scopus, and PubMed). The methodological quality of the studies was assessed using the consensus-based standards for the selection of health Measurement Instruments (COSMIN) checklist. Reliability assessment used intra-class correlation coefficients (ICCs) and the criteria from Swinkels et al. (2005). Thirty-two studies were included. A total of 24 studies scored “adequate” and 2 scored “very good” for the reliability standards. Only one study scored “very good” and just over half of the studies (18/32) scored “adequate” for the measurement error standards. Good intra-rater reliability (ICC 0.85) and inter-rater reliability (ICC 0.80) was demonstrated with the Kinect, smartphone applications and digital inclinometers. Overall, the Kinect and ambulatory sensor-based human motion tracking devices demonstrate moderate–good levels of intra- and inter-rater reliability to measure shoulder ROM. Future reliability studies should focus on improving study design with larger s le sizes and recommended time intervals between repeated measurements.
Publisher: Mary Ann Liebert Inc
Date: 2011
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 07-2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
DOI: 10.1097/BSD.0B013E3182AA6841
Abstract: In vitro biomechanical laboratory study. The purpose of this study is to evaluate a mechanical treatment to create a degenerative motion segment and the ability of nucleus augmentation to restore biomechanics. In cases with an intact annulus fibrosus, the replacement or augmentation of the nucleus pulposus alone may provide a less invasive option to restore normal biomechanics and disk height when compared with spinal fusion or total disk replacement. Laboratory testing allows these changes to be fully characterized. However, without preexisting pathology, nucleus augmentation therapies are difficult to evaluate in vitro. The present study evaluated pure moment bending and compressive biomechanics in 3 states (n=6): (1) intact, (2) after creep loading and nucleus disruption to induce degenerative biomechanical changes, and (3) after nucleus augmentation through an injectable polymer (DiscCell). Neutral zone and ROM were increased in all modes of bending after the degenerative treatment. The most sensitive mode of bending was lateral bending, with intact ROM (20.0±2.9 degrees) increased to 22.3±2.6 degrees after degenerative treatment and reduced to 18.4±1.6 degrees after injection of the polymer. All bending ROM and NZ changes induced by the degenerative treatment were reversed by nucleus augmentation. This material was shown to be effective at altering motion segment biomechanics and restoring disk height during time zero tests. This technique may provide a model to examine the time zero performance of a nucleus augmentation device/material.
Publisher: Springer Science and Business Media LLC
Date: 03-2008
DOI: 10.1007/S10195-008-0099-Y
Abstract: Increasing the porosity of an antibiotic-loaded cement spacer increases the antibiotic elution, but the correlation between porosity and antibiotic elution is not well documented. The purposes of this study was to attempt new porosity-increasing methods and to investigate the correlation between antibiotic elution and both total and surface porosity. Five types of antibiotic-loaded bone cement (ALBC) using 2 g cefazolin and 40 g cement were prepared. Other than manual mixing, hydrogen peroxide was used as a foaming agent and a mixing drill piece was used as a mechanical device to try to induce porosity when mixing the cement. Elution of antibiotic into phosphate-buffered saline was measured from 1 h to 1 week. Surface porosity was calculated from density values which were measured with a density kit and an electronic balance, while total porosity was quantified using micro-computed tomography. When a mixing drill piece was used to induce porosity, we observed a significant increasin antibiotic elution compared to a manually mixed ALBC. On the other hand, hydrogen peroxide reduced the elution significantly. Mild correlation between the total amount of cluted in 1 week antibiotic elution and total porosity was observed. In terms of improving elution, the mixing drill piece seemed to be efficient. A relationship between surface porosity and elution efficacy was not observed.
Publisher: SAGE Publications
Date: 20-07-2010
Abstract: The aetiology of Kienböck's disease is unknown. Ulnar variance and lunate shape are possible mechanical risk factors. This study assessed the trabecular structure in 29 cadaveric lunates using microCT and correlated this with ulnar variance and lunate shape on plain radiographs and with bone density assessed using conventional CT. The bony trabeculae within the lunate were shown to run almost perpendicular to the proximal and distal joint surfaces in the coronal plane these trabeculae met the subchondral bone at an angle between 72–102°. In lunates whose proximal and distal articular surfaces are not parallel, the trabecular orientation may be less able to resist compressive forces and more susceptible to fracture.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.SPINEE.2018.02.017
Abstract: Increasing bone ongrowth and ingrowth of polyether ether ketone (PEEK) interbody fusion devices has the potential to improve clinical outcomes. This study evaluated the in vivo response of promoting new bone growth and bone apposition with NanoMetalene (NM) compared with PEEK alone in a cancellous implantation site with an empty aperture. This is a randomized control animal study. Implants and funding for this study were provided by SeaSpine (60,000 USD). Cylindrical dowels with two apertures were prepared as PEEK with a sub-micron layer of the titanium (NM). The titanium coating was applied over the entire implant (Group 1) or just the apertures (Group 2). Polyether ether ketone implants with no coating served as controls (Group 3). Implants were placed in the cancellous bone of the distal femur or proximal tibia with no graft material placed in the apertures in eight adult sheep. Bone ongrowth to the surface of the implant and ingrowth into the apertures was assessed at 4 and 8 weeks after surgery with micro-computed tomography (CT) and undecalcified histology. The apertures in the implants were notably empty in the PEEK group at 4 and 8 weeks. In contrast, new bone formation into the apertures was found in s les coated with NM even though no graft material was placed into the defect. The bone growing into the aperture tracked along the titanium layer. Apertures with the titanium coating demonstrated significantly more bone by micro-CT qualitative grading compared with PEEK with average bone coverage scores of Group 1 (NM) 1.62±0.89, Group 2 (NM apertures only) 1.62±0.77, and Group 3 (PEEK) 0.43±0.51, respectively, at 4 weeks (p<.01) and Group 1 (NM) 1.79±1.19, Group 2 (NM apertures only) 1.98±1.18, and Group 3 (PEEK) 0.69±0.87, respectively, at 8 weeks (p<.05). The amount of bone in the apertures (ingrowth) quantified using the volumetric data from the micro-CT supported an overall increase in bone volume inside the apertures with the titanium coating compared with PEEK. Histology showed newly formed woven bone tracked along the surface of the titanium in the apertures. The PEEK interface presented the typical nonreactive fibrous tissue inside the apertures at 4 weeks and some focal contact with bone on the outside at 4 weeks and 8 weeks. Micro-CT and histology demonstrated bone ongrowth to the surfaces coated with NM where the newly formed bone tracked along the thin titanium-coated surfaces. Polyether ether ketone surfaces presented the nonreactive fibrous tissue at the interface as previously reported in preclinical scenarios.
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.JSE.2008.01.143
Abstract: The surgical treatment of chronic acromioclavicular injuries remains controversial. There is increasing use of autogenous tendon grafts to perform these reconstructions. This study examined the mechanical properties of differing configurations of these grafts. Mechanical testing of acromioclavicular joint reconstructions was performed with a screw and soft tissue washer for tendon fixation, a simple loop of tendon tied to itself, and a bio-interference screw for tendon fixation, with and without a loop of nonabsorbable suture for reinforcement. The bio-interference screw fixation, with reinforcement by a loop of nonabsorbable suture, gave the highest load to failure among the group (502N +/- 177), which was not significantly different from the intact ligaments (705 N +/- 132), although it was significantly less stiff than the intact group (57.2 N/mm +/- 12.6 and 109.7 N/mm +/- 32.6, respectively). All other reconstructions had an ultimate load and stiffness which were significantly less than that of the intact specimens.
Publisher: SAGE Publications
Date: 20-10-2020
Abstract: The aim of this study was to investigate total hip arthroplasty (THA) Morse taper pull-off strengths after impaction prior to cyclical loading compared to cyclical loading alone. The practical relevance of the experiment is to provide a perspective on what may be clinically satisfactory taper assembly given the spectrum of head tapping patterns used by surgeons, as well as compare traditional impaction performed in standard THA with alternate methods of taper engagement such as ‘ in situ assembly’ used in micro-invasive techniques. 36 taper constructs utilising a combination of cobalt-chrome alloy and ceramic-titanium alloy junctions were investigated in vitro in wet and dry conditions with cyclical loading of the constructs. Taper disengagement strengths with and without impaction were compared. Secondary investigation of the surface roughness of the heads and tapers was also assessed. An impaction to a wet taper resulted in a greater pull off force compared to a dry taper with a CoCr head and taper combination. Impacting the head and dryness of the taper did not affect pull off forces of a ceramic femoral head on titanium taper. Pulling a head off a taper significantly alters the head surface roughness. Impaction of a taper does not provide any benefit over cyclical loading of a taper assembly alone for pull-off strength.
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.ARTH.2010.12.007
Abstract: Porous scaffold dowels of Ti(6)Al(4)V were prepared and implanted into cancellous and cortical bone sites in adult sheep. Cancellous implants were examined under gap, line-to-line, and press-fit conditions, whereas line-to-line implantation was used in cortical sites. Cortical shear strength increased significantly with time and reached 26.1 ± 8.6 MPa at 12 weeks, accompanied by a concomitant increase in bone integration and remodeling. In cancellous sites, bone integration was well established at 4 and 12 weeks under conditions of press-fit and line-to-line match between implant and surgical defect. New bone growth was also found in the gap conditions, although to a lesser extent. These findings suggest that the porous Ti(6)Al(4)V could prove an effective scaffold material for uncemented fixation in cortical and cancellous sites.
Publisher: Springer Berlin Heidelberg
Date: 2008
Publisher: MDPI AG
Date: 09-07-2022
DOI: 10.3390/MA15144805
Abstract: Corrosion of medical implants is a possible failure mode via induced local inflammatory effects, systemic deposition and corrosion related mechanical failure. Cyclic potentiodynamic polarisation (CPP) testing was utilized to evaluate the effect of increased porosity (60% and 80%) and decreased wall thickness in gyroid lattice structures on the electrochemical behaviour of LPBF Ti6Al4V structures. The use of CPP allowed for the landmarks of breakdown potential, resting potential and vertex potential to be analysed, as well as facilitating the construction of Tafel plots and qualitative Goldberg analysis. The results indicated that 60% gyroid s les were most susceptible to the onset of pitting corrosion when compared to 80% gyroid and solid s les. This was shown through decreased breakdown and vertex potentials and were found to correlate to increased lattice surface area to void volume ratio. Tafel plots indicated that despite the earlier onset of pitting corrosion, both gyroid test groups displayed lower rates of corrosion per year, indicating a lower severity of corrosion. This study highlighted inherent tradeoffs between lattice optimisation and corrosion behaviour with a potential parabolic link between void volume, surface area and corrosion being identified. This potential link is supported by 60% gyroid s les having the lowest breakdown potentials, but investigation into other porosity ranges is suggested to support the hypothesis. All 3D printed materials studied here showed breakdown potentials higher than ASTM F2129′s suggestion of 800 mV for evaluation within the physiological environment, indicating that under static conditions pitting and crevice corrosion should not initiate within the body.
Publisher: Wiley
Date: 10-2003
DOI: 10.1046/J.1445-2197.2003.02790.X
Abstract: Diagnostic ultrasound examination has become the most commonly used investigation in Australia for diagnosing rotator cuff tears. The authors felt that the results of such investigations were often inaccurate in their clinical practices. The diagnostic ultrasound findings in 336 cases were compared to arthrography, and in 225 cases findings at surgery. A very poor accuracy rate of 0.38 was found for diagnostic ultrasound examination. The sensitivity was 0.24 and specificity was 0.61. Extreme caution is recommended in the use of diagnostic ultrasound, as currently practised in a general community setting, in diagnosing full-thickness rotator cuff tears.
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.BJPS.2009.02.066
Abstract: Reconstruction of cutaneous nasal defects is often a challenging problem with multiple solutions. Many factors must be considered when deciding on the appropriate reconstructive procedure, including optimally matching donor site skin to the original recipient site skin. To the best of our knowledge no objective study has been undertaken to examine which areas best match the histological features of skin from various nasal cosmetic subunits. We have undertaken a descriptive histological analysis of skin from 25 facial and nasal aesthetic subunits from four male Caucasian cadavers, aged 65-88. The three variables looked at were epidermal thickness, dermal thickness and density of pilosebaceous subunits. Our findings have been plotted on photographs of the face to provide visual maps of facial histological features by cosmetic subunit. Our results show that histologically, the best matched skin for reconstructing a given nasal defect is likely to come from an adjacent nasal subunit. Looking at distant donor sites, the helical root, helical rim and pre-auricular area are closest to nasal skin in terms of dermal thickness. In terms of density of pilosebaceous units, the helical root, pre-auricular area and lateral forehead are the three areas best matched to nasal skin.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.CLINBIOMECH.2010.02.007
Abstract: Drilling of bone is associated with an increase in temperature of the surrounding bone which may result in osteonecrosis. In this study, cutting efficiency and thermal properties of one 2-fluted drill and two 3-fluted drills were determined in vitro using a porcine model. Drills were then used to create pilot holes in an in vivo ovine model to facilitate implantation of pedicle screws. The effect of the characteristic thermal profiles of each drill on cortical bone cell viability and screw pull-out strength was then assessed. Cutting efficiencies of both 3-fluted designs were found to be greater than that of the 2-fluted drill, but this did not translate into a decrease in the maximum temperatures during drilling for both drills. Histologically, no empty osteocyte lacunae were seen at 2 or 4 weeks, suggesting that temperatures were not sufficiently high enough to induce thermonecrosis in the ovine tibia. No differences were found in the pull-out strength of the screws. Both 2- and 3-fluted drills are currently in clinical use. Despite the theoretical advantage that 3-fluted drills possess over their 2-fluted counterparts, there is a lack of evidence in the literature in support of their use. In this study the observed increases in cutting efficiency of the 3-fluted drills tested did not translate into a reduction in heat generation or improvement in bone healing or screw fixation.
Publisher: Medical Journals Sweden AB
Date: 2008
DOI: 10.1080/17453670810016920
Abstract: Current specifications (standards) for preclinical testing of bone cements (ISO 5833: 2002, ASTM F451-99a) require simple mechanical testing after ageing for 24 h under dry conditions at 23 degrees C. Some bone cements have fulfilled the requirements in the specifications, and yet had inferior clinical results. Clinically, bone cements are subjected to complex loading patterns in a moist or wet environment at 37 degrees C. Thus, both the validity and the robustness of current standard testing protocols can be questioned. We examined the influence of temperature and storage medium on the properties of bone cement. We also compared the results of storage and testing under standard conditions of 23 degrees C in dry air, with the results obtained at 37 degrees C in water or plasma. The dry specimens showed an increase in strength and elastic modulus with time, while the values of the wet ones decreased. There was no difference between specimens stored in water or in plasma. Ultimate compressive strength of dry specimens after 24 h was 1.16 times higher than that of the ones stored wet, increasing to 1.34 times after 1 month, and 1.46 times after 6 months (p<0.001 for all comparisons). Testing under dry conditions-as required in current standards-always gave higher values for mechanical properties than did storage and testing under more physiological conditions. The sensitivity of test values to different environments implies that testing conditions for bone cements should be scrutinized in order to develop more relevant testing protocols that reflect the in vivo environment more closely.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.BJPS.2016.12.004
Abstract: Spring-assisted cranioplasty (SAC) has become an accepted treatment for patients with sagittal craniosynostosis however, the early effects of springs on skull dimensions have never been assessed with objective measurements in the literature. The present study evaluated the changes in skull dimensions and intracranial volume (ICV) during the first 3 months after SAC for sagittal synostosis. Sixteen patients with sagittal synostosis underwent SAC. The cephalic index (CI) and the distance between the spring foot plates were chronologically measured until spring removal at 3 months. Pre- and post-treatment CT scans available for 6 patients were used to assess changes in head shape. Thirteen patients underwent objective aesthetic assessment using pre- and post-operative photographs. Statistical analysis was performed using the linear mixed model for chronological data, t-test statistics for normative data comparisons and Wilcoxon's signed rank test for non-parametric data. For scaphocephalic patients, pre-operative and post-operative CIs were 0.70 and 0.74 (p = 0.001), respectively. Cranial widening towards normative values was observed (p = 0.0005). A continuous expansion in the distance between the spring foot plates was observed over the treatment period. Frontal and occipital angles were not affected by SAC despite apparent clinical improvements in frontal bossing and occipital prominence. CT analysis demonstrated relative reduction in the anterior cranial volume (p = 0.01) and relative expansion of the superior occipital volume (p = 0.03). Spring expansion was most marked in the hours following spring insertion. The expansion rate reduced to the minimum by day 1 post-operatively. Clinical benefits of SAC resulted from an increase in the bi-temporal width that camouflaged the frontal bossing. Improvement in occipital prominence was due to superior occipital volume expansion, allowing the occiput to remodel to a more rounded shape.
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.JCMS.2005.07.003
Abstract: Lengthening the mandible by distraction osteogenesis (DO) is nowadays a well recognized technique in maxillofacial surgery. In this study growth factor expression profiles were examined in biopsies taken from six patients undergoing mandibular DO and compared with findings from a sheep model for mandibular DO. In all patients (and sheep), the ascending ramus was distracted 10-15 mm at a rate of 1mm/day using an intraoral device. Biopsies were taken from the centre of the distraction zone 21 days after completion of distraction. Using standard immunohistochemical techniques, s les were stained for platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF) and bone morphogenetic proteins-2, -4 and -7 (BMP-2, -4, -7), matrix metalloproteinases-1 and -3 (MMP-1, -3), the vascular endothelial growth factor (VEGF), a marker for endothelial cells (CD-31) and type IV collagen (Col IV). Positive staining for PDGF, bFGF, TGF-beta, BMP-2, -4, and -7 was noted in cells and matrix components. There was intense staining for MMP-1. Strong staining for CD-31 and COL IV was observed adjacent to vessels. VEGF staining was less specific. Similar findings were noted in the sheep model. Growth factor expression in the human distraction site is similar to that in the sheep model.
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.ACTBIO.2009.09.016
Abstract: Implant heating has been advocated as a means to alter the porosity of the bone cement/implant interface however, little is known about the influence on cement properties. This study investigates the mechanical properties and pore distribution of 10 commercially available cements cured in molds at 20, 37, 40 and 50 degrees Celsius. Although each cement reacted differently to the curing environments, the most prevalent trend was increased mechanical properties when cured at 50 degrees Celsius vs. room temperature. Pores were shown to gather near the surface of cooler molds and near the center in warmer molds for all cement brands. Pore size was also influenced. Small pores were more often present in cements cured at cooler temperatures, with higher-temperature molds producing more large pores. The mechanical properties of all cements were above the minimum regulatory standards. This work shows the influence of curing temperature on cement properties and porosity characteristics, and supports the practice of heating cemented implants to influence interfacial porosity.
Publisher: Springer Science and Business Media LLC
Date: 02-1994
DOI: 10.1007/BF00121694
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.JSE.2004.03.006
Abstract: The high recurrence rate associated with anterior shoulder dislocations may reflect inadequate healing of a Bankart lesion when the arm is immobilized in internal rotation. The effect of external rotation (ER) of the humerus on the glenoid-labrum contact of Bankart lesions was examined in 10 human cadaveric shoulders. The contact force between the glenoid labrum and the glenoid was measured in 60 degrees of internal rotation, neutral rotation, and 45 degrees of ER in 10 human cadaveric shoulders. No detectable contact force was found with the arm in internal rotation. The contact force increased as the arm passed through neutral rotation and reached a maximum at 45 degrees of ER. The contact force returned to 0 g when the arm was returned to neutral rotation. The mean contact force at 45 degrees of ER was 83.5 g. External rotation significantly increases the labrum-glenoid contact force and may influence the healing of a Bankart lesion.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.EJVS.2011.11.002
Abstract: The aim of this study was to create an ovine arteriovenous fistula (AVF) model which would closely replicate a human forearm fistula and use this to quantify the degree of intimal hyperplasia in those created with the U-Clip compared to a conventional sutured anastomosis. Twenty AVFs were created in 10 Border Leicester-Merino sheep between the superficial femoral artery and vein of each hind limb. On one side the U-Clip and on the other a continuous polypropylene suture was used to perform the anastomosis. The animals were sacrificed at 2 (n = 3), 4 (n = 4), 6 (n = 3) weeks and histological slices were taken of each AVF in cross section to determine the intimal media area per unit length (IMA/L). Intimal hyperplasia (IH) was observed at all time points with one AVF found occluded with thrombus at the time of harvest. The IMA/L was significantly lower in the U-Clip groups by 24% at 2 weeks, 32% at 4 weeks and 23% at 6 weeks (Two-way ANOVA, p = 0.019, observed power = 0.825, time or side p ≥ 0.766, type p = 0.001 Paired t-test, p < 0.001 between matched anastomotic types). Time taken to perform the anastomosis was similar between the two anastomotic techniques (Polypropylene 14(8-18) vs. U-Clip 15.3(11-23) min p = 0.47). This ovine AVF model results in IH similar to that seen in a human AVF. The IH that occurs with the U-Clip is less than that of continuous polypropylene suture.
