ORCID Profile
0000-0001-9543-4108
Current Organisation
University of Southampton
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Publisher: Informa UK Limited
Date: 10-07-2018
Publisher: Elsevier BV
Date: 03-2020
Publisher: Springer Science and Business Media LLC
Date: 31-01-2022
DOI: 10.1007/S10439-022-02921-4
Abstract: Biomechanical changes after anterior cruciate ligament reconstruction (ACLR) may be detrimental to long-term knee-joint health. We used pattern recognition to characterise biomechanical differences during the landing phase of a single-leg forward hop after ACLR. Experimental data from 66 in iduals 12-24 months post-ACLR (28.2 ± 6.3 years) and 32 controls (25.2 ± 4.8 years old) were input into a musculoskeletal modelling pipeline to calculate joint angles, joint moments and muscle forces. These waveforms were transformed into principal components (features), and input into a pattern recognition pipeline, which found 10 main distinguishing features (and 8 associated features) between ACLR and control landing biomechanics at significance $$\\alpha =0.05$$ α = 0.05 . Our process identified known biomechanical characteristics post-ACLR: smaller knee flexion angle less knee extensor moment lower vasti, rectus femoris and hamstrings forces. Importantly, we found more novel and less well-understood adaptations: smaller ankle plantar flexor moment lower soleus forces and altered patterns of knee rotation angle, hip rotator moment and knee abduction moment. Crucially, we identified, with high certainty, subtle aberrations indicating landing instability in the ACLR group for: knee flexion and internal rotation angles and moments hip rotation angles and moments and lumbar rotator and bending moments. Our findings may benefit rehabilitation and assessment for return-to-sport 12–24 months post-ACLR.
Publisher: BMJ
Date: 02-2023
DOI: 10.1136/BMJOPEN-2022-068040
Abstract: Running is one of the most popular recreational activities worldwide, due to its low cost and accessibility. However, little is known about the impact of running on knee joint health in runners with and without a history of knee surgery. The primary aim of this longitudinal cohort study is to compare knee joint structural features on MRI and knee symptoms at baseline and 4-year follow-up in runners with and without a history of knee surgery. Secondary aims are to explore the relationships between training load exposures (volume and/or intensity) and changes in knee joint structure and symptoms over 4 years explore the relationship between baseline running biomechanics, and changes in knee joint structure and symptoms over 4 years. In addition, we will explore whether additional variables confound, modify or mediate these associations, including sex, baseline lower-limb functional performance, knee muscle strength, psychological and sociodemographic factors. A convenience s le of at least 200 runners (sex/gender balanced) with (n=100) and without (n=100) a history of knee surgery will be recruited. Primary outcomes will be knee joint health (MRI) and knee symptoms (baseline 4 years). Exposure variables for secondary outcomes include training load exposure, obtained daily throughout the study from wearable devices and three-dimensional running biomechanics (baseline). Additional variables include lower limb functional performance, knee extensor and flexor muscle strength, biomarkers, psychological and sociodemographic factors (baseline). Knowledge and beliefs about osteoarthritis will be obtained through predefined questions and semi-structured interviews with a subset of participants. Multivariable logistic and linear regression models, adjusting for potential confounding factors, will explore changes in knee joint structural features and symptoms, and the influence of potential modifiers and mediators. Approved by the La Trobe University Ethics Committee (HEC-19524). Findings will be disseminated to stakeholders, peer-review journals and conferences.