Publisher: Elsevier BV
Date: 08-1998
DOI: 10.1016/S1010-5182(98)80016-4
Abstract: Even though osteodistraction has been well established in the extremities, the parameters used in craniofacial distraction have been essentially borrowed from orthopaedic experience. Latency is widely practised but its relevance has not been fully investigated. The purpose of this study was to establish the role of latency in mandibular distraction osteogenesis. Twenty-two growing Wethers sheep were allocated to four experimental groups. Six animals were allocated to each of Groups A, B and C and underwent bilateral mandibular corticotomies and attachment of an external lengthening device. Latent periods of 0, 4 and 7 days respectively were observed prior to beginning distraction. The distraction protocol consisted of a rate of 0.5 mm twice daily for 20 days, followed by a consolidation phase of 20 days after which the sheep were killed. Histology, bone densitometry and 3-point mechanical testing were performed on the harvested mandibles. Group D formed the control group (n = 4). Histologically, the distracted bone exhibited bone formation primarily via intramembranous ossification with scattered islands of cartilage. The regenerated bone had mechanical properties significantly weaker than the undistracted control group (P < 0.05), but between the experimental groups no statistically significant differences were demonstrable either in mechanical strength or DEXA density. These data indicate that a change in latency does not alter the properties of the regenerated bone in mandibular distraction osteogenesis and indeed no latent interval may be necessary at all in craniofacial distraction. This has implications for the duration of device fixation in distraction procedures.
Publisher: Elsevier BV
Date: 09-2000
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.JSE.2008.01.138
Abstract: An alteration in the stress and strain environment following arthroplasty is believed to lead to bone remodeling, which can trigger implant loosening and subsequent failure. Bone remodeling, while well-studied in hip arthroplasty, has received less attention in total shoulder replacement. This study examines differences in strain states between intact glenoids and following replacement with an uncemented metal backed keeled component and a cemented all polyethylene pegged component with the same articular geometry, using the photoelastic method. Strain measurements were taken in glenoids before and after implantation under 4 loading conditions corresponding to 4 abduction angles: 0 degrees, 30 degrees, 60 degrees, and 90 degrees. Shear strains increased at most locations following reconstruction with both of the implants. Uncemented, keeled metal backed implants produced areas of higher cortical shear strains compared to cemented, all PE pegged implants.
Publisher: Elsevier BV
Date: 1994
DOI: 10.1016/0142-9612(94)90263-1
Abstract: Bone tissue is an anisotropic non-homogeneous composite material composed of inorganic, bone mineral fibres (hydroxyapatite) embedded in an organic matrix (type I collagen and non-collagenous proteins). Factors contributing to the overall mechanical behaviour include constituent volume fraction, mechanical properties, orientation and interfacial bonding interactions. Interfacial bonding between the mineral and organic constituents is based, in part, on electrostatic interactions between negatively charged organic domains and the positively charged mineral surface. Phosphate and fluoride ions have been demonstrated to alter mineral-organic interactions, thereby influencing the mechanical properties of bone in tension. The present study explores the effects of phosphate and fluoride ions on the compressive properties of cortical bone.
Publisher: Wiley
Date: 07-08-2011
DOI: 10.1111/J.1525-1594.2011.01275.X
Abstract: A carbon fiber-reinforced polymer (CFRP) is theoretically a suitable material for use in an uncemented hip prosthesis considering it can provide isoelastic environment with the surrounding bone, adequate fatigue strength, and a metal-free radiographic evaluation. To date, the selection of polymer material and optimization of both design and surface finish of the prostheses for osseointegration has not been accomplished. This study examined radiographic and histologic results of an uncemented CFRP stem manufactured from carbon fiber-reinforced polyetheretherketone (CFR/PEEK) with a roughened surface and a bioactive treatment in an adult ovine model following a 12-month implantation period. A unilateral hemiarthroplasty of the hip was performed using the CFRP stem or a titanium stem as a control. Four cases with the CFRP stem and five cases with titanium stem were evaluated. Bone on-growth fixation was achieved in two cases with the CFRP stem and in all the cases with the titanium stem. The CFRP cases showed minimal stress shielding while three of five cases with the titanium stem demonstrated typical osteopenia associated with stiff metal stems. Bone on-growth to the uncemented CFRP stem was achieved by using the CFR/PEEK for the material and modifying the surface design and the bioactive surface finish. Bone resorption and osteopenia observed with the Ti stems was not found with the CFRP design.
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.ARTH.2005.03.039
Abstract: The pumping of fluid and polyethylene wear debris from the joint space to the retroacetabular bone is implicated in the pathogenesis of osteolysis. Three possible mechanisms for this pumping: pressure gradients, diaphragm pumping, and piston pumping were studied in vitro in a laboratory model. The simulated activities of rising from a chair and climbing stairs produced high-pressure gradients and high angles of loading that could pump fluid through the apical hole to the retroacetabular bone. A noncongruent liner acted as a diaphragm pump, producing pressures 6 times higher than that seen with a congruent liner. Pistoning motion of the liner produced pressures 8 times higher than when no pistoning occurs. These pumping mechanisms could be mitigated by the use of acetabular components without holes.
Publisher: Elsevier BV
Date: 10-2001
DOI: 10.1016/S0021-9290(01)00099-9
Abstract: Understanding the resistance forces encountered by a suture needle during tissue penetration is important for the development of robotic surgical devices and virtual reality surgical simulators. Tensile forces applied to skin and tendon during suturing were measured. Fresh sheep achilles tendons were tensioned with a static load 4.9 N, 9.8 N or 19.6 N and sheepskin with 0.98 N, 2.9 N or 4.9 N static load. A straight 2/0 cutting suture needle in series with a load cell on a materials testing machine penetrated the tissue at 90 degrees with a velocity of 1, 5 or 10mm/s for each tissue tension (n=5). Continuous load versus displacement data was obtained and penetration load and stiffness were noted. The load versus displacement curve for skin during needle penetration demonstrated two characteristic peaks, corresponding to initial penetration and emergence of needle from the undersurface of the tissue. Increasing the tension within the tissue (skin and tendon) increased the amount of force required to penetrate the tissue with a suture needle (p<0.05). Needle displacement rate did not affect the resistance to needle penetration (p<0.05). This study provides a simple model for measuring force-feedback during needle penetration of soft tissues and is a good starting point for future studies of the penetration resistance properties of human tissues.
Publisher: Elsevier BV
Date: 04-2006
DOI: 10.1016/J.ARTH.2005.03.032
Abstract: We have prospectively recorded ambient operating theater temperature from 186 total knee arthroplasties and the time taken for the cement to set at implantation. The majority of cases used Antibiotic Simplex cement (n = 131), and the rest, Simplex with tobramycin (n = 55). Set time was defined as when a no. 15 scalpel could not indent the cement surface at either the femoral or tibial interface. There was a reasonable negative correlation between temperature and setting time (Antibiotic Simplex: Pearson correlation coefficient, R = -0.674 Simplex with tobramycin: R = -0.655). There was also a considerable variation of setting time at any given theater temperature. There is an inverse relationship between ambient theater temperature and the setting time for Simplex cement, and surgeons should be aware that the setting time can vary considerably. Their operative protocol should take this into account.
Publisher: Wiley
Date: 15-10-2015
DOI: 10.1002/JOR.22741
Abstract: Modular hip implants allows for the adjustment of leg length, offset, and the ability to remove the head for acetabular exposure during primary and revision surgery. The design of the Morse taper facilitates the intimate contact of the conical trunnion of the femoral stem (male component), with the conical bore of the femoral head (female component). Orthopaedic trunnion tapers are not standardized and vary in length, taper angle, and base dimension. Variations in the design and surface characteristics of the trunnion, will directly reflect on the interface at the taper junction and can influence the likelihood of subsequent wear, corrosion and longevity of the implant. The effect of surface topography of trunnions on commercially available hip stems has not yet been considered as a possible contributing factor in the corrosion observed at taper junctions. In this study we analyzed the surface topography and surface roughness of randomly selected commercially available femoral hip stem trunnions to obtain a greater insight into their surface characteristics.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.KNEE.2008.01.012
Abstract: Many studies have shown that computer navigation in total knee arthroplasty aids the surgeon to place the prosthesis in a more accurate overall alignment. Bony resection creates the flexion and extension gaps important in balancing the knee and implant selection in TKR. The computer plans the bone cuts but has variables that it cannot control: the surgeon, the saw blade thickness and oscillation, the accuracy of the jigs, movement of the pins, and the quality of initial mapping data inputted by the surgeon. The accuracy of computer navigated bone resections are validated on cadavers, but this is the first study to compare the predicted bone cuts to that physically resected during TKR. For 89 patients undergoing primary TKR, the bone cut from the distal femur and proximal tibia was measured using Vernier callipers and compared to the computer calculation of the same. Results show that computer measurement of the physical space left by the resected bone is accurate.
Publisher: SAGE Publications
Date: 22-02-2013
Abstract: With increased numbers of reports using barbed sutures for tendon repairs we felt the need to design a specific tendon repair method to draw the best utility from these materials. We split 30 sheep deep flexor tendons in two groups of 15 tendons. One group was repaired with a new four-strand barbed suture repair method without knot. The other group was repaired with a conventional four-strand cross-locked cruciate repair method (Adelaide repair) with knot. Dynamic testing (3–30 N for 250 cycles) and additional static pull to failure was performed to investigate gap formation and final failure forces. The barbed suture repair group showed higher resistance to gap formation throughout the test. Additionally final failure force was higher for the barbed suture group compared with the conventional repair group. When used appropriately, barbed suture materials could be beneficial to use in tendon surgery, especially with regard to early loading of the repair site and gap formation.
Publisher: SAGE Publications
Date: 10-03-2011
Abstract: The use of PMMA cement is common in arthroplasty for cemented fixation and defect filling. Concerns remain regarding effects of cement curing temperature on the viability of cancellous bone. In this study we filled surgically-created defects (mean volume 0.585±0.251mL) in the cancellous bone of the distal femur and proximal tibia of 6 sheep with PMMA and measured temperature changes in surrounding bone whilst the cement cured, using 3 thermocouples per defect. Animals were euthanised at 3 (n=3) and 12 (n=3) weeks postoperatively and the bone-cement interface assessed histologically. Despite mean maximum temperatures of 49.3±10.2°C (range: 40.9°C - 82.2°C) thermonecrosis was not a common histological feature at either timepoint. The exposure of bone to high cement temperatures in this study has not led to bone necrosis and/or tissue damage.
Publisher: Springer Science and Business Media LLC
Date: 24-02-2011
DOI: 10.1007/S00167-011-1436-X
Abstract: Evaluate the biomechanical behavior of four variants of the transosseous-equivalent/suture bridge (TOE/SB) repair. Four suture bridge (SB) constructs were created using 24 sheep infraspinatus tendon-humerus constructs (n = 6 per technique). The groups were (1) Knotted Standard Suture Bridge (Standard SB)--suture bridge with two medial mattress stitches, (2) Knotted Double Suture Bridge (Double SB)--four medial mattress stitches, (3) Untied Suture Bridge with Medial FT Anchors (Untied SB with FT)--two medial mattress stitches without knots, and (4) Untied Suture Bridge with PushLocks (Untied SB with Pushlocks)--two medial mattress stitches without knots. The contact area footprint was measured with an electronic pressure film prior to dynamic mechanical testing for gapping and testing to failure. The Double SB produced the greatest contact area footprint compared to the other techniques, which did not differ. The Double SB repair with a mean failure load of 456.9N was significantly stronger than the Untied SB with Pushlocks repair at 300N (P = 0.023), the standard SB repair at 295N (P = 0.019), and lastly the Untied SB with FT repair at 284N (P = 0.011). No differences were detected between the two mattress stitch standard SB repair with knots and the knotless two mattress stitch repairs (Untied SB with FT and Untied SB with Pushlocks). Gaps developed during cyclic loading in all repairs apart from the Double SB repair. The transosseous-equivalent/suture bridge repair with 4 stitches tied in the medial row and maximal lateral suture strand utilization (Double SB) outperformed all other repairs in terms of failure load, tendon-bone contact, and gapping characteristics. The presence of knots in the medial row did not change tendon fixation with respect to failure load, contact area or gapping characteristics.
Publisher: Elsevier
Date: 2012
Publisher: Elsevier BV
Date: 12-1998
DOI: 10.1016/S0883-5403(98)90200-5
Abstract: The production of polyethylene wear debris in total knee arthroplasty (TKA) is due to multiple factors. In particular, inadequate implant alignment and high bearing surface contact stresses are associated with polyethylene failure. Optimal implant placement and soft tissue balancing may contribute to reducing wear and the production of polyethylene particles. We present a case in which a quantitative technique was used to measure tibiofemoral contact stresses during implantation of a total knee prosthesis in vivo. In a knee with preoperative varus and fixed flexion deformity, medial compartment contact stresses after initial resection were reduced from 14.3 MPa to 11.3 MPa in neutral alignment by additional bone resection. Posterior cruciate release was required to reduce contact stresses further and to provide satisfactory balance between medial and lateral compartments, as determined by the operating surgeon, and was confirmed by the measurement system (3.8 MPa medially 3.0 MPa laterally). This technique has potential to fine-tune implant positioning and ligament balancing during TKA.
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.AUCC.2010.06.004
Abstract: To determine the relationship between paracetamol administration and skin blood flow (skBF) and blood pressure (BP) in critically ill patients treated for fever. Prospective, observational study. Intensive care units of university teaching hospital. 29 adults (17 males and 12 females), aged 58±15 years treated with enteral or intravenous paracetamol for fever. APACHE II score was 17.2±8.3 and admission classifications were 41% medical (n=12), 31% surgical (n=9), and 28% neurological intervention (n=8). Thirty healthy afebrile volunteers were also studied after ingesting 1g paracetamol. Temperature, BP and skBF (laser Doppler flowmetry perfusion units) were recorded 15 min prior to administration of paracetamol, at administration (T0) and then for every 15 min for 60 min. Cutaneous vascular conductance (CVC=skBF/mean arterial pressure) was calculated. Thirty data sets were recorded from 29 patients. Temperature at T0 was 38.7±0.6°C. BP decreased over the study period whilst skBF and CVC increased (repeated measured ANOVA, p<.05). Systolic BP decreased significantly (p<.01) at all post-administration times and was 90±13% of T0 at 60 min. CVC was 128±48% of T0 at 60 min. Systolic BP fell by a clinically significant amount (≥15%) in 17 patients (59%) and hypotension was treated during 33% (n=10) of the observation periods. BP and skBF did not change significantly in afebrile volunteers. Paracetamol induced increases in skBF consistent with its antipyretic action and may be associated with significant falls in BP in the critically ill.
Publisher: MDPI AG
Date: 04-11-2022
Abstract: This study determined the intra- and inter-rater reliability of various shoulder testing methods to measure flexion range of motion (ROM), hand-behind-back (HBB), and external rotation (ER) strength. Twenty-four healthy adults (mean age of 31.2 and standard deviation (SD) of 10.9 years) without shoulder or neck pathology were assessed by two examiners using standardised testing protocols to measure shoulder flexion with still photography, HBB with tape measure, and isometric ER strength in two abduction positions with a hand-held dynamometer (HHD) and novel stabilisation device. Intraclass correlation coefficient (ICC) established relative reliability. Standard error of measurement (SEM) and minimum detectable change (MDC) established absolute reliability. Differences between raters were visualised with Bland–Altman plots. A paired t-test assessed for differences between dominant and non-dominant sides. Still photography demonstrated good intra- and inter-rater reliability (ICCs 0.75–0.86). HBB with tape measure demonstrated excellent inter- and intra-rater reliability (ICCs 0.94–0.98). Isometric ER strength with HHD and a stabilisation device demonstrated excellent intra-rater and inter-rater reliability in 30° and 45° abduction (ICCs 0.96–0.98). HBB and isometric ER at 45° abduction differed significantly between dominant and non-dominant sides. Standardised shoulder ROM and strength tests provide good to excellent reliability. HBB with tape measure and isometric strength testing with HHD stabilisation are clinically acceptable.
Publisher: SAGE Publications
Date: 2004
Abstract: This study reports the long-term histologic and mechanical properties of the healing patellar tendon–bone interface reconstructed using a high-density type I collagen bone anchor (HDC) compared to a metal anchor in sheep. To determine the long-term histology and mechanical properties of extra-articular tendon-bone healing and in vivo response to a HDC anchor. Controlled laboratory study. The structural properties, tendon-bone histology, and device histology in the bone were examined out to 208 weeks in a sheep model. The patellar tendon–proximal tibia bone interface continued to remodel with time but, by 4 years, had yet to develop the well-defined zones of tendon, fibrocartilage, calcified cartilage, and bone of the native patellar tendon to bone insertion. The insertion repair strength did not vary between the repaired tendons and the nonoperated controls at any time. The healing tendon-bone interface undergoes a gradual remodeling process, which had yet to reconstitute back to the control interface by 208 weeks. The HDC device remained essentially intact at 208 weeks showing little signs of degradation. Tendon-bone healing is mechanically equivalent to the contralateral side by 26 weeks whereas histologic structure requires much longer to remodel back to the native insertion.
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.ARTHRO.2006.09.003
Abstract: This study reports the mechanical and histologic properties of intra-articular tendon-bone healing with the application of low-intensity pulsed ultrasound (LIPUS) in an ovine knee model. A single digital extensor tendon autograft from the right hoof was used as the graft in 89 adult sheep. Femoral fixation was achieved with an EndoButton (Smith & Nephew Endoscopy, Andover, MA) and tibial fixation by tying over a bony post. LIPUS treatment was performed daily for 20 minutes over the femoral and tibial tunnels until sacrifice in all groups, apart from the 26-week group, which was treated only for the first 12 weeks. Histology was performed at 3, 6, 12, and 26 weeks. Mechanical testing was performed at 6, 12, and 26 weeks. The LIPUS-treated group showed increased cellular activity at the tendon-bone interface and general improvement in tendon-bone integration and vascularity. Stiffness and peak load were greater compared with the control group at 26 weeks after surgery (P < .05). The application of LIPUS appears to improve healing at the tendon-bone interface for soft tissue grafts fixed with a suspensory fixation technique. Histology supports a benefit based on increased integration between tendon and bone and a biologically more active interface, which would account for the improved mechanical properties. The indications of LIPUS may be expanded to include tendon-bone healing, for ex le, in anterior cruciate ligament reconstruction.
Publisher: Elsevier BV
Date: 07-2004
Publisher: Elsevier BV
Date: 09-1999
Abstract: Interest in craniofacial osteodistraction has increased in recent years parallel with the growing attention given to the role of growth factors in tissue healing and regeneration. This study was embarked upon to investigate the expression of bFGF, TGF-beta and IGF-1 in the distraction zone of the mandible. Fourteen growing sheep were allocated to three experimental groups. Six animals were allocated to Groups A and B (n = 12) and underwent bilateral mandibular corticotomies with fixation of an external lengthening device. The distraction protocol consisted of a rate of 1.0 mm/day (twice daily) for 20 days followed by a consolidation phase of 20 days after which the sheep were sacrificed. Group C comprised of age matched sham operated animals (n = 2). Bone histochemistry for growth factors were performed in the harvested mandibles. A strong staining of bFGF was seen in the osteoblasts, osteocytes and osteoid matrix following 20 days of distraction and 20 days of consolidation compared to the control group. TGF-beta and IGF-1 demonstrated mild but clear staining in osteocyte and osteoblast cells and TGF-beta stained positively in the osteoid seam in the experimental groups. These finding suggest that bFGF, IGF-1 and TGF-beta may play different roles in the remodelling phase of distraction osteogenesis.
Publisher: Public Library of Science (PLoS)
Date: 03-01-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2013
Publisher: Wiley
Date: 24-11-2003
DOI: 10.1046/J.1445-2197.2003.T01-13-.X
Abstract: Fracture healing is a cascade of events regulated by systemic and local factors. Local growth factors are believed to play an integral role. The present study evaluates the effects of basic fibroblast growth factor (bFGF) and insulin-like growth factor-1 (IGF-1) using a controlled delivery system in a closed rodent femoral fracture model. Female Wistar rats (n = 144) were used in the present study. Animals were randomly allocated to six groups, with each group ided into three time-points of 2, 4 and 8 weeks. Two groups had growth factor administered. The others had no operation or sham operations. Growth factors were delivered to the fracture site using a specialised delivery system. This consisted of a Kirschner-wire coated with ethylene vinyl acetate co-polymer embedded with growth factors, inserted as an intramedullary nail. Fractures were effected with a three-point bending device. Femurs were tested in four-point bending and structural properties of peak load and stiffness were obtained from the load-displacement graphs. Specimens were prepared for qualitative analysis under a light microscope and using immunohistochemistry, specimens were analysed for expression of bFGF, IGF-1 and transforming growth factor beta (TGF-beta). The growth factor-treated groups exhibited larger calluses at 2 and 4 weeks. Four-point bending showed weaker structural properties (stiffness and peak load) at 4 weeks in both growth factor-treated groups. Administration of bFGF or IGF-1 increased the ratio of cartilaginous to mesenchymal tissues in the fracture callus compared with non-treated animals at 2 and 4 weeks. Immunostaining intensity and distribution of both growth factors in the treated groups was greater than the non-treated groups. Exogenous delivery of bFGF or IGF-1 alters the course of fracture healing.
Publisher: MDPI AG
Date: 11-02-2022
DOI: 10.3390/MA15041346
Abstract: A biphasic calcium phosphate with submicron needle-shaped surface topography combined with a novel polyethylene glycol olylactic acid triblock copolymer binder (BCP-EP) was investigated in this study. This study aims to evaluate the composition, degradation mechanism and bioactivity of BCP-EP in vitro, and its in vivo performance as an autograft bone graft (ABG) extender in a rabbit Posterolateral Fusion (PLF) model. The characterization of BCP-EP and its in vitro degradation products showed that the binder hydrolyses rapidly into lactic acid, lactide oligomers and unaltered PEG (polyethylene glycol) without altering the BCP granules and their characteristic submicron needle-shaped surface topography. The bioactivity of BCP-EP after immersion in SBF revealed a progressive surface mineralization. In vivo, BCP-EP was assessed in a rabbit PLF model by radiography, manual palpation, histology and histomorphometry up to 12 weeks post-implantation. Twenty skeletally mature New Zealand (NZ) White Rabbits underwent single-level intertransverse process PLF surgery at L4/5 using (1) autologous bone graft (ABG) alone or (2) by mixing in a 1:1 ratio with BCP-EP (BCP-EP/ABG). After 3 days of implantation, histology showed the BCP granules were in direct contact with tissues and cells. After 12 weeks, material resorption and mature bone formation were observed, which resulted in solid fusion between the two transverse processes, following all assessment methods. BCP-EP/ABG showed comparable fusion rates with ABG at 12 weeks, and no graft migration or adverse reaction were noted at the implantation site nor in distant organs.
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.JHSA.2010.11.029
Abstract: The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation. We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined. All repairs failed by suture breakage we noted no suture pullout. There was no difference in load to failure (71.7-71.1 N p = .89) or stiffness (4.1-4.6 N/mm p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55-62.2 N p = .07). Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.
Publisher: Elsevier BV
Date: 1994
DOI: 10.1016/0267-6605(94)90118-X
Abstract: Recently, expanded polytetrafluoroethylene (ePTFE, Gortex) vascular grafts have been rolled and used for interpositional arthroplasties of the carpus in the wrist. Little data, however, are available on the response of human osteoblasts to ePTFE. In-vitro cell culture is a useful method to determine initial cell-biomaterial interactions. The present study explores the morphological and mitogenic response of human bone cells cultured on vascular grade ePTFE grafts. The present findings suggest that neither the inner nor the outer surface of ePTFE, in its present form, support osteoblast growth. PTFE may be a suitable material to act as a space filler for carpal bone interpositional arthroplasties.
Publisher: SAGE Publications
Date: 02-2001
Abstract: Fourteen pairs of explanted low contact stress (LCS) tibial interface components: six rotating platform (RP), six meniscal (MN) and two anterior-posterior (AP) glide designs, have been analysed with particular attention paid to the condition of the tibial counterfaces. The average surface roughness, R a , for the tibial trays ranged from 0.01 to 0.087 μm, significantly greater than the unworn control measurement of 0.008 μm. The scratch geometry analysis showed that the scratch peaks were found to be consistently of a lower aspect ratio than the scratch valleys and under 1 μm in height (average asperity height - R p = 0.52 μm, aspect ratio Δ p = 0.01, average asperity depth R v = 1.10 μm, Δ v = 0.05). The largest scratches were 3-4 μm in both R p and R v In vitro tests have shown that ultra-high molecular weight polyethylene (UHMWPE) wear increases in the presence of counterface scratches perpendicular to the direction of motion. In these explants, the unidirectional motion produced scratches parallel to the direction of sliding which is predicted to produce a smaller increase in UHMWPE wear. Other designs in mobile bearing knees have less constrained motion at the tibial counterface and this has been shown to accelerate wear it may also lead to a further increase in wear in the presence of third body scratches. It may be possible in future knee designs to reduce this type of wear damage by introducing alternative materials or coatings which are more resistant to scratching and surface roughening.
Publisher: Wiley
Date: 07-2002
DOI: 10.1046/J.1445-2197.2002.02424.X
Abstract: There are many clinical situations in which immune suppression or deficiency occurs. This may lead to healing impairment. The aim of the present study was to characterize the effect of T lymphocyte deficiency on wound healing, and on -platelet-derived growth factor (PDGF), bFGF (basic fibroblast growth factor) and insulin-like growth factor-1 (IGF-1) expression, using an animal model. Nude and normal 10-12-week-old male BALB/c mice were given standard dermal incisions and killed at 1, 2, 4 or 6 weeks postinjury. The pelts were harvested and the wounds cut (perpendicularly) into strips for analysis. Strips from each animal were tested mechanically or processed for histological assessment and immunohistochemical detection of PDGF, bFGF and IGF-1 and colour video image analysis. The data were assessed by analysis of variance (anova). The interaction between species and time resulted in statistically significant differences in mechanical properties. Wound peak load was higher in nude mice at weeks 1 and 2 postinjury, but lower in nude mice at week 6 postinjury. Colour video image analysis demonstrated that the expression of bFGF and IGF-1 was greater in nude mice at week 1 postinjury (P < 0.05). The mechanical data suggest that the overall effect of the T lymphocyte system on wound healing is initially inhibitory and later stimulatory. This may be associated with corresponding differences in wound growth factor expression.
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.JHSA.2007.05.017
Abstract: The vincula are specialized mesotendinous structures attaching to the flexor tendons of the hand. In addition to providing vascular supply to the tendons, the vincula can be mechanically important. The purpose of this study was to quantify the influence of intact vincula on digital flexion after flexor tendon laceration and to assess the ultimate strength and stiffness of the vincula. The index, middle, and ring fingers of 12 fresh-frozen cadaveric fingers were dissected free at the level of the metacarpophalangeal joint, preserving at least 10 cm of the flexor and extensor tendons. A 9.8-N load was applied to each flexor tendon, and using digital photography and image analysis software, the degree of flexion at the proximal and distal interphalangeal joints and excursion of tendons proximal to the metacarpophalangeal joint was recorded before and after ision of the flexor digitorum profundus and flexor digitorum superficialis tendons at their insertions. Load to failure and stiffness of the vincula were measured via a uniaxial material testing apparatus. Analysis of means was performed with a paired t-test. After ision of the flexor digitorum superficialis tendon, proximal interphalangeal joint flexion secondary to the influence of the intact vincula was 93% of that compared with the uninjured digit. Distal interphalangeal joint flexion after flexor digitorum profundus transection was 69% of normal. The increased excursion of transected tendons compared with testing before ision was 4 mm for flexor digitorum superficialis and 2 mm for flexor digitorum profundus. Load to failure was 27 N, and stiffness was 6 N/mm. The vincula breve can facilitate digital flexion after distal tendon transection, allowing tendons to act indirectly across the interphalangeal joints. The intact vincula breve can facilitate an almost normal range of motion across the interphalangeal joints, making the diagnosis of a flexor tendon injury difficult. In the immediate postinjury period, the vincula breve can hold a ided tendon within a few millimeters of its insertion. Testing against resistance is important to avoid missing the diagnosis of a tendon injury.
Publisher: Springer Science and Business Media LLC
Date: 16-04-2014
DOI: 10.1007/S10561-014-9447-8
Abstract: Bone allografts are used to replace bone that has been removed or to augment bone tissue in a number of clinical scenarios. In order to minimize the risk of infection and immune response, the bone is delipidated and terminally sterilized prior to implantation. The optimal method for bone graft sterilization has been the topic of considerable research and debate. Recently, supercritical carbon dioxide (SCCO(2)) treatments have been shown to terminally sterilize bone against a range of bacteria and viruses. This study aimed to evaluate the effect of these SCCO(2) treatments on the anisotropic mechanical properties of cortical bone. Adult bovine cortical cubes were prepared and treated using SCCO(2) and a range of common processing additives (ethanol, peracetic acid and hydrogen peroxide). The bone was mechanically tested in uniaxial compression in the axial, radial and tangential orientations. Ultimate stress, strain, elastic modulus, energy and stiffness were evaluated. This study found that SCCO(2) treatment without additive did not alter the ultimate stress, stiffness or energy to failure depreciably in any orientation. The addition of sterilants peracetic acid and hydrogen peroxide also preserved mechanical function, with no deleterious effect on stress or stiffness. This study highlights the expediency of SCCO(2) treatment for bone allograft processing as terminal sterilization can be achieved while maintaining the intrinsic mechanical properties of the graft.
Publisher: MDPI AG
Date: 09-03-2022
DOI: 10.3390/IJMS23062952
Abstract: The prevention and treatment of biofilm-mediated infections remains an unmet clinical need for medical devices. With the increasing prevalence of antibiotic-resistant infections, it is important that novel approaches are developed to prevent biofilms forming on implantable medical devices. This study presents a versatile and simple polydopamine surface coating technique for medical devices, using a new class of antibiotics—antimicrobial peptidomimetics. Their unique mechanism of action primes them for activity against antibiotic-resistant bacteria and makes them suitable for covalent attachment to medical devices. This study assesses the anti-biofilm activity of peptidomimetics, characterises the surface chemistry of peptidomimetic coatings, quantifies the antibacterial activity of coated surfaces and assesses the biocompatibility of these coated materials. X-ray photoelectron spectroscopy and water contact angle measurements were used to confirm the chemical modification of coated surfaces. The antibacterial activity of surfaces was quantified for S. aureus, E. coli and P. aeruginosa, with all peptidomimetic coatings showing the complete eradication of S. aureus on surfaces and variable activity for Gram-negative bacteria. Scanning electron microscopy confirmed the membrane disruption mechanism of peptidomimetic coatings against E. coli. Furthermore, peptidomimetic surfaces did not lyse red blood cells, which suggests these surfaces may be biocompatible with biological fluids such as blood. Overall, this study provides a simple and effective antibacterial coating strategy that can be applied to biomaterials to reduce biofilm-mediated infections.
Publisher: Elsevier BV
Date: 12-1995
DOI: 10.1016/0142-9612(95)96871-V
Abstract: Mineralizing biological tissues are complex bioceramic-biopolymer composites engineered for a variety of functions. The organic and inorganic constituents, morphology, location, orientation, crystallinity and interactions exhibit materials or extremely fine microstructure, unique mechanical and physical properties with high strength and fracture toughness compared to the in idual constituents. An understanding of mineralization, ultrastructural organization and interfacial bonding forces in mineralizing biological composite tissues, such as bone, may provide new strategies and techniques for the production of a novel class of man-made organic-ceramic composites. The present study explores the use of the organic matrix remaining after removal of the mineral phase by chelation with EDTA or solubilizing in HCl as a template for mineral deposition and the production of mineral-organic composites. Different pH conditions are employed to alter the inorganic phase which is deposited within the organic matrix. Mechanical testing and ultrastructural evaluations are carried out for characterization.
Publisher: Elsevier BV
Date: 09-2002
Abstract: Proximal and distal articulations surface roughness measurements were done on 8 mobile bearing knee designs immediately after removal from sterile packaging. Roughness parameters Ra and Rp based on ISO 97, representing mean deviation from the smooth surface line and mean peak to smooth surface line, were recorded using a contact surface profilometer at 10 random sites in the anteroposterior and mediolateral direction on the femoral and tibial metal components and the proximal and distal surface of the ultra-high molecular weight polyethylene (PE) inserts. No differences were found for surface roughness values for the metal components. Surface roughness values were greater for the distal PE bearing surfaces compared with the proximal PE bearing surfaces for each design tested. The roughness values for the PE inserts showed a directional dependence. Complex kinematics of mobile bearing knees coupled with this rougher distal interface could influence the rate of generation of wear particles and total volume of particles produced especially in the early postoperative period.
Publisher: IEEE
Date: 12-2008
Publisher: Wiley
Date: 07-07-2009
DOI: 10.1002/PROS.21010
Abstract: Bone metastasis is a frequent and catastrophic consequence of prostate cancer for which only palliative treatment is available. Animal models of bone metastatic prostate cancer are necessary for understanding disease mechanisms but few models exist. We have used the murine prostate carcinoma cell line RM1 to generate a bone metastatic model of prostate cancer. Repeated intracardiac injection of RM1 cells followed by isolation of cells from bone tumors has yielded a cell line with strong bone-metastatic potential, RM1 bone metastatic (BM). This cell line metastasizes to multiple bony sites in over 95% of injected C57BL/6 mice and is far less tropic to soft tissues. Bone tumors produced by the RM1(BM) cell line show no preference for particular skeletal sites as most bones are affected. Histology, and micro-computed tomography show that RM1(BM) cells form osteolytic tumors, but with evidence of osteoblastic changes. In vitro the RM1 cells express E-cadherin but not vimentin, do not form colonies in soft agar, are non-invasive but are more motile than the parent cell line. This model provides a novel means for identifying cellular and molecular mechanisms that contribute to bone metastasis and allow for preclinical testing of therapies to prevent and treat tumor metastasis to bone. Finally as the syngeneic tumor cells are injected into immunocompetent mice, this model will provide a means to study interactions between the immune system, tumors and bone, and therapies that target such interactions.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2011
DOI: 10.2106/JBJS.J.00711
Publisher: Elsevier BV
Date: 05-2001
Abstract: The pullout strength of a collagen bone anchor that creates interference fixation as the result of radial swelling on hydration was compared with a Mitek rotator cuff anchor after insertion into the greater tuberosity of human cadaver humeri. Bones were fully hydrated at 37 degrees C. Stiffness, peak load, and the mode of failure were recorded. Real and apparent bone densities were measured. Peak load for the collagen anchor at 15 minutes (121.0N +/- 81.3N) was greater than at 2 minutes (60.5N +/- 38.5N) after insertion (P <.05). At between 5 and 60 minutes after insertion, peak loads for the Mitek and the collagen anchors did not differ. After 30 minutes from insertion, the mode of failure of the collagen anchor changed from pullout with minor body damage to pullout with major body damage. Peak load at pullout correlated with bone density for the Mitek (P <.05, r = 0.516) but for the collagen bone anchor appeared unaffected by bone density.
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.ARTH.2008.08.015
Abstract: Metal-on-metal articulations are increasingly used in total hip arthroplasty. Patients can be sensitive to metal ions produced by the articulation and present with pain or early loosening. Infection must be excluded. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. There is no practical guide in the literature on how to differentiate between allergy and infection in a painful total hip arthroplasty. We present the history, clinical findings and hip scores, radiology, serology, hip arthroscopy and aspirate results, labeled white cell scan, revision-hip findings, histology and clinical results of a typical patient with a hypersensitivity response to a metal-on-metal hip articulation, and how results differ from patients with an infected implant. A practical scheme to investigate patients with a possible hypersensitivity response to an implant is presented.
Publisher: Wiley
Date: 07-2002
DOI: 10.1046/J.1445-2197.2002.02459.X
Abstract: Previous studies have demonstrated that high pressures are generated at the tips of laparoscopic graspers, which can cause tissue injury. This study examines the effect of a compliant edge on tip pressure. One of a pair of identical laparoscopic graspers was modified by refashioning the tip out of silicone. A thin film pressure transducer (I-scan 6900 sensor) was deployed between the jaws of the grasper and a simulated tissue (leather strap). Load and handle pressures were kept constant. Peak tip pressure readings were taken as the load orientation was increased from the perpendicular to 135 degrees (n = 10). The data was analysed using anova and a post-hoc Duncan's multiple range test. Peak tip pressures generated by the compliant tipped grasper were significantly less than those developed by the unmodified grasper, particularly at high-load orientations. High pressures generated at the tip of laparoscopic graspers can be reduced by altering the mechanical properties (compliance) of the tip.
Publisher: MDPI AG
Date: 17-12-2020
DOI: 10.3390/S20247238
Abstract: Background: Objective assessment of shoulder joint active range of motion (AROM) is critical to monitor patient progress after conservative or surgical intervention. Advancements in miniature devices have led researchers to validate inertial sensors to capture human movement. This study investigated the construct validity as well as intra- and inter-rater reliability of active shoulder mobility measurements using a coupled system of inertial sensors and the Microsoft Kinect (HumanTrak). Methods: 50 healthy participants with no history of shoulder pathology were tested bilaterally for fixed and free ROM: (1) shoulder flexion, and (2) abduction using HumanTrak and goniometry. The repeat testing of the standardised protocol was completed after seven days by two physiotherapists. Results: All HumanTrak shoulder movements demonstrated adequate reliability (intra-class correlation (ICC) ≥ 0.70). HumanTrak demonstrated higher intra-rater reliability (ICCs: 0.93 and 0.85) than goniometry (ICCs: 0.75 and 0.53) for measuring free shoulder flexion and abduction AROM, respectively. Similarly, HumanTrak demonstrated higher intra-rater reliability (ICCs: 0.81 and 0.94) than goniometry (ICCs: 0.70 and 0.93) for fixed flexion and abduction AROM, respectively. Construct validity between HumanTrak and goniometry was adequate except for free abduction. The differences between raters were predominately acceptable and below ±10°. Conclusions: These results indicated that the HumanTrak system is an objective, valid and reliable way to assess and track shoulder ROM.
Publisher: MDPI AG
Date: 06-10-2023
Publisher: Springer Science and Business Media LLC
Date: 28-05-2009
Publisher: Elsevier BV
Date: 08-2005
DOI: 10.1016/J.CLINBIOMECH.2005.03.012
Abstract: This study used in vitro cyclic testing protocol to examine the dynamic properties from a survivorship point of view for a modified Kessler core suture with a running epitenon suture, a modified Kessler core suture with a cross-stitched epitenon suture and a 4-strand Savage core suture with a running epitenon suture. A survivorship analysis using in vitro dynamic mechanical testing was performed using 20 N and 33 N with 500 cycles to simulate early rehabilitation. The gap formation was recorded by direct measurement with an electronic calliper every 100 cycles at the point of lowest force during the cycle at the site of greatest gap formation. Results were analysed using a log rank test for survival analysis and the relative risk of deterioration calculated. No significant increased risk of gap formation was noted for the Kessler with a cross-stitched epitenon over the standard Kessler repair. A significant decrease in the risk of significant gap formation in the Savage repair over the two Kessler repairs (>10-fold difference in the standard (P 7-fold in the cross-stitched (P < 0.05) was found. The survivorship testing protocol found the Savage repair to be superior to the other methods under dynamic loading. Survival curves and relative risks provide a unique way to assess the properties of different repair techniques.
Publisher: Cold Spring Harbor Laboratory
Date: 05-06-2020
DOI: 10.1101/2020.06.04.130872
Abstract: Terminally differentiated murine osteocytes and adipocytes can be reprogrammed using platelet-derived growth factor–AB and 5-Azacytidine into multipotent stem cells with stromal cell characteristics. To generate a product that is amenable for therapeutic application, we have modified and optimised culture conditions to reprogram human adipocytes into induced multipotent stem cells (iMS) and expand them in vitro . The basal transcriptomes of adipocyte-derived iMS cells and matched adipose-tissue-derived mesenchymal stem cells were remarkably similar. However, there were distinct changes in histone modifications and CpG methylation at cis- regulatory regions consistent with an epigenetic landscape that was primed for tissue development and differentiation. In a non-specific tissue injury xenograft model, iMS cells contributed directly to new muscle, bone, cartilage and blood vessels with no evidence of teratogenic potential. In a cardiotoxin muscle injury model, iMS cells contributed specifically to satellite cells and myofibres without ectopic tissue formation. Taken together, human adipocyte derived iMS cells regenerate tissues in a context dependent manner without ectopic or neoplastic growth.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.SPINEE.2014.12.018
Abstract: Rapid and stable fixation at the bone-implant interface would be regarded as one of the primary goals to achieve clinical efficacy, regardless of the surgical site. Although mechanical and physical properties of polyetheretherketone (PEEK) provide advantages for implant devices, the hydrophobic nature and the lack of direct bone contact remains a limitation. To examine the effects of a plasma-sprayed titanium coated PEEK on the mechanical and histologic properties at the bone-implant interface. A preclinical laboratory study. Polyetheretherketone and plasma-sprayed titanium coated PEEK implants (Ti-bond Spinal Elements, Carlsbad, CA, USA) were placed in a line-to-line manner in cortical bone and in a press-fit manner in cancellous bone of adult sheep using an established ovine model. Shear strength was assessed in the cortical sites at 4 and 12 weeks, whereas histology was performed in cortical and cancellous sites at both time points. The titanium coating dramatically improved the shear strength at the bone-implant interface at 4 weeks and continued to improve with time compared with PEEK. Direct bone ongrowth in cancellous and cortical sites can be achieved using a plasma-sprayed titanium coating on PEEK. Direct bone to implant bonding can be achieved on PEEK in spite of its hydrophobic nature using a plasma-sprayed titanium coating. The plasma-sprayed titanium coating improved mechanical properties in the cortical sites and the histology in cortical and cancellous sites.