Publisher: Wiley
Date: 30-04-2021
DOI: 10.1002/JOR.25053
Abstract: Altered biomechanics are frequently observed following anterior cruciate ligament reconstruction (ACLR). Yet, little is known about knee‐joint loading, particularly in the patellofemoral‐joint, despite patellofemoral‐joint osteoarthritis commonly occurring post‐ACLR. This study compared knee‐joint reaction forces and impulses during the landing phase of a single‐leg forward hop in the reconstructed knee of people 12‐24 months post‐ACLR and uninjured controls. Experimental marker data and ground forces for 66 participants with ACLR (28 ± 6 years, 78 ± 15 kg) and 33 uninjured controls (26 ± 5 years, 70 ± 12 kg) were input into scaled‐generic musculoskeletal models to calculate joint angles, joint moments, muscle forces, and the knee‐joint reaction forces and impulses. The ACLR group exhibited a lower peak knee flexion angle (mean difference: −6° 95% confidence interval: [−10°, −2°]), internal knee extension moment (−3.63 [−5.29, −1.97] percentage of body weight × participant height (body weight [BW] × HT), external knee adduction moment (‐1.36 [−2.16, −0.56]% BW × HT) and quadriceps force (−2.02 [−2.95, −1.09] BW). The ACLR group also exhibited a lower peak patellofemoral‐joint compressive force (−2.24 [−3.31, −1.18] BW), net tibiofemoral‐joint compressive force (−0.74 [−1.20, 0.28] BW), and medial compartment force (−0.76 [−1.08, −0.44] BW). Finally, only the impulse of the patellofemoral‐joint compressive force was lower in the ACLR group (−0.13 [−0.23, −0.03] body weight‐seconds). Lower compressive forces are evident in the patellofemoral‐ and tibiofemoral‐joints of ACLR knees compared to uninjured controls during a single‐leg forward hop‐landing task. Our findings may have implications for understanding the contributing factors for incidence and progression of knee osteoarthritis after ACLR surgery.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 20-02-2020
DOI: 10.1249/MSS.0000000000002297
Abstract: This study aimed to evaluate the differences in lower-limb biomechanics between adult subelite competitive football players with and without hip-related pain during two contrasting tasks—walking and single-leg drop jump (SLDJ)—and to determine whether potential differences, if present, are sex dependent. Eighty-eight football players with hip-related pain (23 women, 65 men) and 30 asymptomatic control football players (13 women, 17 men) who were currently participating in competitive sport were recruited. Biomechanical data were collected for the stance phase of walking and SLDJ. Pelvis, hip, knee, and ankle angles, as well as the impulse of the external joint moments, were calculated. Differences between groups and sex-specific effects were calculated using linear regression models. Compared with their asymptomatic counterparts, football players with hip-related pain displayed a lower average pelvic drop angle during walking ( P = 0.03) and a greater average pelvic hike angle during SLDJ ( P 0.05). Men with hip-related pain displayed a smaller total range of motion (excursion) for the transverse plane pelvis angle ( P = 0.03) and a smaller impulse of the hip external rotation moment ( P 0.01) during walking compared with asymptomatic men. Women with hip-related pain displayed a greater total range of motion (excursion) for the sagittal plane knee angle ( P = 0.01) during walking compared with asymptomatic women. Overall, few differences were observed in lower-limb biomechanics between football players with and without hip-related pain, irrespective of the task. This outcome suggests that, despite the presence of symptoms, impairments in lower-limb biomechanics during function do not appear to be a prominent feature of people with hip-related pain who are still participating in sport.
Publisher: SAGE Publications
Date: 06-05-2020
Abstract: Patellofemoral joint (PFJ) osteoarthritis may occur after anterior cruciate ligament reconstruction (ACLR). The mechanisms underpinning the development of PFJ osteoarthritis are not known but may relate to altered PFJ loading. Few studies have assessed PFJ loads during high-impact tasks, such as running, beyond the acute rehabilitation phase (ie, months) after ACLR. The purpose was to compare between-limb joint angles, joint moments, and PFJ contact force during running in in iduals at 12 to 24 months after unilateral ACLR. We hypothesized that peak knee flexion angle, knee extension moment, and PFJ contact force during stance would be lower in the ACLR limb compared with the uninjured limb. Controlled laboratory study. A total of 55 participants (mean ± SD age, 28 ± 7 years), 12 to 24 months after ACLR, ran at a self-selected speed (2.9 ± 0.3 m/s). Measured kinematics and ground-reaction forces were input into musculoskeletal models to calculate joint moments and muscle forces. These values were subsequently input into a PFJ model to calculate contact force peak and impulse. Outcome measures were compared between the ACLR and uninjured limbs. In the ACLR limb, compared with the uninjured limb, the PFJ contact force displayed a lower peak (ACLR, 6.1 ± 1.3 body weight [BW] uninjured, 6.7 ± 1.4 BW P .001) and impulse (ACLR, 0.72 ± 0.17 BW*seconds [BWs] uninjured, 0.81 ± 0.17 BWs P .001). At the time of the peak PFJ contact force, the knee extension moment was lower in the ACLR limb (ACLR, 14.0 ± 2.4 %BW*height [%BW*HT] uninjured, 15.5 ± 2.5 %BW*HT P .001). The opposite was true for the ankle plantarflexion moment (ACLR, 12.1 ± 2.6 %BW*HT uninjured, 11.5 ± 2.7 %BW*HT P = .019) and the hip extension moment (ACLR, 2.3 ± 2.5 %BW*HT uninjured, 1.6 ± 2.3 %BW*HT P = .013). The foot-ground center of pressure was located more anteriorly with respect to the ankle joint center (ACLR, 5.8 ± 0.9 %height [%HT] uninjured, 5.4 ± 1.0 %HT P = .001). No differences were found for the sagittal plane hip, knee, and ankle angles. The ACLR limb experienced lower peak PFJ loads during running, explained by a small anterior shift in the foot-ground center of pressure during stance that offloaded the torque demand away from the ACLR knee. Lower net PFJ loading during running in the ACLR limb more than 12 months after ACLR suggests that underloading might play a role in the onset of PFJ osteoarthritis after ACLR.