Publisher: Springer Science and Business Media LLC
Date: 27-05-2013
DOI: 10.1007/S10561-012-9318-0
Abstract: Load bearing bone allografts are used to replace the mechanical function of bone that has been removed or to augment bone that has been damaged in trauma. In order to minimize the risk of infection and immune response, the bone is delipidated and terminally sterilized prior to implantation. The optimal method for bone graft sterilization has been the topic of considerable research. Recently, supercritical carbon dioxide (SCCO(2)) treatments have been shown to terminally sterilize bone against a range of bacteria and viruses. This study aimed to evaluate the effect of SCCO(2) treatment compared with two doses of gamma irradiation, on the mechanical properties of whole bone. Paired rabbit humeri were dissected and randomly assigned into either SCCO(2) control, SCCO(2) additive or gamma irradiation at 10 or 25 kGy treatment groups. The bones were mechanically tested in three-point and four-point bending and torsion, with the lefts acting as controls for the treated rights. Maximum load, energy to failure and stiffness were evaluated. This study found that SCCO(2) treatment with or without additive did not alter maximum load, energy to failure or stiffness significantly under any loading modality. Gamma irradiation had a deleterious dose dependant effect, with statistically significant decreases in all mechanical tests at 25 kGy while at 10 kGy there were reductions in all loading profiles, though only reaching statistical significance in torsion. This study highlights the expediency of SCCO(2) treatment for bone allograft processing as terminal sterilization can be achieved while maintaining the intrinsic mechanical properties of the graft.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2016
Publisher: Mary Ann Liebert Inc
Date: 10-2014
Publisher: Wiley
Date: 07-2003
Publisher: Springer Science and Business Media LLC
Date: 31-03-2013
DOI: 10.1007/S00167-012-1972-Z
Abstract: The purpose of this study was to examine the effects Low-intensity Pulsed Ultrasound has on initial tendon-bone healing in a clinically relevant extra-articular transosseous-equivalent ovine rotator cuff model. Eight skeletally mature wethers, randomly allocated to either control group (n = 4) or treatment group (n = 4), underwent rotator cuff surgery following injury to the infraspinatus tendon. All animals were killed 28 days post surgery to allow examination of early effects of Low-intensity Pulsed Ultrasound treatment. General improvement in histological appearance of tendon-bone integration was noted in the treatment group. Newly formed woven bone with increased osteoblast activity along the bone surface was evident. A continuum was observed between the tendon and bone in an interdigitated fashion with Sharpey's fibres noted in the treatment group. Low-intensity Pulsed Ultrasound treatment also increased bone mineral density at the tendon-bone interface (p < 0.01), while immunohistochemistry results revealed an increase in the protein expression patterns of VEGF (p = 0.038), RUNX2 (p = 0.02) and Smad4 (p = 0.05). The results of this study indicate that Low-intensity Pulsed Ultrasound may aid in the initial phase of tendon-bone healing process in patients who have undergone rotator cuff repair. This treatment may also be beneficial following other types of reconstructive surgeries involving the tendon-bone interface.
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.SPINEE.2014.01.043
Abstract: The ideal tissue-engineered solution for any bone graft substitute is to assist in the rapid formation of bone and facilitate fusion. The present study aims to evaluate this E-BMP-2 (Escherichia coli-derived human bone morphogenetic protein-2) in ovine posterolateral lumbar fusion (PLF) to examine the influence of dose and overall performance in a model with similar graft size and diffusive challenges to the human. In vivo large animal model study. An adult ovine PLF was performed in 30 animals with groups of E-BMP-2 with a beta-tricalcium phosphate (β-TCP) carrier at three different dosages, β-TCP alone, and autograft from the iliac crest. The fusions were assessed by radiography (X-ray and microcomputed tomography), mechanical testing, and hard-tissue histology with bone labels at 6, 8, and 10 weeks along with routine paraffin histology at 12 weeks. Results showed increasing new bone and fusion rate with E-BMP-2 dose, whereas β-TCP alone was largely resorbed and did not achieve fusion in this model at 12 weeks. Autograft showed similar grading for the amount of bone between the transverse processes but a lower fusion rate than β-TCP/E-BMP-2 groups. Bone labels revealed new bone formation at all time points for the E-BMP2 groups, whereas the autograft group showed active bone formation at 10 weeks. Beta-tricalcium phosphate displayed reliable incorporation into the decorticated host bone, whereas limited new bone was found between the transverse processes. At the center of the fusion mass, increased E-BMP-2 dose led to increased incorporation of β-TCP by new bone. These results suggest that E-BMP-2 was capable of producing posterolateral fusion in the ovine model that is equal to or superior to autologous graft in terms of fusion rate and mechanical strength. E-BMP-2 dose had considerable influence on β-TCP granule resorption.
Publisher: Wiley
Date: 09-01-2017
DOI: 10.1111/OS.12283
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.JHSA.2007.10.011
Abstract: The time-dependent mechanical behavior of common suture materials may have a pronounced influence on the quality of flexor tendon repairs with respect to gap formation. Sutures commonly used in plastic surgery, particularly for hand tendon repair, were tested in tension for analysis of stress relaxation and creep properties. The three materials tested were (1) Prolene, a monofilament polypropylene(Ethicon, Somerville, NJ) (2) Ethilon, a monofilament nylon(Ethicon, Somerville, NJ) and (3) Ticron, a braided polyester fiber (Sherwood, Davis & Geck, St. Louis, MO). All measurements were made with 1.5-mm (4-0) varieties of the sutures, in physiological buffered solution (0.9% phosphate-buffered saline [PBS]) at both room (22 degrees C) and body temperature (37 degrees C) conditions. Ticron was the stiffest suture at both room and body temperature, followed by Prolene and Ethilon. Both Prolene and Ethilon showed statistically (p< .05) reduced stiffness at body temperature. Prolene exhibited statistically larger (p< .05) relaxation and creep ratios than the other two sutures, and it was the only material to show temperature effects in creep and relaxation. Based on static and viscoelastic mechanical properties, Ticron is the most suitable suture for flexor tendon repairs when compared to Prolene and Ethilon.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-01-2021
Abstract: Human adipocytes are a source of tissue-regenerative multipotent stem cells.
Publisher: Springer Science and Business Media LLC
Date: 20-12-2013
DOI: 10.1007/S00590-011-0931-6
Abstract: During tendon autograft harvest, either a grasping suture or traditional whip stitch can be used to grasp tendon prior to definitive bone fixation. Their grip strength has not, to our knowledge, been compared. This article compares a needle-free suture technique to a standard whip stitch by testing grip strength in vitro. Twelve uniform ovine flexor tendons were prepared six tendons with a standard, non-locking whip stitch and six tendons with a grasping suture. All the s les were tested to failure in uniaxial tension in a materials testing machine. Load/displacement curves were generated, and qualitatively assessed and peak loads were compared. There were no significant differences between the groups in tendon length or diameter. Modes of failure between the groups, as characterised by the load/displacement curves, were quite distinct. Peak load to failure was lower in the utility suture group (mean peak load at failure 121.28 N) than the whip stitch group (mean peak load to failure 188.82 N). All failures in the utility suture group occurred when the suture snapped. The grasping suture described here is weaker than a standard whip stitch but may be sufficiently strong to harvest and handle tendon autograft. A standard whip stitch remains the choice for definitive graft fixation.
Publisher: Elsevier BV
Date: 09-2003
DOI: 10.1016/S0021-9290(03)00158-1
Abstract: A novel method for the measurement of knee joint forces in-vivo is described. A thin (0.2mm) flexible electronic pressure sensor was inserted through a narrow arthroscopic portal into the osteoarthritic medial compartment of the knee joint. The sensor partially covered the load bearing area. The surgery was performed under local anaesthetic during normal arthroscopic examination following patient consent. Results are presented for 11 patients. The method was used in a pilot study to assess the effects of four valgus knee braces on medial compartment forces. An analysis of variance could not detect un-loading by any brace although there were large variations in force output. These variations may be attributable to shifts in the sensor position. In-vivo measurement of joint force is technically feasible.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-04-2011
DOI: 10.2106/JBJS.I.01753
Publisher: Elsevier BV
Date: 09-2004
Publisher: Elsevier BV
Date: 09-2004
Publisher: Springer Science and Business Media LLC
Date: 07-1994
DOI: 10.1007/BF02368247
Publisher: SAGE Publications
Date: 05-12-2016
Publisher: Wiley
Date: 28-11-2018
DOI: 10.1002/JSP2.1039
Publisher: S. Karger AG
Date: 2016
DOI: 10.1159/000447329
Abstract: b i Background: /i /b Transbronchial lung biopsy using a cryoprobe is a novel way of s ling lung parenchyma. Correlation of freezing time with biopsy size and complications has not been evaluated in vivo. b i Objectives: /i /b The primary aim of the study is to evaluate the correlation between transbronchial cryobiopsy freezing time and size. The secondary aims are to evaluate histological quality of the biopsy and evaluate procedure-associated complications. b i Methods: /i /b Transbronchial lung cryobiopsies were obtained from two anaesthetised sheep using a 1.9-mm cryoprobe inserted into a flexible bronchoscope under fluoroscopic guidance. Freezing times ranged from 1 to 6 s (n = 49). The cryobiopsies were evaluated histologically with respect to their size and quality. Complications of bleeding and pneumothorax were recorded. b i Results: /i /b The mean cross-sectional area of the cryobiopsy ranged from 4.7 ± 2.1 to 15.7 ± 15.3 mm sup /sup . There was a significant positive correlation between increasing freezing time and cryobiopsy cross-sectional area (p = 0.028). All biopsies contained lung tissue with preserved parenchyma. Crush and freeze artefacts were not observed and tissue architecture was intact in all specimens. Small blood vessels and terminal bronchioles were observed in 88% of specimens. All cryobiopsies caused nil or mild haemorrhage with the exception of only 1 episode of severe haemorrhage at 6 s freezing time. Pneumothoraces occurred at 2, 5 and 6 s freezing time and required chest tube insertion. The most significant haemorrhage and pneumothoraces occurred at 5 and 6 s. Our results suggest an initial freezing time of 3 s can provide the maximal biopsy size while minimising major complications. b i Conclusion: /i /b The optimal transbronchial cryobiopsy freezing time is initially 3 s. This time is associated with minimal complications and large artefact-free biopsies.
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.JBIOMECH.2013.04.006
Abstract: The optimal sterilization method for load bearing allografts remains a clinical concern. Recently, supercritical carbon dioxide (SCCO2) treatments have been shown to be capable of terminally sterilizing a range of bacteria and viruses, while preserving the static mechanical properties of cortical bone. This study evaluated the effect of SCCO2 treatment compared with two doses of gamma irradiation, on clinically relevant dynamic mechanical properties of cortical bone. Quasi-static testing was also performed to compare the impairment of treatment. Whole paired adult rabbit humeri were dissected and randomly assigned into either SCCO2 Control, SCCO2 Additive or gamma irradiation at 10 or 25kGy treatment groups. The bones were treated and mechanically tested in three-point bending, with the lefts acting as controls for the treated rights. Maximum load, energy to failure and stiffness were evaluated from static tests. The number of cycles to failure was determined for fatigue at 6-60% of the ultimate load. This study found that SCCO2 treatment with or without additive did not alter static or dynamic mechanical properties. Gamma irradiation had a deleterious dose dependent effect, with statistically significant (p<0.05) reductions in all static mechanical parameters at 25kGy. This effect was increased in fatigue with statistically significant decreases in both the 10 and 25kGy dose groups. This study highlights the expediency of SCCO2 treatment for load bearing bone allograft processing as terminal sterilization can be achieved while maintaining both the quasi-static and dynamic mechanical properties of the graft.
Publisher: Wiley
Date: 07-2002
Abstract: To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of healing superficial digital flexor tendon (SDFT) in horses. Completely randomized design. Twelve Standardbred horses, 3 to 7 years of age, with ultrasonographically normal forelimb SDFT. One week after induction of collagenase (2,000 U) induced superficial flexor tendonitis, horses were randomly ided into groups of 6. One group was administered intramuscular rEGH (10 microg/kg/day for 1 week, then 20 microg/kg/day for 5 weeks), whereas the other group (control subjects) were administered an equivalent volume of saline (0.9% NaCl) solution. At the end of this 6-week treatment, horses were killed and one forelimb SDFT from each horse was harvested for biomechanical testing under uniaxial tension. Results were analyzed using an unpaired Student's t test significance was set at P <or=.05. SDFT from horses treated with rEGH had significantly larger mean cross-sectional areas and lower mean values for ultimate and yield tensile stress, whereas tendons from the control group were biomechanically stiffer than those from the rEGH-treated horses. Administration of rEGH to horses for 6 weeks, 1 week after collagenase induced injury to the SDFT, resulted in a significant increase in tendon cross-sectional area, a concomitant reduction in ultimate and yield tensile stress, and reduced tendon stiffness. Using this model of tendonitis, rEGH had a negative effect on the biomechanical properties of equine SDFT in the early phases of healing. Based on our results, administration of rEGH to treat superficial flexor tendonitis cannot be recommended.
Publisher: Wiley
Date: 07-2002
Abstract: To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of normal adult equine superficial digital flexor tendon (SDFT). Completely randomized design. Nine Standardbred horses, 6 to 9 years of age with ultrasonographically normal forelimb SDFT. Six horses were administered intramuscular (IM) rEGH at 10 microg/kg/day for 1 week, and then 20 microg/kg/day for another 5 weeks 3 horses (control subjects) were administered an equivalent daily volume of sterile water IM. Horses were killed at the end of the 6-week treatment period, and both forelimb SDFT were harvested and stored at -70 degrees C. In vitro biomechanical testing was performed under uniaxial tension. Results were analyzed using a general linear model of analysis of variance significance was set at P <.05. There were no differences in cross-sectional area, maximal load at failure, yield load, ultimate and yield tensile strain, ultimate and yield tensile stress, or stiffness between tendons from control and treated horses. Administration of rEGH to adult Standardbred horses for 6 weeks had no detectable effect on the in vitro biomechanical properties of normal SDFT. Administration of rEGH does not modulate the in vitro biomechanical properties of SDFT from adult Standardbred horses.
Publisher: Springer Science and Business Media LLC
Date: 15-01-2015
DOI: 10.1007/S10561-014-9492-3
Abstract: Sterilisation of allografts are a crucial step in ensuring safety and viability. Current sterilisation standards such as 25 kGy gamma irradiation (γ) can have adverse effects on the ultrastructure and biomechanical properties of allograft tissue. Supercritical CO2 (SCCO2) technology, represents an improved sterilisation process that potentially preserves tissue properties. This study aimed to test the effect of SCCO2 sterilisation on the biomechanical and histological properties of the meniscus and compare this to the current standard of γ. Thirty-two 18-month old ovine menisci were randomly assigned into three groups for sterilisation (SCCO2, γ and control). After treatment, biomechanical indentation testing (stiffness and stress relaxation) or histological analysis [percentage of void, cells and extracellular matrix (ECM) per slide] was undertaken. Both SCCO2 and gamma groups displayed an increase in stiffness and stress relaxation as compared to control, however, this difference was lesser in s les treated with SCCO2. No significant histological quantitative differences were detected between SCCO2 and control specimens. Gamma-treated s les demonstrated a significant increase in void and decrease in ECM. Interestingly, both treatment groups demonstrated a decreasing mean void and increasing ECM percentage when analysed from outer to inner zones. No significant differences were detected in all-endpoints when analysed by section. SCCO2 sterilisation represents a potential feasible alternative to existing sterilization techniques such as γ.
Publisher: Elsevier BV
Date: 08-1993
DOI: 10.1016/S0749-8063(05)80316-0
Abstract: A bovine model was developed for biomechanical evaluation of anterior cruciate ligament (ACL) reconstruction using patellar bone-tendon-bone (b-t-b) autograft to examine the differences in time zero fixation mechanical properties of different interference screw lengths and diameters. The surgical technique of interference screw fixation of the b-t-b complex performed clinically was reproduced in a controlled animal model. The femur-patellar tendon graft-tibia complex was tested with anterior displacement of the tibia in 30 degrees of knee flexion to allow examination of the femoral and tibial fixation properties simultaneously. The statistical model concurrently explored differences between screw length and diameter while accounting for variations between graft properties. No statistically significant differences were found between the 7- and 9-mm screws with respect to peak load or energy to failure when using a 10-mm triangular graft in a 10-mm tunnel. The 7- and 9-mm screws were superior to the 5.5-mm screws with respect to these same parameters. Based on our results, the 7-mm interference screws can be used with equal confidence as the 9-mm screw, and the 20-mm length can be similarly exchanged for 30-mm length for patellar b-t-b graft fixation.
Publisher: Wiley
Date: 18-08-2011
DOI: 10.1002/JOR.21217
Abstract: The ovariectomized (OVX) rat is widely used in osteoporosis research, but no standard model exists. The in idual effects of rat age, skeletal site, and time post-ovariectomy (post-OVX) on bone have been examined. However, the relationship between them is not yet fully explored. This study examined how various combinations of rat age, skeletal site, and time post-OVX affect bone mineral and microarchitecture. The rats used were 12 (n = 28), 24 (n = 28), and 44 (n = 31) weeks old. In each age group, approximately half underwent OVX and other half underwent Sham surgeries. Bone mineral (content and density) and trabecular morphology was assessed at 2, 5, 10, 15, 20, 25, and 30 weeks post-surgery. Sites examined included the proximal tibia, spine, distal femur, and proximal femur. Overall, the proximal tibia showed the earliest and greatest differences between OVX and Sham groups. The 24-week-old group showed the best osteoporotic response. The 12-week-old group showed growth effects, whilst the 44-week-old group showed aging effects. The response of certain sites to OVX was also found to depend on the rat age used. These findings may aid in explaining discrepancies reported in the literature as well as synergistic combinations that may signify advanced conditions. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:189-196, 2011.
Publisher: Open Medical Publishing
Date: 21-02-2017
DOI: 10.4081/OR.2017.6989
Abstract: Hamstring tendon autografts are used for reconstruction of the anterior cruciate ligament. This study tested the hypothesis that a 5-strand hamstring autograft construct is superior in strength to a 4-strand construct. Four-strand and 5-strand tendon grafts constructs were prepared from ovine flexor tendons and then tested in a uniaxial electromechanical load system with suspensory fixation. The 4-strand and 5-strand constructs were pre-conditioned, stressrelaxed and loaded to ultimate failure. Stress-relaxation, stiffness and ultimate load were compared using a one-way ANOVA. There were no statistical differences in stress-relaxation, initial stiffness, secondary stiffness or ultimate load between 4-strand and 5-strand split tendon graft constructs. Inconsistent failure patterns for both 4-strand and 5-strand constructs were observed. The additional strand in the 5-strand construct may be shielded from stress with additional weakness secondary to the use of suspensory fixation. The potential biological benefit of religamentization and bony integration, with more autologous tissue in the intra-articular space and bony tunnels remains unknown.
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.JHSA.2008.07.010
Abstract: Lag screw fixation is reported to provide the most biomechanically stable construct for fixation of oblique or spiral metacarpal fractures. Lag screws are inserted after overdrilling the proximal cortex, resulting in compression at the fracture site. Minor drilling errors can result in poor screw purchase, instability, and ultimately impaired fracture healing. In an in vitro study, we compared construct stability provided by nonlagged and lagged screw fixation. A cadaveric human metacarpal model was used. After removing the soft tissue, long oblique osteotomies were made in 24 metacarpals, which were then randomized to lagged or nonlagged fixation. Nonlagged fixation was performed through a newly introduced reduction system. Fixed specimens were subjected to biomechanical analysis by way of cantilevered bending to failure, and calculations were made for axial stress and normalized stiffness. All specimens failed in a typical manner through the proximal screw site. Nonlagged compared with lagged screw fixation resulted in a higher axial stress and normalized stiffness, although the differences did not reach statistical significance. Nonlagged screw fixation with use of a precompression device provided comparable fracture site stiffness and biomechanical stability without use of lag screws while removing the requirement for overdrilling, thus simplifying the technique.
Publisher: Public Library of Science (PLoS)
Date: 02-12-2014
Publisher: Springer Science and Business Media LLC
Date: 25-04-2015
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.ARTH.2007.12.016
Abstract: We report the average 10-year clinical and radiographic results of 28 hips with Crowe III or IV developmental dysplasia of the hip (DDH) and a technically difficult primary hip arthroplasty using the cementless modular S-ROM stem (DePuy Orthopedics, Warsaw, Ind). Twenty-one patients required significant autologous bone grafting, 1 had a large allograft, and 6 patients required femoral shortening at the time of their total hip arthroplasty. Three patients had an intraoperative technical complication. The average preoperative Harris hip score was 37 at 10 years, 81. The Short Form 12 was 41.64 physical/54.03 mental at 10 years, and the WOMAC average score was 23 at 10 years. None of the S-ROM stems had been revised or were loose at latest follow-up. Six hips had osteolysis in Gruen zones 1 or 7 but none around or distal to the sleeve. The 10-year results of the S-ROM stem used in patients with osteoarthritis secondary to severe DDH are excellent.
Publisher: Elsevier BV
Date: 04-1998
DOI: 10.1016/S0749-8063(98)70143-4
Abstract: The initial fixation properties of bioresorbable polylactic acid (PLA) interference screws designed for anterior cruciate ligament reconstruction were evaluated using an in vitro bovine model. The surgical technique of interference screw fixation of the bone-patellar tendon-bone autograft complex performed clinically was reproduced in an adult bovine model. The reconstructed knee was tested oriented in 30 degrees of flexion to allow examination of the femoral and tibial fixation properties simultaneously. This model examined the initial fixation strength between PLA and metal interference screws as well as a partially degraded PLA implant. Data from this in vitro model indicate that PLA interference screws can provide similar initial fixation at both time 0 and after degradation for up to 28 days compared with metal interference screws for bone-tendon-bone ACL reconstructions.
Publisher: Springer Science and Business Media LLC
Date: 14-05-2020
DOI: 10.1186/S13018-020-01696-5
Abstract: What is the right surface for an implant to achieve biological fixation? Surface technologies can play important roles in encouraging interactions between the implant surface and the host bone to achieve osseointegration. Preclinical animal models provide important insight into in vivo performance related to bone ongrowth and implant fixation. A large animal model was used to compare the in vivo response of HA and plasma-sprayed titanium coatings in a well-reported adult ovine model to evaluate bone ongrowth in terms of mechanical properties in cortical sites, and histology and histomorphometry in cortical and cancellous sites at 4 and 12 weeks. Titanium plasma-sprayed surfaces outperformed the HA-coated s les in push-out testing in cortical sites while both surfaces supported new bone ongrowth and remodeling in cortical and cancellous sites. While both HA and Ti plasma provided an osteoconductive surface for bone ongrowth, the Ti plasma provided a more robust bone-implant interface that ideally would be required for load transfer and implant stability in the longer term.
Publisher: International Society of Endovascular Specialists
Date: 10-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2017
DOI: 10.1097/PRS.0000000000003247
Abstract: Breast augmentation surgery poses many challenges, and meeting the patient’s expectations is one of the most important. Previous reports equate 100 cc to a one-cup-size increase however, no studies have confirmed this between commercially available bras. The aim of this study was to identify the volume increase between cup sizes across different brands and the relationship with implant selection. Five bra cup sizes from three different companies were analyzed for their volume capacity. Three methods were used to calculate the volume of the bras: (1) linear measurements (2) volume measurement by means of water displacement and (3) volume calculation after three-dimensional reconstruction of serial radiographic data (computed tomography). The clinical arm consisted of 79 patients who underwent breast augmentation surgery from February 1, 2014, to June 30, 2016. Answers from a short questionnaire in combination with the implant volume were analyzed. Across all three brands, the interval volume increase varied between sizes, but not all were above 100 cc. There was some variation in the volume capacity of the same cup size among the different brands. The average incremental increase in bra cup size across all three brands in the laboratory arm was 135 cc. The mean volume increase per cup size was 138.23 cc in the clinical arm. This article confirms that there is no standardization within the bra manufacturing industry. On the basis of this study, patients should be advised that 130 to 150 cc equates to a one-cup-size increase. Bras with narrower band widths need 130 cc and wider band widths require 150 cc to increase one cup size.
Publisher: SAGE Publications
Date: 04-2006
DOI: 10.1016/J.JHSB.2005.09.024
Abstract: Zone 2 flexor tendon repairs can require “venting” or partial resection of the A2 and/or A4 pulleys. We propose and biomechanically assess a technique used by the authors in which the A2 and A4 pulleys are ided and repaired using a V–Y plasty. Two groups of cadaveric fingers were used, one group for assessing the A2 pulley and the second for assessing the A4 pulley. Prepared fingers were mounted onto custom-made jigs, tested using a servohydraulic testing machine and assessed for load to failure. The loads obtained were 75N (SD = 26N) and 234N (SD = 73N) for the A4 and A2 pulleys, respectively. These loads are well in excess of those one would anticipate during a postoperative active mobilization protocol. Tendon pulley V–Y plasty creates a mechanically sound pulley and maintains sufficient cover of the underlying tendon. This technique provides access to perform a tendon repair and/or permits free tendon gliding post-repair, thus providing an attractive alternative to simply “venting”, or resecting, an otherwise troublesome pulley.
Publisher: SAGE Publications
Date: 22-12-2013
Publisher: Wiley
Date: 22-05-2021
DOI: 10.1002/JOR.24714
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.SPINEE.2022.01.003
Abstract: Cage subsidence remains a serious complication after spinal fusion surgery. Novel porous designs in the cage body or endplate offer attractive options to improve subsidence and osseointegration performance. To elucidate the relative contribution of a porous design in each of the two major domains (body and endplates) to cage stiffness and subsidence performance, using standardized mechanical testing methods, and to analyze the fusion progression via an established ovine interbody fusion model to support the mechanical testing findings. A comparative preclinical study using standardized mechanical testing and established animal model. To isolate the subsidence performance contributed by each porous cage design feature, namely the stress-optimized body lattice (vs. a solid body) and microporous endplates (vs. smooth endplates), four groups of cages (two-by-two combination of these two features) were tested in: (1) static axial compression of the cage (per ASTM F2077) and (2) static subsidence (per ASTM F2267). To evaluate the progression of fusion, titanium cages were created with a microporous endplate and internal lattice architecture analogous to commercial implants used in subsidence testing and implanted in an endplate-sparing, ovine intervertebral body fusion model. The cage stiffness was reduced by 16.7% by the porous body lattice, and by 16.6% by the microporous endplates. The porous titanium cage with both porous features showed the lowest stiffness with a value of 40.4±0.3 kN/mm (Mean±SEM) and a block stiffness of 1976.8±27.4 N/mm for subsidence. The body lattice showed no significant impact on the block stiffness (1.4% reduction), while the microporous endplates decreased the block stiffness significantly by 24.9% (p<.0001). All segments implanted with porous titanium cages were deemed rigidly fused by manual palpation, except one at 12 weeks, consistent with robotic ROM testing and radiographic and histologic observations. A reduction in ROM was noted from 12 to 26 weeks (4.1±1.6° to 2.2±1.4° in lateral bending, p<.05 2.1±0.6° to 1.5±0.3° in axial rotation, p<.05) and 3.3±1.6° to 1.9±1.2° in flexion extension, p=.07). Bone in the available void improved with time in the central aperture (54±35% to 83±13%, p<.05) and porous cage structure (19±26% to 37±21%, p=.15). Body lattice and microporous endplates features can effectively reduce the cage stiffness, therefore reducing the risk of stress shielding and promoting early fusion. While body lattice showed no impact on block stiffness and the microporous endplates reduced the block stiffness, a titanium cage with microporous endplates and internal lattice supported bone ingrowth and segmental mechanical stability as early as 12 weeks in ovine interbody fusion. Porous titanium cage architecture can offer an attractive solution to increase the available space for bone ingrowth and bridging to support successful spinal fusion while mitigating risks of increased subsidence.
Publisher: British Editorial Society of Bone & Joint Surgery
Date: 07-2012
DOI: 10.1302/0301-620X.94B7.29115
Abstract: We analysed 54 alumina ceramic-on-ceramic bearings from total hip replacements retrieved at one centre after a mean duration of 3.5 years (0.2 to 10.6) in situ. These implants were obtained from 54 patients (16 men and 38 women) with a mean age of 67 years (33 to 88) who underwent revision for a variety of reasons. Posterior edge loading was found in the majority of these retrievals (32 out of 54). Anterosuperior edge loading occurred less often but produced a higher rate of wear. Stripe wear on the femoral heads had a median volumetric wear rate of 0.2 mm 3 /year (0 to 7.2). The wear volume on the femoral heads corresponded to the width of edge wear on the matching liner. Anteversion of the acetabular component was found to be a more important determinant than inclination for wear in ceramic bearings. Posterior edge loading may be considered to be a normal occurrence in ceramic-on-ceramic bearings, with minimal clinical consequences. Edge loading should be defined as either anterosuperior or posterior, as each edge loading mechanism may result in different clinical implications.
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.ARTHRO.2005.09.003
Abstract: To assess the effect of suture material, anchor orientation, and anchor eyelet design on the static loading properties of suture anchors. Biomechanical bench study. Two metallic suture anchors, Mitek GII (Mitek, Westwood, MA) and Corkscrew (Arthrex, Naples, FL) and a bioabsorbable anchor (Biocorkscrew Arthrex) were tested with single strand of No. 2 Ethibond (Ethicon, Norderstedt, Germany) or No. 2 FiberWire (Arthrex) suture. Suture pull angle was varied through 0 degrees, 45 degrees, and 90 degrees with the anchor rotation angle in either a sagittal or coronal plane. Constructs were tested to failure using an MTS 858 Bionix testing machine (Material Testing Systems, Eden Prairie, MN). Peak loads, stiffness, energy to peak load, and failure modes were determined for all s les. FiberWire showed superior static mechanical properties when compared with single-strand Ethibond over all testing conditions (P < .05). Suture pull angle had a significant effect on load to failure with both metallic anchors but not on the bioabsorbable anchor (P < .05). Suture pull angle and anchor rotation angle play an important role in the failure load of suture when placed in an eyelet. The polyaxial nature of the Biocorkscrew eyelet allows for increased degrees of freedom but introduces failure of the suture eyelet as a new failure mode. The loading direction and placement of the suture anchor plays a role in the performance of the suture anchor-suture complex.
Publisher: Elsevier BV
Date: 12-2009
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.JOCN.2015.05.064
Abstract: With the potential of bias from subjective evaluation scores in spine surgery, there is a need for practical and accurate quantitative methods of analysing patient recovery. In recent years, technologies such as accelerometers and global positioning systems have been introduced as potential objective measures for pain and symptoms following spine surgery. Overall, this perspective article aims to discuss and critique currently utilised methods of monitoring spine surgical outcomes. After analysing current modalities it will briefly analyse new potential methods before examining the place for accelerometers in the field of spine surgery. A literature review was performed on the use of accelerometers for objective evaluation of symptoms and disability after spine surgery, and perspectives are summarised in this article. Physical activity measurement with the use of accelerometers following spine surgery patients is practical and quantitative. The currently available accelerometers have the potential to transform the way functional outcomes from spine surgery are assessed. One key advantage is the collection of standardised objective measurements across studies. Future studies should aim to validate accelerometer data in relation to traditional measures of functional recovery, patient outcomes, and physical activity.
Publisher: Elsevier BV
Date: 11-2015
Publisher: Springer Science and Business Media LLC
Date: 10-2003
DOI: 10.1007/S00192-003-1041-8
Abstract: Synthetic suburethral slings have recently become popular despite the risk of erosion commonly associated with synthetic implants. Some of these materials seem to have unexpectedly low erosion rates. Based on the hypothesis that erosion is due, in part, to biomechanical properties, we undertook an in vitro study. The biomechanical properties of eight non-resorbable synthetic implant materials, stiffness (slope, N/mm) and peak load (N) were determined from load vs. displacement curves. Open-weave Prolene mesh showed unique biomechanical properties compared to other tested materials. The tension- free vaginal tape had the lowest initial stiffness (0.23 N/mm), i.e. low resistance to deformation at forces below the elastic limit, whereas the stiffest implant tested, a nylon tape, reached 6.83 N/mm. We concluded that the TVT and other wide-weave Prolene tapes have unique biomechanical characteristics. These properties may be at least partly responsible for the apparent clinical success of the implants.
Publisher: Elsevier BV
Date: 04-1993
DOI: 10.1016/0142-9612(93)90050-C
Abstract: Electrical potentials are dependent on the properties of the solid and fluid phases of bone. The solid phase in bone is composed of an organic matrix and inorganic bone mineral fibre, while the fluid phase is separated into compartments associated with the vascular channel system and mineralized matrix. Recently, a piezoelectric and electrokinetic response following mechanical deformation was demonstrated in fully hydrated bone. However, alterations in the fluid phase and the effects on streaming potentials where flow through the s le due to pressure on the fluid phase without prior solid matrix mechanical deformation have not been examined. Streaming potentials in high ionic strength solutions reveal a flow-dependent streaming potential in the absence of mechanical deformation not previously observed in stress-generated potentials. Streaming potentials in high ionic strength sodium chloride solutions (0.75 M) of control and deproteinized s les suggest that organic molecules and ions in the electrical double layer may be susceptible to flow-induced alterations which can modify the streaming potentials generated. Alterations in properties of the fluid phase can modify the streaming and zeta potentials and may play a role in the biofeedback response to bone tissue.
Publisher: Springer Science and Business Media LLC
Date: 19-12-2005
DOI: 10.1007/S00167-003-0461-9
Abstract: The reconstruction of a tendon-bone interface, as in rotator-cuff repairs, remains a challenging surgical problem. There is however, little data to show what effect joint position or repair loading under physiological conditions have on the repaired tendon-bone interface. A change in the amount of contact area or load at the tendon-bone interface may influence healing. In this study we investigated the effect of limb position and boundary conditions on the tendon-bone interface in an in vitro rabbit tendon-bone repair model using both unlinked and linked suture repairs.
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 02-1994
DOI: 10.1016/0142-9612(94)90070-1
Abstract: The suitability of polymeric biomaterials as surfaces for the attachment and growth of cells has often been investigated in cell culture. In this study the contribution that serum fibronectin (Fn) or vitronectin (Vn) make to the attachment and spreading of cells cultured from explanted human bone (bone-derived cells) during the first 90 min of culture was determined for metallic and ceramic surfaces. The requirement for Fn or Vn for attachment and spreading of bone-derived cells onto stainless steel 316 (SS), titanium (Ti) and alumina (Al2O3) and to polyethyleneterephthalate (PET) was directly tested by selective removal of Fn or Vn from the serum prior to addition to the culture medium. Attachment and spreading of bone-derived cells onto SS, Ti and Al2O3 surfaces were reduced by 73-83% when the cells were seeded in medium containing serum from which the Vn had been removed. Cell attachment and spreading on these surfaces when seeded in medium containing Fn-depleted serum (which contained Vn) were not reduced to the same extent as in the medium containing Vn-depleted serum. The bone-derived cells failed to attach to the surfaces to the same extent when seeded in medium containing serum depleted of both Vn and Fn. Our results show that for human bone-derived cells, the attachment and spreading of cells onto SS, Ti and Al2O3 as well as PET during the first 90 min of a cell culture attachment assay are a function of adsorption of serum Vn onto the surface.
Publisher: World Scientific Pub Co Pte Lt
Date: 21-09-2015
DOI: 10.1142/S0218810415400092
Abstract: Background: This study investigated the exact failure mechanisms of the most commonly used conventional tendon repair techniques. A new method, radiographing repair constructs in antero-posterior and lateral projections before and after tensioning was used. This allowed to precisely analyse failure mechanisms in regards to geometrical changes in all three dimensions. Additionally the biomechanical stability focusing on gapping was tested. Methods: Sheep fore limb deep flexor tendons were harvested and ided in eight groups of ten tendons. Three common variants of the Kessler repair method and four common 4-strand repair techniques were tested. Additionally a new modification of the Adelaide repair was tested. Results: Biomechanical testing showed no significant differences in gapping for the three tested 2-strand Kessler repair groups. Once a double Kessler or 4-strand Kessler repair was performed the stability of the repair improved significantly. Further significant improvements in biomechanical stability could be achieved by using cross locks in the repair like in the Adelaide repair method. Qualitative analysis using radiographs showed that all Kessler repair variants unfolded via rotations around the transverse suturing component, no matter which variant was used. Conclusions: Additional to the commonly described constriction of the repair construct, the rotating deformation is the main reason for repair site gapping in Kessler tendon repair methods. The term “locking” in a Kessler repair is misleading. The cruciate repairs tended to loose grip and drag (cheese-wire) through the tendon and therefore lead to gapping. The most stable repair constructs in all three dimensions were the Adelaide repair and its interlocking modification. This is due to the superior anchoring qualities of its cross locks and three dimensional stability.
Publisher: Wiley
Date: 13-12-2007
DOI: 10.1002/JBM.A.30913
Abstract: An initial study showed that morselized human bone grafts were osteoconductive and osteoinductive when implanted in nude rat tibial window defects, and 25 kGy of gamma-irradiation significantly reduced those properties. The mechanism of the osteoinductivity and the influence of gamma-irradiation required further investigation. In this study we assessed the paraffin sections of seven morselized human bone grafts implanted into rat tibial defects for 3 weeks after being treated with 0, 15, or 25 kGy gamma-radiation respectively. Osteoclast-like cell counting and protein expressions of bone morphogenetic protein-7 (BMP-7), core binding factor alpha1 (CBFA1), and proliferating cell nuclear antigen (PCNA) were investigated and the positive signals were quantitatively analyzed. More new bone formation was observed in the 0 and 15 kGy groups compared with 25 kGy groups. The newly formed bones were found mainly from the intact cortex into the defects bridged by the implanted grafts. A dense staining of BMP-7 and CBFA1 was noted in the osteoblast-like cells in those areas. The BMP-7 and CBFA1 staining was also seen in the cells surrounding the implanted grafts in the centre areas of the defects in distance from the intact cortex. Quantitative analysis of immunohistochemical staining of the centre areas of the defects showed that gamma-irradiation (15 and 25 kGy) significantly reduced the expression of CBFA1 and BMP-7. In conclusion, morselized human bone grafts may contain some factors, which induced osteoblast lineage differentiation and bone formation and gamma-irradiation damages those bone inducing factors.
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.ARTHRO.2005.09.010
Abstract: To compare the mechanical properties of tendon and capsule after radiofrequency (RF) energy treatment. An in vitro study. RF energy was applied to ovine extensor tendon and human cadaveric glenohumeral capsule varying in the treatment wattage and time (5, 10, or 20 W for 10 or 30 seconds). The associated tissue length changes and dynamic and failure properties of the tissues were investigated using a materials testing machine. Length changes in the 2 tissues were comparable across the range of treatment settings used with both increases in the treatment wattage and time increasing the amount of tissue shrinkage observed. However, tendon showed greater changes in its mechanical properties after RF treatment, with significant decreases in the failure properties of the tissue as well as the dynamic and static stiffness. RF treatment shrinks collagenous tissues in a progressive manner correlated to the treatment wattage. However, it has different effects on the mechanical properties of tendon and capsule with the properties of tendinous tissues dramatically reduced. RF treatment has been shown to effect the mechanical properties of different collagenous tissues differently therefore, it must be used specifically and with caution around areas of mixed tissue origin.
Publisher: SAGE Publications
Date: 27-09-2010
Publisher: Springer Science and Business Media LLC
Date: 10-2001
DOI: 10.1007/S00464-001-0036-0
Abstract: Very high pressures are generated at the interface between the tip of laparoscopic graspers and tissue. The pressure profile suggests that the high pressure is due to stress concentration at the edge of the jaw. Stress concentration at an edge can be modified by curving the edge. This study sought to determine the effect of a curved edge on pressures generated by the jaw of a laparoscopic grasper. Pressure generated at the instrument tissue interface was measured by a thin film pressure transducer. The two instruments that we compared were identical in every respect except the profile of the jaw edge. One was unmodified the other had a rounded grasping edge. Load and handle pressure were constant throughout. Tissue pressures generated by the grasper were recorded as the angle of load was increased from vertical (0 degrees ) to 135 degrees. Localized pressures at the tip of the unmodified instrument reached a maximum of 1500 kPa. Pressures at the tip of the curved instrument reached a maximum of 920 kPa under identical conditions. High pressures generated at the tip of laparoscopic graspers can be reduced by rounding the edge of the jaw.
Publisher: Georg Thieme Verlag KG
Date: 23-01-2023
Abstract: Objective The aim of this study was to determine the effect of a unicortical defect at either the mid-diaphysis (MD) or distal metaphysis (DM) on the torsional properties of tibiae in an in vitro rabbit model, and to further examine optimal distal jig pin position for the canine tibial plateau levelling osteotomy (TPLO) procedure. Study Design Thirty-eight tibiae from 19 skeletally mature female New Zealand White rabbits were assigned to one of three groups Group 1: intact, Group 2: MD defect and Group 3: DM defect. Defects were created using a 1.6 mm Ellis pin. Pure torsion was applied to each s le and peak torque and angular displacement recorded. Results All tibiae fractured in a spiral configuration. Fracture lines involved the defect in 33% of the MD s les and 0% of the DM s les. No differences were detected for peak torque and stiffness between groups. However, energy (mean ± standard deviation) was significantly reduced (p = 0.028) in the MD group (0.18 ± 0.07) relative to the intact tibia group (0.31 ± 0.14). Angle was also significantly reduced (p = 0.040) in the MD group (0.17 ± 0.05) compared with the intact group (0.23 ± 0.07). Placement of a DM defect had no significant effect on mechanical properties of the rabbit tibiae. Conclusion Defects placed in the MD significantly reduced energy and angle in comparison to intact s les. No significant difference in peak torque or stiffness was observed between groups. If canine tibiae were similarly affected, our findings suggest jig pin placement in the DM to have a lesser effect on the torsional properties of the tibiae.
Publisher: Springer International Publishing
Date: 2016
Publisher: BMJ
Date: 04-2003
Abstract: Large rotator cuff tears are extremely uncommon in young people and when they occur they may be associated with shoulder instability. This paper reports on a series of six elite rugby union and rugby league footballers who presented with shoulder instability and large rotator cuff tears. They were treated with a two stage procedure: an open rotator cuff repair followed by an open shoulder stabilisation some 10 weeks later. All had successful outcomes. The paper also highlights the risk of tearing the rotator cuff when a patient continues to play contact sport with an untreated unstable shoulder.
Publisher: Georg Thieme Verlag KG
Date: 2014
Abstract: Objectives: To evaluate the degree of lateralization achievable and strength of tibial tuberosity transposition and advancement (TTTA) relative to pin and tension band wiring (PTBW) for lateral tibial tuberosity transposition. Methods: Six pairs of cadaveric tibiae were used. Tibial tuberosity position was determined with computed tomography (CT) bones were then randomly assigned into TTTA and PTBW groups. The PTBW group had a tibial tuberosity osteotomy and fixation with pin and tension band wiring. The TTTA group had a tibial tuberosity advancement performed with lateralization of the tibial tuberosity by 50% of cage depth, using spacers on the cranial cage screw. Postoperative CT images showed lateralization and craniocaudal deviation. Single axial distractive loading was applied to the patella at 90° to the tibial plateau, and peak load, energy, and stiffness were calculated. Results: There were significant differences in lateralization (PTBW: 67.92 ± 5.1 % TTTA: 88.51 ± 5.5 %) (p = 0.0173) and craniocaudal deviation (PTBW: –8.30 ± 1.4 % TTTA: 6.83 ± 0.6) (p = 0.0001). There were no significant differences in peak load to failure (N) (PTBW: 1448 ± 121 TTTA: 1597 ± 43) (p = 0.4541), energy to failure (N/mm) (PTBW: 15013 ± 2719 TTTA: 17314 ± 887) (p = 0.646), or stiffness (N/mm)(PTBW: 102.8 ± 4.7 TTTA: 92.9 ± 4.8) (p = 0.2716). Clinical significance: The TTTA was more effective at lateralization of the tibial tuberosity, and of comparable strength to PTBW. Greater support of the osteotomized fragment with TTTA may resist cyclic loading, and requires evaluation.
Publisher: Elsevier BV
Date: 08-2003
DOI: 10.1016/S1010-5182(03)00040-4
Abstract: Vascular endothelial growth factor (VEGF) has recently been found to be essential for hypertrophic chondrocyte apoptosis and angiogenesis at the growth plate of long bones, indicating a central role in endochondral ossification. VEGF has more recently, also been shown to be expressed in articular cartilage chondrocytes in human osteoarthritic and rheumatoarthritic joints but not healthy adult joints. To investigate the role of VEGF in the fibrocartilage of the temporomandibular joint, this study aimed to document the presence and distribution of VEGF in the condylar articular cartilage of sheep temporomandibular joints. Mandibular condyles of the temporomandibular joints of five 18-month old Wether sheep were fixed, decalcified, paraffin embedded and sectioned. The sections were analyzed using immunohistochemistry for VEGF. VEGF was found to be localised predominantly to the proliferative and maturing layers of chondrocytes in the condylar fibrocartilage of the temporomandibular joints. Articular cartilage is an avascular and alymphatic tissue. As such, the localisation of VEGF to the articular cartilage of normal temporomandibular joint condyles suggests a role for VEGF other than angiogenesis. VEGF is shown here for the first time to be present in mandibular condylar cartilage, leading us to propose a possible role in non-angiogenic extracellular matrix remodeling.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-06-2015
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1053/J.JFAS.2007.07.003
Abstract: Treatment of chronic Achilles tendon ruptures can be technically difficult because of tendon retraction, atrophy, and short distal stumps. Surgical repair of chronic Achilles tendon ruptures focuses on local and free tendon transfers, as well as reconstruction with allografts or synthetic materials. This study examined the in vitro mechanical properties of a reconstructed Achilles tendon with the peroneus brevis or the flexor hallucis longus tendons in a human cadaver model. The tendons were harvested from 17 fresh-frozen human cadavers, and the same techniques were used for all of the model reconstructions. Biomechanical measurements included the failure load, stiffness, energy-to-peak load, and mode of failure. The mean failure load was significantly higher in the peroneus brevis group (P = .036), and there was no significant difference in stiffness and energy-to-peak load between the peroneus brevis and flexor hallucis longus groups. In every case, the mode of failure involved the tendon graft pulling through either the distal or proximal stump of the Achilles tendon. The greater failure loads observed with the use of peroneus brevis may not be clinically relevant, however, because of the magnitude of the peak loads observed in the cadaveric model. The present study supports the use of either peroneus brevis or flexor hallucis longus for reconstruction of chronic Achilles tendon ruptures and indicates the need for surgeons to carefully reinforce the attachment of the transferred tendon grafts to the stumps of the Achilles tendon to prevent pullout.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2005
DOI: 10.1097/01.PRS.0000153033.64186.58
Abstract: The authors hypothesized that distraction at a rate of 3 mm/day, compared with mandibular distraction at a rate of 1 mm/day, would produce a maladaptive response in adjacent muscles of mastication. The authors further hypothesized that the maladaptive response would manifest at the single fiber level by means of increased sarcomeric heterogeneity, decreased maximum force output, and increased susceptibility to stretch-induced injury. In an ovine model, distraction osteogenesis of the right hemimandible was performed at either 1 mm/day for 21 days (n = 2) or 3 mm/day for 7 days (n = 2) to achieve a total distraction distance of 21 mm. The left hemimandibles served as controls. After a consolidation period of 2 days, the anterior digastric muscles were harvested in six randomly selected single fibers from each muscle, maximum calcium-activated force (Po) was measured at optimal sarcomere length. The amount of damage to the sarcomeres in each fiber was assessed microscopically. To test susceptibility to contraction-induced injury, each fiber was given an activated stretch of 20 percent. Compared with control fibers and fibers distracted at 1 mm/day, maximum tetanic force (Po) was significantly lower in fibers distracted at 3 mm/day. Compared with control fibers, specific Po (Po/cross-sectional area) was lower in fibers distracted at 3 mm/day. The number of sarcomeres appearing damaged in fibers distracted at 3 mm/day was significantly higher than in control fibers or in fibers distracted at 1 mm/day. A greater deficit in Po was observed after a single activated stretch in fibers distracted at 3 mm/day than in control fibers or in fibers distracted at 1 mm/day. The authors conclude that distraction of the anterior digastric muscle in sheep at 3 mm/day produces a maladaptive response in the muscle fibers but a rate of 1 mm/day is tolerated by the muscle fibers. These data are consistent with the hypothesis that distraction of skeletal muscle at high rates results in increased heterogeneity of sarcomere lengths and that this increase in heterogeneity is the most likely potential mechanism resulting in whole muscle force deficits and in increased susceptibility to stretch-induced injury in distracted muscles.
Publisher: Wiley
Date: 17-11-2010
DOI: 10.1111/J.1445-2197.2010.05570.X
Abstract: What has been missing from current assessment tools post knee arthroplasty is a means by which a patient's mobility and activity levels can be objectively measured over time in a real world setting. The Intelligent Device for Energy Expenditure and Activity (Minisun, Fresno, USA) (IDEEA) is one such device that meets these criteria. It quantifies activity by measuring energy expenditure and records the type of activity performed. The purposes of this study were to (i) determine if there were differences in energy expenditure in different groups of patients at various time points pre- and post-surgery and (ii) determine the correlations between energy expenditure and each of the subjective International Knee Documentation Committee (IKDC), Oxford and Tegner scoring systems. Sixty-five total knee arthroplasty (TKA) patients were recruited into a cross-sectional study to collect energy expenditure and activity data using the IDEEA. Data were collected preoperatively and post-operatively at 6-week, 3-month, 6-month and 12-month time intervals. Energy expenditure and type of activity did not significantly change over the five recording periods. The patients spent <5% of the recording time walking, stepping or in transitions between movements. Energy expenditure showed a low to moderate correlation with the subjective IKDC, Oxford and Tegner questionnaires. Current evaluation questionnaires may not accurately record activity levels and TKA patients spend less time walking than the normal population. We believe the IDEEA is an effective tool for objectively measuring activity and energy expenditure following knee arthroplasty.
Publisher: Research Square Platform LLC
Date: 04-03-2020
DOI: 10.21203/RS.3.RS-15923/V1
Abstract: Background What is the right surface for an implant to achieve biological fixation? Surface technologies can play important roles in encouraging interactions between the implant surface and the host bone to achieve osseointegration. Pre-clinical animal models provide important insight into in-vivo performance related to bone ongrowth and implant fixation. Methods A large animal model was used to compared the in vivo response of HA and plasma sprayed titanium coatings in a well reported adult ovine model to evaluate bone ongrowth in terms of mechanical properties in cortical sites, histology and histomorphometry in cortical and cancellous sites at 4 and 12 weeks. Results Titanium plasma sprayed surfaces outperformed the HA coated s les in push-out testing in cortical sites while both surfaces supported new bone ongrowth and remodeling in cortical and cancellous sites. Conclusions While both HA and Ti plasma provided an osteoconductive surface for bone ongrowth, the Ti plasma provided a more robust bone-implant interface that ideally would be required for load transfer and implant stability in the longer term.
Publisher: Research Square Platform LLC
Date: 08-04-2020
DOI: 10.21203/RS.3.RS-15923/V2
Abstract: Background What is the right surface for an implant to achieve biological fixation? Surface technologies can play important roles in encouraging interactions between the implant surface and the host bone to achieve osseointegration. Pre-clinical animal models provide important insight into in-vivo performance related to bone ongrowth and implant fixation.Methods A large animal model was used to compare the in vivo response of HA and plasma sprayed titanium coatings in a well reported adult ovine model to evaluate bone ongrowth in terms of mechanical properties in cortical sites, histology and histomorphometry in cortical and cancellous sites at 4 and 12 weeks. Results Titanium plasma sprayed surfaces outperformed the HA coated s les in push-out testing in cortical sites while both surfaces supported new bone ongrowth and remodeling in cortical and cancellous sites. Conclusions While both HA and Ti plasma provided an osteoconductive surface for bone ongrowth, the Ti plasma provided a more robust bone-implant interface that ideally would be required for load transfer and implant stability in the longer term.
Publisher: Elsevier BV
Date: 10-2010
DOI: 10.1016/J.JBIOMECH.2010.06.006
Abstract: The assessment of repair site gap formation during cyclic loading of reconstructed flexor tendons provides important data on the performance of repair techniques in the early postoperative period. This study describes our cyclic testing protocol and evaluates the relationship between changes in optical gap and grip-to-grip displacement. Sixteen sheep hind limb deep flexor tendons were randomized into four repair groups (n=4 per group): a 2-strand repair (modified Kessler) and 4-strand repair (Adelaide), both with and without a simple running peripheral suture. Repaired tendons were cycled for 1000 cycles at appropriate rehabilitation loads for the reconstruction. Tendons were paused at 18 pre-determined cycle points to measure gap and displacement. A strong positively linear relationship between gap and displacement was demonstrated for all repair groups (R²>0.90). An initial non-linear region during the first 10 cycles was noted with some combined core and peripheral repairs. Although trends in displacement after 10 cycles can be used to reflect gapping behaviour, direct optical measurement of gap remains preferable. We hypothesized that the adjustment of suture strands and equilibration of forces within the reconstruction occurs mostly during the initial 10 cycles. Gap-cycle curves provide a good illustration of dynamic changes at the repair site, and should be added more frequently to cyclic testing studies.
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/0142-9612(95)93114-S
Abstract: Corticosteroids are known to inhibit collagen synthesis in vitro as well as having a deleterious effect on ligament healing when applied immediately following injury. An acute injection of betamethasone into a transected rabbit medial collateral ligament significantly impaired the biomechanical and histological properties compared to non-injected transected ligaments. Differences in mechanical, histological and biochemical properties were observed up to 3 months following injury and an acute steroid injection. The present study explored the effects of a corticosteroid (betamethasone) injection 7 days following the initial injury. Biomechanical and histomorphometric analyses were carried determine if the previously observed deleterious effects of a corticosteroid injection immediately following injury can be linked to an interference in the inflammatory phase of healing due to the presence of the corticosteroid.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.SPINEE.2018.05.022
Abstract: Degenerative disc disease (DDD) is a common, widespread socioeconomic problem. Appropriate large animal models of DDD are required for improved understanding and to serve as preclinical test beds for therapeutic strategies. To evaluate the effects of short and medium duration immobilization on the sheep lumbar intervertebral disc (IVD) and facet joints (FJs), and to establish a large animal model for DDD research. An in vivo sheep model evaluating the effect of short- and medium-term immobilization on disc degeneration. Eighteen sheep were equally randomized into three groups: short-term (6-week) immobilization (n=6), medium-term (26-week) immobilization (n=6), and control (no surgery) (n=6). Immobilization of L3-L4 was achieved with pedicle screw and rod implantation, the IVD was kept intact, and the annulus and end plates were not disrupted. The IVD and FJs were assessed with planar radiography, computerized tomography (CT), magnetic resonance imaging (MRI), pure moment biomechanical testing, and histologic analysis. Disc height was reduced for 6- and 26-week immobilization groups. The MRI and histologic analysis demonstrated significant disc degeneration for both immobilized groups compared with control, but no statistical difference was detected between short- and medium-term duration. Progressive degenerative changes in FJs were observed with micro-CT and histologic end points. Immobilization significantly reduced lateral bending and flexion-extension range of motion. The mechanical environment set up by immobilization alone is capable of inducing lumbar disc degeneration at both 6 and 26 weeks in sheep. Longer duration immobilization did not advance disc degeneration process beyond of that found with short duration. The present model produces a degenerative disc with intact annulus and without acute injury, more closely representing the scenario common in human disc degeneration. This provides a suitable large animal in vivo model for the evaluation of the new therapies for disc degeneration. Further studies would do well to examine the effect of remobilization after immobilization in this model.
Publisher: British Editorial Society of Bone & Joint Surgery
Date: 09-2016
DOI: 10.1302/2046-3758.59.2000507
Abstract: This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris. The CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p 0.001). The brown/red particles were significantly higher for ASR/SROM (p 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride. This study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage. Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016 :370–378. DOI: 10.1302/2046-3758.59.2000507.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.ARTHRO.2007.01.030
Abstract: The purpose of this study was to compare polylactide carbonate (PLC) interference screws with poly-L-lactide (PLLA) screws in an ovine anterior cruciate ligament reconstruction model. A PLC screw or PLLA screw was placed in the center of a 4-strand soft-tissue autograft fixating the graft within the tibial tunnel. Assessments were made at 6 and 12 weeks for fixation strength and at time points of 6, 12, 26, and 52 weeks via computed tomography and histology. No adverse or inflammatory reactions were noted for either material at any time point. Mechanical fixation strength increased from 6 to 12 weeks for both the PLC and PLLA screws, with no significant differences in fixation strength being found between the 2 groups. By 26 weeks, the PLC screw was partially replaced by new bone, a process that was completed by 52 weeks. The PLLA screws were intact and surrounded by a fibrous layer at 52 weeks with no obvious resorption. New bone formation within the tendon construct located in the bone tunnel proximal to the interference screw was also noted in the PLC screw group but was not observed in the PLLA group. This study has supported the hypothesis that this bioabsorbable composite has sufficient mechanical properties and strength retention to function successfully as an interference screw but also stimulates a biologic healing response, enabling replacement by bone and tunnel healing. This study shows both the satisfactory mechanical characteristics and osteoconductive nature of PLC used in an interference screw in an ovine anterior cruciate ligament reconstruction model.
Publisher: Wiley
Date: 25-10-2010
DOI: 10.1111/J.1445-2197.2010.05339.X
Abstract: The use of a continuous local anaesthesia infusion after laparotomy may reduce opioid requirements and facilitate earlier return of bowel function, independent mobilization and hospital discharge. We performed a double-blinded, randomized controlled trial on 55 patients who underwent laparotomy. Patients were randomly allocated to receive a continuous infusion of either 0.2% ropivacaine or normal saline into their midline abdominal wound at the fascial level. The end points of the study were: total opioid requirements at 24 and 48 h time to first flatus, bowel movement and independent ambulation length of hospital stay complications and daily mean patient-reported pain scores at rest and movement. The two treatment groups were well controlled for factors that influence analgesia requirements, including age, weight, length of wound incision and type of operation. Patients allocated to ropivacaine infusion used, on average, 32 mg less morphine at 48 h (95% confidence interval 7, 57 P= 0.01). This was highly statistically significant after adjusting for age, gender and type of operation (P= 0.0006). Ropivacaine infusion was associated with a significantly decreased time to independent mobilization (P= 0.02), time to first flatus (P= 0.02) and reduced post-operative ileus (2/28 versus 9/27, χ(2) = 5.89, P= 0.02). There was no significant effect of ropivacaine infusion on time to first bowel movement (P= 0.94) nor length of hospital stay (P= 0.77). Local anaesthesia infusion at the fascial plane provides effective analgesia. This improves patient recovery through earlier return to bowel function and mobilization.
Publisher: Springer Science and Business Media LLC
Date: 03-11-2011
Abstract: Uncemented fixation of components in joint arthroplasty is achieved primarily through de novo bone formation at the bone-implant interface and establishment of a biological and mechanical interlock. In order to enhance bone-implant integration osteoconductive coatings and the methods of application thereof are continuously being developed and applied to highly porous and roughened implant substrates. In this study the effects of an electrochemically-deposited dicalcium phosphate dihydrate (DCPD) coating of a porous substrate on implant osseointegration was assessed using a standard uncemented implant fixation model in sheep. Plasma sprayed titanium implants with and without a DCPD coating were inserted into defects drilled into the cancellous and cortical sites of the femur and tibia. Cancellous implants were inserted in a press-fit scenario whilst cortical implants were inserted in a line-to-line fit. Specimens were retrieved at 1, 2, 4, 8 and 12 weeks postoperatively. Interfacial shear-strength of the cortical sites was assessed using a push-out test, whilst bone ingrowth, ongrowth and remodelling were investigated using histologic and histomorphometric endpoints. DCPD coating significantly improved cancellous bone ingrowth at 4 weeks but had no significant effect on mechanical stability in cortical bone up to 12 weeks postoperatively. Whilst a significant reduction in cancellous bone ongrowth was observed from 4 to 12 weeks for the DCPD coating, no other statistically significant differences in ongrowth or ingrowth in either the cancellous or cortical sites were observed between TiPS and DCPD groups. The application of a DCPD coating to porous titanium substrates may improve the extent of cancellous bone ingrowth in the early postoperative phase following uncemented arthroplasty.
Publisher: Georg Thieme Verlag KG
Date: 14-08-2012
Abstract: Platelet Rich Plasma (PRP) therapies require blood to be processed prior to application, however, the full assessment of the output of platelet sequestration devices is lacking. In this study the products of the Autologous Fluid Concentrator (Circle BiologicsTM, Minneapolis, MN) and the Gravitational Platelet Separation System (GPS, Biomet, Warsaw, IN, USA) were evaluated in terms of platelet viability and PRP constituents. The AFC and GPS produced 6.4 (±1.0) ml and 6.3 (±0.4) ml of PRP, with platelet recovery of 46.4% (±14.7%) and 59.8% (±24.2%) producing fold increases of platelets of 4.19 (±1.62) and 5.19 (±1.62), respectively. Fibrinogen concentration was increased above baseline PPP produced with the AFC. pH was lower for both of the processed s les than for whole blood. White Blood Cell count was increased around 5 fold. Functional tests showed preserved viability with both devices. This represents essential knowledge that every treating physician should have before they can confidently administer PRP therapy produced by any method. These are the first published results of platelet function for the GPS system and the first performance results of the AFC system. The PRP produced is classified according to broad classifications as Leukocyte-PRP (L-PRP) for both devices.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2013
Publisher: Elsevier BV
Date: 2013
Publisher: Informa UK Limited
Date: 1993
Publisher: Elsevier BV
Date: 07-2003
DOI: 10.1016/S1350-4533(03)00016-X
Abstract: Wear of the polyethylene (PE) insert in total knee arthroplasty remains a significant problem. The generation of biologically active wear particles may ultimately affect implant longevity through osteolysis or premature/catastrophic PE failure. The rate and pattern of wear is influenced by many factors, including component geometry and in idual loading conditions, which determine the contact surface area and kinematics of the reconstructed knee. Contact areas and stresses at the proximal femoral-PE insert interface and distal PE-tibial interface contact surface areas were measured in nine mobile bearing total knee designs at 0, 30, 60, 90 and 110 degrees of flexion at 3600 N (5 x body weight) using a standardized test method. Proximal and, to a lesser degree, distal interface contact area footprints decreased significantly with increasing flexion angle based on the conformity of the designs, resulting in a corresponding increase in the mean and peak stresses.
Publisher: Informa UK Limited
Date: 15-08-2011
DOI: 10.3109/07357907.2011.606252
Abstract: Type-I insulin-like growth factor receptor (IGF1R) and its signaling play an important role in osteosarcomagenesis, tumor progression, and chemoresistance. The purpose of this study was to investigate both the effect and mechanisms of IGF1R inhibition by tyrphostin AG1024 in the presence or absence of doxorubicin in a panel of six osteosarcoma cell lines and a self-established doxorubicin-resistant cell line. We are the first to indicate that targeting IGF1R together with doxorubicin achieved additive anti-osteosarcoma growth effect, accompanied with increased apoptosis, cytotoxicity, and dual cell cycle arrests. In conclusion, IGF1R inhibition can enhance doxorubicin chemotherapy in some osteosarcoma cell lines.
Publisher: Cold Spring Harbor Laboratory
Date: 09-08-2021
DOI: 10.1101/2021.08.08.455592
Abstract: Mouse hematopoietic stem cells (HSCs) first emerge at embryonic day 10.5 (E10.5) on the ventral surface of the dorsal aorta, by endothelial-to-hematopoietic transition (EHT). We investigated whether cells with mesenchymal stem cell-like activity, which provide an essential niche for long-term HSCs (LT-HSCs) in the bone marrow, reside in the aorta- gonad-mesonephros (AGM) and contribute to the structural development of the dorsal aorta and EHT. Using transgenic mice, we demonstrate a lineage hierarchy for AGM stromal cells and traced the E10.5/E11.5 aortic endothelium and HSCs to mesoderm derived ( Mesp1 ) PDGFRA + stromal cells ( Mesp1 der PSCs). Mesp1 der PSCs dominate the sub-endothelial and ventral stroma in the E10.5–E11.5 AGM but by E13.5 were replaced by neural crest ( Wnt1 ) derived PDGFRA + stromal cells ( Wnt1 der PSCs). Co-aggregating non-hemogenic embryonic and adult endothelial cells with Mesp1 der PSCs but not with Wnt1 der PSCs resulted in activation of a hematopoietic transcriptional program in endothelial cells accompanied by EHT and generation of LT-HSCs. Dose-dependent inhibition of PDGFRA signalling or BMP, WNT, NOTCH signalling interrupted this reprogramming event. This partnership between endothelial cells and AGM Mesp1 der PSCs could potentially be harnessed to manufacture LT-HSCs from endothelium.
Publisher: International Society of Endovascular Specialists
Date: 04-2014
DOI: 10.1583/13-4530MR.1
Publisher: SAGE Publications
Date: 07-2015
Abstract: A synthetic device for ACL reconstruction has long been sought to eliminate co-morbidities of autograft harvest, and variability, potential for disease and allogeneic reaction with allograft. We hypothesized that a PLLA graft and hamstring autograft would regenerate similarly in an ovine model of ACL rupture. 125 ACL reconstructions were performed with PLLA grafts in 79 sheep and autograft tendons in 46 sheep. 3 combinations of fixation were used: (1) titanium screws outside-in on tibia, inside-out on femur, (2) screws outside-in on tibia & femur, (3) screw outside-in on the femur, suspension fixation on femur. The PLLA graft was made of 3-D braided fibers with loose braid intra articularly and tight braid for fixation. ACL reconstructions were evaluated 6 weeks through 4 years for clinical function, synovitis, serology, gross reaction, scoring of cartilage and menisci, histology, radiography, micro-CT, MRI, and pathology of organs. Strength of the BLB complex was measured at 6 weeks, and 6 and 12 months. Sheep with PLLA grafts were fully functional post-op autograft sheep exhibited early morbidity. There was no evidence of synovitis, serology and gross findings were normal. Micro CT, radiographs, MRI, and histology indicated resorption of PLLA grafts and regeneration of the ACL at 12 months. Intra articular histology of PLLA- and auto- grafts showed neo-ligamentization at 3 months, increased collagenous deposition and cellularity with time, a reconstituted ACL at 1 year, and continued maturation. Intra-articularly, PLLA grafts were intact at 6 weeks, and 3 & 6 months, and nearly fully resorbed at 1 year. Histology in the tibial bone tunnel (6 - 48 months) showed the PLLA graft between the screw and aperture filled with new collagenous tissue and tendon-bone healing. At 18, 24, and 48 months, PLLA grafts were intact and encapsulated by bone. Pathology of lymph nodes and organs indicated occasional presence of PLLA particulate. Histology and pathology yielded no adverse findings locally, systemically, or functionally. Biomechanical testing of BLB complexes with inside-out screw fixation on the femur (1) was found to impede healing and function of the PLLA graft. Testing of sheep with suspension fixation (3) showed PLLA grafts to bear a load of 423N (n=6, SD 119N) at 6 weeks, 491N (n=5, SD 116N) at 6 months, and 386N (n=6, SD 220N) at 12 months. In comparison, autograft at 6 weeks, 6 months, and 12 months failed at 111N (n=5, SD 40N), 526N (n=3, SD 185N), and 525N (n=5, SD 171N), respectively. Outside-in fixation for the tibia and femur (2) showed the PLLA graft to bear loads at 6 and 12 months of 320N (n=6, SD 142N) and 601N (n=6, SD 186N). Autograft failed at loads of 358N (n=1) and 422N (n=3, SD 164N). Histology was consistent for autograft and PLLA grafts, which is ascribed to the PLLA resembling autograft in early load bearing, gradual resorption and consequent load transfer to newly formed tissue (absence of stress shielding), and maturation of tissue. The difference in resorption in the bone tunnels versus intra articularly is ascribed to the more vascular, biologically dynamic environment of the ACL. Reliable fixation for the PLLA graft was achieved with outside-in screw fixation. Inside-out screw fixation is a contraindication. This is the first study to demonstrate regeneration of the ACL, resorption of an implant intra articularly using a bioresorbable polymer, and is the longest in-vivo evaluation of PLLA in ligament repair of which we are aware.
Publisher: Wiley
Date: 12-03-2014
DOI: 10.1002/JOR.22588
Publisher: Elsevier BV
Date: 04-2002
Abstract: This study examined the role of substrate preparation and hydroxyapatite (HA) coating thickness on bone ongrowth and shear strength in a bilateral bicortical sheep model. Plasma-sprayed and grit-blasted titanium implants with different thickness HA coatings were examined at 4, 8, 12, and 26 weeks after implantation. Shear strength increased with time for all implants. Plasma-sprayed implants were superior to grit-blasted implants at all time points. The 100-microm-thick HA layer used in the present study provided greater fixation and ongrowth and less resorption compared with the 50-microm-thick layer. We did not observe any advantage in using a thicker HA coating for the titanium substrates examined.
Publisher: SAGE Publications
Date: 28-11-2012
Abstract: Post-operative patellar tendon shortening induces a distal positioning of the patella in the femoral trochlear groove, which has been associated with pain and impeded mobility. An idealized in vitro model was used to examine the effects of shortening on patellar kinematics. The PT length was progressively reduced by up to 5 mm (1-mm instalments) using a device secured onto the tendon in n = 9 ovine stifles. In vitro 6 degrees-of-freedom motion data for the patellofemoral and tibiofemoral joints under conditions of passively induced flexion–extension was acquired electromagnetically. Patellar motion was analysed as a function of both tibial and patellar flexion angles relative to the femoral co-ordinate frame. Linear regression with contrasts was used to compare kinematic changes for each shortening level, with significance set at P .01. A mean maximum percentage length reduction of 8.2% was achieved. Patellar flexion was linearly correlated with tibial flexion angle in the intact joint, and this correlation persisted after tendon shortening (R = 0.977, P 0.01). Patellar kinematics expressed as a function of tibial flexion angle were significantly altered by a mean length decrease of 8.2%, while flexion and proximo-distal shift patterns were significantly affected at lesser shortening levels of 3.1% and 4.7%, respectively. Patellar kinematics expressed as a function of patellar flexion angle remained unchanged. These results suggest that patellar motion within the trochlear groove in the ovine stifle joint follows a repeatable three-dimensional path and that patellar tendon shortening advances the position of the patella along this path, without significantly altering it.
Publisher: Spandidos Publications
Date: 06-02-2012
DOI: 10.3892/OR.2012.1675
Abstract: Sorafenib is an oral multikinase inhibitor that acts by inhibiting tumor growth and disrupting tumor microvasculature through antiproliferative, anti-angiogenic and proapoptotic effects. It exerts these effects via inhibition of multiple targets including Raf serine/threonine kinases, vascular endothelial growth factor receptor tyrosine kinases VEGFR-1, VEGFR-2, VEGFR-3 and platelet-derived growth factor receptor β (PDGFR-β). Current literature shows that the deregulated signaling through these receptors is commonly seen in human tumors. In addition, sorafenib is also shown to induce apoptosis through downregulation of Mcl-1 in many cancer types. Hence, sorafenib as a single agent has shown promising activity in some cancers such as renal cell carcinoma (RCC), hepatocellular carcinoma (HCC) and thyroid cancers. Currently, the drug holds FDA approval for the treatment of advanced RCC and unresectable HCC. However, many clinical studies have indicated several limitations to the application of sorafenib as a single agent in various other cancers. Owing to these reasons and the potential of sorafenib to synergize with other anticancer therapies, its combination with other targeted agents and chemotherapy has been widely explored with promising results. In addition, it has also shown synergistic results when combined with radiation. This review summarizes the current basic and clinical studies on the effects and mechanisms of sorafenib either administered alone or in combination with other anticancer treatments.
Publisher: Georg Thieme Verlag KG
Date: 06-09-2022
Abstract: The study aims to evaluate the biomechanical properties of feline femora with craniocaudal screw-hole defects of increasing diameter, subjected to three-point bending and torsion to failure at two different loading rates. Eighty femoral pairs were harvested from adult cat cadavers. For each bending and torsional experiment, there were five groups ( Defect size to bone diameter ratio was significantly different between defect groups within bending and torsional experiments respectively (intact [0% 0%], 1.5 mm [17.8% 17.1%], 2.0 mm [22.8% 23.5%], 2.4 mm [27.8% 27.6%], 2.7 mm [31.1% 32.4%]) ( Screw-hole defects up to 2.7 mm did not significantly reduce feline bone failure properties in this
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.INJURY.2007.11.286
Abstract: Non-perpendicular drilling of bone is commonplace in orthopaedic surgery. In the absence of drill-jigs and guides, the drill-tip is prone to skiving along the bone. Skiving can alter the position of the intended hole or result in damage to surrounding tissues. We hypothesised that the acute point-angle and increased flexural rigidity of 3-fluted drills - in certain clinical scenarios - can increase a surgeons' ability to accurately position a hole. This study examined differences in drill-tip geometry (point-angle) and mechanical properties (flexural rigidity) between 2.8mm diameter 2-fluted and 3-fluted surgical drills. Our results show that the 3-fluted design offers a significant improvement over the 2-fluted design not only in terms of accuracy at 15 degrees and 30 degrees approach angles the 3-fluted drill skived significantly less than the 2-fluted drill in the hands of our surgeon, but also in the range of permissible approach angles the 3-fluted drill was able to drill at a 45 degrees approach angle with skiving equivalent to that experienced by the 2-fluted drill at 15 degrees . Mechanical testing showed that bending stiffness (N/mm) of the 3-fluted drill (9.5+/-2.1N/mm) is more than double that of the 2-fluted drill (3.5+/-0.6N/mm) during operation. Computer modeling of the drills supported this finding and demonstrated that bending stiffness (I X) for the 2-fluted drill varies dynamically during operation whilst remaining constant for the 3-fluted drill. Our study confirms a correlation between mechanical properties, point-geometry and targeting capability for surgical drills. Increased I X of 3-fluted drills may account for the clinical prevalence of rotational bending failure amongst 2-fluted drills.
Publisher: British Editorial Society of Bone & Joint Surgery
Date: 04-2008
DOI: 10.1302/0301-620X.90B4.19718
Abstract: This prospective study presents the ten-year (5 to 16) clinical and radiological results of 55 primary total hip replacements (THR) using a cementless modular femoral component (S-ROM). All patients had a significant anatomical abnormality which rendered the primary THR difficult. The mean Harris hip score was 36 (12 to 72) pre-operatively, 83 (44 to 100) at five years, and 85 (45 to 99) at ten years. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) and short-form (SF)-12 scores were recorded from the year 2000. The mean SF-12 score at five years after surgery was 45.24 (22.74 to 56.58) for the physical component and 54.14 (29.20 to 66.61) for the mental component. By ten years the SF-12 scores were 42.86 (21.59 to 58.95) and 51.03 (33.78 to 61.40), respectively. The mean WOMAC score at five years post-operatively was 25 (0 to 59), and at ten years was 27 (2 to 70). No femoral components were radiologically loose, although five had osteolysis in Gruen zone 1, three had osteolysis in zone 7, and two showed osteolysis in both zones 1 and 7. No osteolysis was observed around or distal to the prosthetic sleeve. No femoral components were revised, although three hips underwent an acetabular revision and two required a liner exchange. At a mean of ten years’ follow-up the S-ROM femoral component implanted for an anatomically difficult primary THR has excellent clinical and radiological results.
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.CLINBIOMECH.2005.12.012
Abstract: An in vitro cyclical testing simulating a passive mobilisation protocol was used to compare repair of flexor digitorum profundus tendon with modified-Bunnell two-strand pullout technique using a monofilament (Prolene), braided polyester (Ethibond) and a synthetic polyfilament ensheathed by caprolactan (Supramid) sutures. Eighteen fresh-frozen cadaveric fingers were randomly ided into three repair groups (n = 6) modified-Bunnell technique with 3/0 Prolene, Ethibond or Supramid. After repair, specimens were cyclically loaded from 2 to 15N at 5N/s, for a total of 500 cycles. Gap formation at the tendon-bone interface was assessed every 100 cycles. S les were tested to failure at the completion of 500 cycles. All sutures held in all specimens during cyclic testing. The gap formation after 500 cycles was greatest with Prolene suture (6.8 mm, SD 1.2) followed by Supramid suture (4.0 mm, SD 1.1) and Ethibond suture (1.7 mm, SD 1.7) (P < 0.05). Repairs with Supramid displayed higher failure load (52.7 N, SD 5.5) as compared to Prolene (37.6N, SD 4.7) (P = 0.001) but not compared to Ethibond (44.9 N, SD 7.1). The failure loads between Prolene and Ethibond did not differ (P = 0.130). Gap formation with Ethibond was significantly lower compared to Supramid and Prolene. The four strand nature of the Supramid repair was superior to Prolene but did not differ compared to Ethibond with respect to failure load. Prolene is the least favourable suture when considering gap formation and failure load, while Ethibond is the most favourable.
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.ARTH.2013.10.003
Abstract: Modification of titanium oxide by multiphase anodic spark deposition (ASD) has the potential to increase bioactivity and hasten osseointegration and biological fixation in uncemented arthroplasty. This study assessed the in vivo performance of control (Ti), plasma-sprayed HA-coated (TiHA) and ASD (Biospark) treated (TiAn) porous titanium implants with a solid core using a standard uncemented implant fixation sheep model. Cortical interfacial shear-strength and bone ingrowth in cortical and cancellous sites were quantified following 12 weeks in situ. Ultimate shear-strength for the Ti, TiHA and TiAn coatings was 33±9.5, 35.4±8.4 and 33.8±7.8 MPa, respectively, which was limited by coating delamination. ASD treatment was associated with significantly higher mean bone ingrowth at both sites. These results support the osteoconductive potential of the BioSpark treatment of porous titanium.
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.ARTHRO.2006.08.023
Abstract: Bone morphogenetic proteins (BMPs) are being developed to improve tendon-bone healing. To do this, it is essential to understand the endogenous expression of BMPs and their downstream signal transduction factors, Smads, during tendon-bone healing. An extra-articular patellar tendon-bone healing ovine model was set up, and histologic evaluation of the healing progress at the tendon-bone interface at 1, 2, 3, and 6 weeks was performed. Immunohistochemical staining of BMP-2, BMP-7, Smad1, Smad4, and Smad5 was carried out in all sections. The model revealed formation of a loose granuloma tissue layer between the tendon and bone at 1 week, remodeling starting at 2 weeks, and Sharpey-like collagen fiber formation at 3 and 6 weeks. All detected factors were elevated at the tendon-bone interface during healing, and the expression peaked at 2 to 3 weeks. The cells involved were osteoblastic-like cells, osteoclastic-like cells, mesenchymal cells, and fibroblasts. BMP-7 staining was mainly at the interface close to the bony side, whereas BMP-2 expression shifted to the tendon side at 6 weeks. The expression pattern of Smad1 and Smad5 was similar to that of BMP-7. Smad1 was also found to be expressed in osteoclastic-like cells at 1 and 2 weeks. Smad4 expression was the highest among all of the factors at all time points. The data suggest that endogenous BMP-2 and BMP-7 participate in tendon-bone healing and their functions involve their downstream signal transduction mediators, Smad1, Smad4, and Smad5. The temporal expression of BMPs should be considered when setting up therapeutic strategies using BMPs.
Publisher: Elsevier BV
Date: 03-2003
DOI: 10.1067/MSE.2003.24
Publisher: SAGE Publications
Date: 02-02-2016
Abstract: Purpose: To evaluate and characterize debris retrieved from the cerebral embolic protection devices (EPDs) used during carotid artery stenting (CAS) and compare debris size, volume, tissue types, cellular composition, and protein biomarker expression in symptomatic and asymptomatic patients. Methods: Distal protection filters were retrieved from 22 consecutive patients (mean age 71.6 years, range 52–85 16 men) undergoing elective CAS between July 2012 and February 2014 for % internal carotid artery stenosis (mean 85.4%±10.3%). Six patients were symptomatic. The debris within each EPD was visually characterized using stereomicroscopy and then processed for histology and immunohistochemistry. Biomarkers were immunohistochemically measured to evaluate plaque stability [matrix metalloproteinase-9 (MMP-9)], inflammation [glycoprotein CD68 and interleukin-6 (IL-6)], or phenotype [smooth muscle (SM)-actin and type IV collagen]. The immunohistochemical results were measured using semiquantitative grading criteria based on both staining intensity and distribution in the s les. Results: Macroscopic debris was visible in 5/22 EPDs 3 of the 5 filters came from symptomatic patients. Microscopic debris was detected in all filters and ranged in size from 0.01 to 8.57 mm 2 . Debris consisted of calcified, fibrous, and necrotic tissue, as well as fibrin and foam cells with no significant difference between the symptomatic and asymptomatic groups. There was no association between the degree or type of embolic material and stenosis severity, carotid tortuosity, calcium grade, soft plaque, or arch type. Symptomatic patients had a larger volume of debris (8.24 vs 0.58 mm 3 , p .01), mean particle size (1.30 vs 0.32 mm 2 , p .001), and expression of biomarkers IL-6 (2.17 vs 0.81, p .05), CD68 (2.00 vs 0.38, p .01), SM-actin (1.00 vs 0.25, p=0.055), type IV collagen (1.17 vs 0.25,p=0.082), and MMP-9 (1.00 vs 0.06, p .05). Conclusion: Histological analysis revealed particulate embolization in all EPDs used during CAS. Symptomatic patients had a larger volume of embolic debris, mean particle size, and the biomarkers associated with inflammation, necrotic core, and diminished fibrous cap.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2006
Publisher: Wiley
Date: 11-05-2005
DOI: 10.1002/JBM.B.30256
Abstract: Uncemented joint replacement with a variety of substrate materials, structures, and coatings are commonplace in arthroplasty. Even with specialized surgical preparation of bone, intimate contact between the implant and host bone may not always be achieved. This study evaluated the in vivo effect of fibrillar atelopeptide and PEG crosslinked collagens coatings placed directly into porous sintered bead structures on bone ingrowth using a skeletally mature bicortical, bilateral ovine tibia model. Bone ingrowth into the implants increased with time, although differences were not significant. At 4 weeks woven bone was present within the pores that remodeled with time. Significantly lower levels of ingrowth were observed in the intramedullary region of the implants when compared with the cortical region. Implant metal type did not affect ingrowth in both regions analyzed. Both fibrillar and crosslinked forms of dermal type I collagen did not significantly alter bone ingrowth.
Publisher: Elsevier BV
Date: 06-2002
Abstract: Knee kinematics after total knee arthroplasty is dictated primarily by implant geometry and native soft tissue constraints. This study highlights the importance of a functioning posterior cruciate ligament in limiting excessive anteroposterior translation in a mobile bearing knee design that relies on native posterior cruciate ligament integrity and postarthroplasty tensioning for stability rather than any inherent mechanical design stability, such as anterior rails or stops.
Publisher: SAGE Publications
Date: 06-2006
DOI: 10.1016/J.JHSB.2005.12.004
Abstract: Flexor digitorum profundus (FDP) tendon avulsions, although uncommon, are not infrequent injuries. A widely accepted method of treating Type 1 FDP avulsions is a pullout suture tied over a button on the nail plate. The external dorsal button is often a source of inconvenience for the patient. Potential risks associated with button use include nail plate deformities, nail fold necrosis and infections tracking along the sutures. The use of small suture anchors provides a satisfactory alternative, because buried fixation avoids these potential complications. This in vitro, biomechanical study examined the influence of the anchor orientation on the properties of the repaired FDP tendon using human cadavers.
Publisher: Elsevier BV
Date: 11-2001
Abstract: The coracoclavicular ligaments vary widely in morphology and anatomic descriptions. Few authors have adequately described the coracoclavicular ligaments' anatomy, and a number of discrepancies exist in the anatomy literature. This study examines the complex anatomy of the coracoclavicular ligaments and their relationships to clinically important bony landmarks. The geometric dimensions of 24 coracoclavicular ligament specimens from fresh human cadaveric shoulders were examined and quantified with 13 different measurements. Particular attention was given to any inter-specimen anatomic variance. The coracoid insertions of the conoid ligaments displayed high variance, with 33% (8/24) being confluent with the lateral fibers of the superior transverse scapular ligament. A further 15% (3/24) presented an additional lateral fascicle. The distance from the lateral trapezoid ligament to the distal clavicle averaged 15.3 mm. Three distinct and previously unreported conoid ligament variants lend themselves to an anatomic classification (types I, II, and III). A safety margin of 15 mm is suggested for distal clavicle resection in incomplete acromioclavicular joint injuries to preserve the intact coracoclavicular ligament.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
DOI: 10.1097/BSD.0B013E31826851A4
Abstract: Comparative evaluation of in vitro and in vivo biomechanics, resulting fusion and histomorphometric aspects of polyetheretherketone (PEEK) versus titanium (Ti) interbody fusion devices in an animal model with similar volumes of bone graft. Identify differences in the characteristics of fusion and biomechanics immediately following implantation (time 0) and at 26 weeks with each interbody implant. PEEK has been well accepted in spinal surgery, it provides a closer match to the mechanical properties of bone than metallic implants such as Ti. This is thought to reduce graft stress shielding and subsidence of interbody fusion devices. There remains controversy as to the overall influence of this as a factor influencing resultant fusion and initial stability. Although material modulus is 1 factor of importance, other design factors are likely to play a large role determining overall performance of an interbody implant. A Ti and PEEK device of similar size with a central void to accommodate graft material were compared. The PEEK device had a ridged surface on the caudal and cephalad surfaces, whereas Ti device allowed axial compliance and had bone ingrowth endplates and polished internal surfaces. A 2-level ALIF was performed in 9 sheep and fusion, biomechanics, and bone apposition were evaluated at 26 weeks. Time 0 in vitro biomechanical tests were performed to establish initial stability immediately after implantation. No differences were detected in the biomechanical measures of each of the devices in in vitro time 0 tests. All levels were fused by 26 weeks with considerably lower range of motion when compared with in vitro tests. Range of motion in all modes of bending was reduced by over 70% when compared with intact values for axial rotation (Ti-74%, PEEK-71%), lateral bending (Ti-90%, PEEK-88%), and flexion/extension (Ti-92%, PEEK-91%). Mechanical properties of fusions formed with each implant did not differ however, bone apposition was variable with polished internal Ti surfaces being lower than PEEK and treated Ti endplates showing the greatest levels. Graft material displayed axial trabecular alignment with both implants. Although material properties and surface characteristics resulted in differing amounts of biological integration from the host, both implants were capable of producing excellent fusion results using similar volumes of bone graft.
Publisher: IEEE
Date: 03-2009
Publisher: Wiley
Date: 02-2016
DOI: 10.1111/OS.12221
Publisher: Georg Thieme Verlag KG
Date: 02-05-2023
DOI: 10.1055/S-0043-57221
Abstract: Objective The aim of this study was to compare the interfragmentary compressive force and area of compression generated by cortical screws inserted as either a lag screw or position screw in simulated lateral humeral condylar fractures. Study Design Ex vivo biomechanical study. Materials and Methods Thirteen pairs of cadaveric humeri from skeletally mature Merinos with simulated lateral humeral condylar fractures were used. Pressure sensitive film was inserted into the interfragmentary interface prior to fracture reduction with fragment forceps. A cortical screw was inserted as a lag screw or a position screw and tightened to 1.8Nm. Interfragmentary compression and area of compression were quantified and compared between the two treatments groups at three time points. Results After fracture reduction using fragment forceps (Time point 1: T1), there was no significant difference in interfragmentary compression and area of compression between the two treatments. A combination of fragment forceps and a cortical screw inserted as a lag screw (Time point 2: T2) produced significantly greater interfragmentary compression and area of compression compared with the same screw inserted as a positional screw. After removal of the fragment forceps, leaving only the cortical screw (Time point 3: T3), both the interfragmentary compression and area of compression remain significantly greater in the lag screw group. Conclusion Lag screws generate a greater force of compression and area of compression compared with position screws in this mature ovine humeral condylar fracture model.
Publisher: Springer Science and Business Media LLC
Date: 15-12-2017
DOI: 10.1007/S00586-015-4353-8
Abstract: The primary objective of this paper was to provide a systematic review of the available clinical studies of Ti/PEEK combined cages in spinal interbody fusion surgeries, focusing on their radiological and clinical outcomes. A secondary aim was to provide a review and evaluation of the in vitro and preclinical studies reported on Ti/PEEK-coated implants. A systematic search of the literature was performed in March 2015 via three databases: Medline, Embase and Cochrane library. The following key search terms were combined with synonyms to identify relevant articles: "spinal fusion," "PEEK," "titanium" and "cage." The novelty of this intervention translates into a paucity of clinical trials, albeit the results of the seven clinical studies that met the criteria for inclusion are promising. All studies reported rate of fusion as a primary outcome. Two studies reported slightly improved fusion in the experimental Ti/PEEK combination cohort, one study identical fusion (91.7 %) and three studies excellent fusion (96, 100 and 94 %) in the Ti/PEEK cohort, although no differences reached statistical significance. Clinical studies at this early stage demonstrate that Ti/PEEK implants are safe and efficacious, exhibiting similar fusion rates and clinical outcomes compared to the current standard PEEK. There is clinical evidence substantiating the improved radiographic fusion of Ti/PEEK, albeit the differences were not significant. This field is promising, gaining substantial popularity, and further clinical trials are needed in the future to establish Ti/PEEK cages as a mainstay of clinical practice.
Publisher: Wiley
Date: 28-10-2013
DOI: 10.1111/ANS.12428
Abstract: In order to emulate normal knee kinematics more closely, and thereby potentially improve wear characteristics and implant longevity, the medial pivot-type knee replacement geometry was designed. In the current study the outcome of 50 consecutive knee replacements using a medial pivot-type knee replacement was compared with the results in the Australian Orthopaedic Association National Joint Replacement Registry. Pre- and post-operatively at follow-up evaluation consisted of the Knee Society score system and the Western Ontario and McMaster Universities Arthritis Index Score. Patient satisfaction was documented using 5-point Likert-type scales. Standard radiographs were used to assess signs of radiographic failure. Revisions were subcategorized into major total, major partial and minor. Patient records were cross-referenced against the Australian Orthopaedic Associations National Joint Replacement Registry's and the outcome compared with the registry's subset of data on the medial pivot knee used. According to the patients' Knee Society score system and Western Ontario and McMaster Universities Arthritis Index scores, there was good pain relief and functional improvement none of the implants showed radiographic signs of failure. There was one minor revision. There was no statistically significant difference in revision rate compared with the registry results. The medial pivot knee-type implant in this series provided pain relief, functional improvement and a revision rate, similar to what is reported in the literature after a longer follow-up period, which is reassuring for those who use this type of implant on a day-to-day basis.
Publisher: MyJove Corporation
Date: 04-09-2016
DOI: 10.3791/54351
Publisher: Springer Science and Business Media LLC
Date: 04-2011
Publisher: IEEE
Date: 11-2011
Publisher: Elsevier BV
Date: 2004
Publisher: Springer Science and Business Media LLC
Date: 06-04-2013
DOI: 10.1007/S00198-013-2345-2
Abstract: Fractures in post-menopausal osteoporosis cause significant morbidity however, animal models for post-menopausal fracture healing lack the effect of ageing. Therefore, we developed a model using aged animals with chronic oestrogen deficiency, which demonstrates inferior fracture repair (decreased healing histologically, bone mineral density and content and strength). This novel model may help develop molecular strategies for osteoporotic fracture repair. The femur is susceptible to damage by both systemic conditions such as osteoporosis and locally by traumatic injury. The capacity for fracture repair decreases with age, while the risk of fracture increases. As studies of osteoporotic fracture healing in rats traditionally use a period of 3 months or less of oestrogen deficiency prior to fracturing, we aimed to establish a osteoporosis model in rats with chronic oestrogen deficiency by 12 months to better mimic human female osteoporosis. Seventy female Sprague-Dawley rats (10 weeks old) were ovariectomised or sham operated and housed for 12 months. The right femur was fractured by way of an open osteotomy and fixed with an intramedullary Kirschner wire. Animals were sacrificed at 1, 3 and 6 weeks for radiography, dual-energy X-ray absorptiometry, tensile testing and histology. Bone mineral density and bone mineral content were lower by 60 and 63 %, respectively, (p < 0.05) in the bilaterally ovariectomized (OVX) groups than those in the sham groups at 6 weeks in the right fractured femurs. Maximum breaking force of the OVX group was lower than that of the sham group, with the greatest difference seen at 6 weeks following osteotomy. Histologically, the OVX groups demonstrated a delay in cellular differentiation within the fracture callus and the presence of bone resorption. The sham animals had a superior histological healing pattern with an Allen score of 4 at 6 weeks compared to a score of 1 for the OVX groups (p < 0.01). Long-term ovariectomy has a deleterious effect on fracture healing in a rodent model.
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.ARTH.2011.01.013
Abstract: Cement within cement revisions provide substantial benefits for conventional revision yet remains uncommon possibly because of the perceived weakness of the cement-cement interface. This study investigated the flexural strength of beams composed of 2 different cements, exploring the factors of pore size, fracture location, viscosity, and the surface roughness of the interface. We found no significant difference when comparing combinations of different cements (P = .30), varying pore sizes (P = .13), or surface roughness (P = .39). Differences in fracture locations and viscosity combinations approached statistical significance (P = .08 and .05, respectively). Our findings suggest strong bonding between cements at the interface, with other factors being more important causes of weakness. Thus, we recommend that the strength of the cement-cement interface should not be a factor when considering such revisions.
Publisher: Springer Berlin Heidelberg
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 13-08-2021
DOI: 10.1186/S13018-021-02651-8
Abstract: Calcium phosphate-based bone graft substitutes are used to facilitate healing in bony defects caused by trauma or created during surgery. Here, we present an injectable calcium phosphate-based bone void filler that has been purposefully formulated with hyaluronic acid to offer a longer working time for ease of injection into bony defects that are difficult to access during minimally invasive surgery. The bone substitute material deliverability and physical properties were characterized, and in vivo response was evaluated in a critical size distal femur defect in skeletally mature rabbits to 26 weeks. The interface with the host bone, implant degradation, and resorption were assessed with time. The calcium phosphate bone substitute material could be injected as a paste within the working time window of 7–18 min, and then self-cured at body temperature within 10 min. The material reached a maximum ultimate compressive strength of 8.20 ± 0.95 MPa, similar to trabecular bone. The material was found to be biocompatible and osteoconductive in vivo out to 26 weeks, with new bone formation and normal bone architecture observed at 6 weeks, as demonstrated by histological evaluation, microcomputed tomography, and radiographic evaluation. These findings show that the material properties and performance are well suited for minimally invasive percutaneous delivery applications.
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.JHSA.2010.02.005
Abstract: Flexor tendons should be repaired with suture material strong enough to permit early motion and small enough for the resulting knot to allow unimpeded tendon glide and healing. This study sought to define differences in cross-sectional area and knotted tensile strength among Fiberwire, Prolene, and Ticron sutures. Five strands, each of 3-0 and 4-0 Prolene, Ticron, and Fiberwire sutures, were embedded in polymethylmethacrylate and sectioned in a linear precision saw to obtain 10 cross-sections of each material and size. These were examined by scanning electron microscopy and digitally analyzed for cross-sectional areas. Ten strands of each suture material and size had a single throw knot placed, and they were loaded to failure in a micromechanical tester. Prolene and Ticron cross-sections were circular. Fiberwire was noncircular. The 3-0 Fiberwire sutures had greater cross-sectional area than the 3-0 Ticron sutures (p < .001), which in turn were larger than 3-0 Prolene (p < .05). The 4-0 Fiberwire cross-sectional area was also greater than that of 3-0 Ticron and Prolene (p < .05). After relating knotted tensile strength to cross-sectional area, Fiberwire was 10% stronger than Prolene, and 25% stronger than Ticron. Fiberwire is not only stronger, but also larger than other sutures in the same or even higher suture size category. Failure to meet the United States Pharmacopeia standards for suture diameter is declared in the product information sheet, although surgeons may not be aware of these size variations. Suture size definitions are currently based on diameter, a consistent measure for circular monofilament sutures, but not for braided or noncircular sutures.
Publisher: SAGE Publications
Date: 29-01-2010
Publisher: Spandidos Publications
Date: 05-2011
DOI: 10.3892/IJO.2011.970
Abstract: In the last decade, microRNAs (miRNAs small noncoding RNA molecules) as post-transcriptional regulators have been a hotspot in research for their involvement in biological processes and tumour development. However, there have been few reviews focusing on a single miRNA family. The dysregulation of miRNAs appears to play a crucial role in cancer pathogenesis where they exert their effect as oncogenes or as tumour suppressors. This review summarises current studies on the dysregulation of the microRNA-34 (miR-34) family in different types of cancers and its role in the p53 network. The structure of the miR-34 family members includes p53-binding sites reflecting their function as tumour suppressors downstream of the p53 pathway. miR-34 dysregulation occurs in cancers, including several epithelial cancers, melanomas, neuroblastomas, leukemias and sarcomas, in the presence or absence of the p53 mutation. For these cancers, functional restoration of miR-34 is a useful novel therapy. As evidenced from preclinical and clinical studies, the miR-34 family plays an important role in the treatment of miR-34-dysregulated cancers with mutant or wild-type p53. This review will have a potential impact in the clinical treatment of p53-mutant and/or miR-34-dysregulated cancers using a miR-34 restoration approach.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.RVSC.2015.04.006
Abstract: Fentanyl delivered via a transdermal patch has the potential to decrease the need for post-operative handling of sheep undergoing surgical procedures. Two studies were performed to test: (1) the ideal timing for the application of pre-emptive analgesic patches and (2) the efficacy of a 2 µg/kg/h dose, as extrapolated from other species. The first study had sheep ided into two groups. Group 1 had a fentanyl patch applied for 24 h prior to a patch change and group 2 had a fentanyl patch applied 72 h prior to a change. The second study applied the results obtained in the first and tested the efficacy of 2 µg/kg/h as an effective dose in an orthopaedic surgical environment. Results indicated that the ideal time for pre-emptive fentanyl patch administration is 24-36 h prior to surgery and that 2 µg/kg/h is an effective minimum therapeutic dose rate for the use of fentanyl as an analgesic in an orthopaedic surgical environment.
Publisher: Wiley
Date: 26-10-2011
DOI: 10.1002/JOR.21277
Abstract: Harvest of the central one-third of the patella tendon (PT) is routinely performed for anterior cruciate ligament reconstruction (ACLR). Patella infera may ensue. In this study we unilaterally resected the central one-third of the PT in 20 sheep, without reconstructing or defunctionalizing the native ACL, and examined the effects at 3, 6, 12, and 24 weeks postoperatively on PT length, histological appearance of the donor defect and in vitro stifle joint kinematics. Mean length increases (p > 0.263) in the operated tendons of 0.3%, 2.8%, 0.5%, and 2.4% were observed at 3, 6, 12, and 24 weeks. A significant proximal shift of the patella correlated well with a mean 2.35° retardation of patellar flexion (r = 0.440, p = 0.001). A mean net 4.9° decrease in medial patellar tilt was also observed (p < 0.001), but was not coupled with changes in tibial rotation. Donor defect tissue showed a distinct progression of healing with time, remodeling from dense scar tissue at 3 weeks to bundles of well-organized collagen enveloped by vascularized loose connective tissue at 24 weeks but was not associated with the restoration of kinematics. These results suggest that resection of the central one-third of the PT and leaving the defect open in the ovine stifle joint may be associated with increased PT length and changes in patellar kinematics which do not recover 6 months postoperatively. The lack of patella infera may render this animal model unsuitable for the interpretation of joint kinematics following PT resection for human ACLR.
Publisher: SAGE Publications
Date: 14-09-2012
Abstract: Techniques to improve and accelerate tendon-bone healing could be advantageous in anterior cruciate ligament (ACL) reconstruction. Effects of demineralized bone matrix (DBM) on intra-articular tendon-bone healing have not been examined. Demineralized bone matrix has the potential to convey osteoinductive growth proteins to the site of healing at the tendon-bone interface. We hypothesized that the presence of DBM will result in more bone formation and hasten tendon-bone healing. Controlled laboratory study. Fifty-six female athymic rnu/rnu (nude) rats were used. Rats were randomly allocated into 2 groups (control or treatment). The control group underwent an ACL reconstruction, while the treatment group had human DBM implanted in the tendon graft and bone tunnel before reconstruction. Rats were sacrificed at 2 (n = 8), 4 (n = 24), and 6 (n = 24) weeks for histological, and immunohistochemical (t = 2, 4, and 6 weeks), and biomechanical testing and micro–computed tomography (t = 4 and 6 weeks) end points. Our findings suggest that in the presence of DBM, tendon-bone healing is augmented by increased woven bone formation and enhanced bone remodeling as indicated by histology and micro–computed tomography. This ultimately resulted in a statistically significant increase in peak load to failure of the tendon-bone interface at 4 weeks (DBM group: 5.96 ± 1.36 N control group: 2.86 ± 0.7 N) and 6 weeks (DBM group: 9.13 ± 0.97 N control group: 5.81 ± 1.1 N). Demineralized bone matrix at the tendon-bone interface promotes healing between the tendon and bone in a rodent ACL model. Introduction of osteoinductive DBM at the tendon-bone interface during ACL reconstructive surgery may improve short-term outcomes.
Publisher: Georg Thieme Verlag KG
Date: 2011
Abstract: Objectives: The bone-patellar tendon-bone complex is routinely harvested for anterior cruciate ligament reconstruction in humans. Patella infera may ensue. However, the contribution from resection of the central one-third of the patellar tendon (PT) to potentially altered patellofemoral kinematics, in addition to those induced by a positional shift of the patella, are yet to be distinguished. Objectives of this study were to characterize changes in intraoperative patellar kinematics and PT length in nine sheep immediately following unilateral resection of the central one-third PT, and again at six, 12 and 24 weeks postoperatively. Methods: Following implantation of bone-screws into the patella and tibia, electromagnetic receivers were anchored to these, and then passively-induced, unloaded patellar kinematics were captured. Patellar kinematics were referenced to the tibial coordinate frame and analysed using non-parametric tests (Wilcoxon Signed Rank Test). Results: Resection alone did cause significant alteration in kinematics at the time of surgery (p .05). Postoperatively, a mean increase in PT length of 2.6 mm was detected in the operated stifles, reflected partly as a net 2.8 mm proximal patellar shift (p .001). This was accompanied by a mean net six degree medial shift in the patellar tilt pattern (p .001). Significant changes to patellar spin in the latter parts of flexion were also observed (p .005). Kinematic and length changes did not recover up to 24 weeks postoperatively. Clinical significance: The data obtained in this study suggests that both the patellar height and integrity of the PT are important determinants of patellar kinematics in the ovine stifle joint.
Publisher: Elsevier BV
Date: 09-2011
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.1016/J.BONE.2006.05.011
Abstract: The epidemiology and trends in wrist fracture admissions to public and private acute hospitals in New South Wales (NSW), Australia, between July 1993 and June 2003 were examined using routinely collected hospital separations statistics. During the study period, the number of hospital separations for wrist fractures increased by 71% in men, an average yearly increase of 6.5%, and by 43% in women, an average yearly increase of 3.9%. A modest, but significant, increase in age-specific and age-standardised hospitalisation rates for wrist fractures was also observed. Whilst the majority of wrist fractures were due to falls, the proportion of falls-related wrist fractures decreased significantly over time. This decrease was more pronounced in males and was accompanied by a rise in the proportion of wrist fractures resulting from high energy mechanisms such as transport, violence and machinery-related incidents. The difference in hospitalised wrist fracture rates between men and women could not be explained solely on the basis of the role played by osteoporosis, indicating the need for more research to improve our understanding of the underlying factors of this type of fracture in older people.
Publisher: Elsevier BV
Date: 05-2009
Publisher: International Society of Endovascular Specialists
Date: 15-02-2011
DOI: 10.1583/10-3266.1
Abstract: To present the early and midterm results of endovascular stent reconstruction of the occluded aortoiliac segment with selective use of the Outback LTD re-entry catheter. Between April 2004 and February 2010, 8 patients (5 women mean age 58.4 years, range 47-68) with occlusion of the infrarenal aorta extending to the common or external iliac arteries underwent endovascular reconstruction with double-barrel self-expanding stents. Indications for treatment were severe claudication in 6 and ulceration in 2 patients. The technical success rate was 100%, facilitated by the use of the Outback LTD catheter for accurate wire re-entry in 3 cases. There was no in-hospital mortality. One patient had a major complication (femoral artery dissection, brachial artery thrombosis, and retroperitoneal hematoma) unrelated to the re-entry device. Mean operating time was 137 minutes (range 70-253) and length of stay was 1.5 days (range 1-2). During a mean follow-up of 12.5 months (range 6-29), primary patency was 100% with no secondary interventions. Total endovascular reconstruction of the occluded infrarenal aorta that extends into the iliac arteries is durable at midterm follow-up. Adjunctive use of the Outback LTD re-entry catheter can facilitate technical success.
Location: United States of America
No related grants have been discovered for William Walsh.