Publisher: Wiley
Date: 18-10-2023
DOI: 10.1111/JBI.14744
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.CLINBIOMECH.2019.06.001
Abstract: The effect of pain on lower limb biomechanics during walking has been found to be sex specific for certain joint diseases. However, it is not known if sex is an effect-modifier in people with hip pain. Therefore, the aim of the study was to determine the differences in lower limb biomechanics between men and women with hip-related groin pain during functional tasks. 65 male and 23 female football players with hip-related groin pain were recruited. Biomechanical data were recorded during walking and the single-leg drop jump. Hip, knee and ankle joint kinematics and kinetics were calculated. Differences between men and women were assessed using statistical parametric mapping. Walking: Men with hip-related groin pain walked with lower hip flexion and internal rotation angles during stance compared to women. During different sections of stance, men also displayed a lower hip adduction angle and 'external' adduction moment, a lower knee flexion angle and 'external' flexion moment, as well as greater 'external' dorsi-flexion moment and impulse. Single-leg drop jump: Men with hip-related groin pain displayed a lower hip flexion angle during early stance, and greater 'external' knee flexion and ankle dorsi-flexion moments. The impulse of the 'external' dorsi-flexion moment was also greater for men compared to women. Men and women with hip-related groin pain display differing lower limb biomechanics in both low and high impact tasks. Sex may therefore be a potential effect modifier in people with hip-related groin pain. Future research in this area should incorporate sex-specific analyses. NA.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Springer Science and Business Media LLC
Date: 06-02-2018
DOI: 10.1038/S41598-017-19098-9
Abstract: Anterior cruciate ligament (ACL) injuries are a burdensome condition due to potential surgical requirements and increased risk of long term debilitation. Previous studies indicate that muscle forces play an important role in the development of ligamentous loading, yet these studies have typically used cadaveric models considering only the knee-spanning quadriceps, hamstrings and gastrocnemius muscle groups. Using a musculoskeletal modelling approach, we investigated how lower-limb muscles produce and oppose key tibiofemoral reaction forces and moments during the weight acceptance phase of unanticipated sidestep cutting. Muscles capable of opposing (or controlling the magnitude of) the anterior shear force and the external valgus moment at the knee are thought to be have the greatest potential for protecting the anterior cruciate ligament from injury. We found the best muscles for generating posterior shear to be the soleus, biceps femoris long head and medial hamstrings, providing up to 173N, 111N and 77N of force directly opposing the anterior shear force. The valgus moment was primarily opposed by the gluteus medius, gluteus maximus and piriformis, with these muscles providing contributions of up to 32 Nm, 19 Nm and 21 Nm towards a knee varus moment, respectively. Our findings highlight key muscle targets for ACL preventative and rehabilitative interventions.
Publisher: Wiley
Date: 04-05-2016
DOI: 10.1002/JOR.23264
Abstract: This study quantified the contributions by muscles, gravity, and inertia to the tibiofemoral compartment forces in the symptomatic (SYM) and asymptomatic (ASYM) limbs of varus mal-aligned medial knee osteoarthritis (OA) patients, and compared the results with healthy controls (CON). Muscle forces and tibiofemoral compartment loads were calculated using gait data from 39 OA patients and 15 controls aged 49 ± 7 years. Patients exhibited lower knee flexion angle, higher hip abduction, and knee adduction angles, lower internal knee flexion torque but higher external knee adduction moment. Muscle forces were highest in CON except hamstrings, which was highest in SYM. ASYM muscle forces were lowest for biceps femoris short head and gastrocnemius but otherwise intermediate between SYM and CON. In all subjects, vasti, hamstrings, gastrocnemius, soleus, gluteus medius, gluteus maximus, and gravity were the largest contributors to medial compartment force (MCF). Inertial contributions were negligible. Highest MCF was found in SYM throughout stance. Small increases in contributions from hamstrings, gluteus maximus, gastrocnemius, and gravity at the first peak soleus and rectus femoris at the second peak and soleus, gluteus maximus, gluteus medius, and gravity during mid-stance summed to produce significantly higher total MCF. Compared to CON, the ASYM limb exhibited similar peak MCF but higher mid-stance MCF. In patients, diminished non-knee-spanning muscle forces did not produce correspondingly diminished MCF contributions due to the influence of mal-alignment. Our findings emphasize consideration of muscle function, lower-limb alignment, and mid-stance loads in developing interventions for OA, and inclusion of the asymptomatic limb in clinical assessments. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:321-330, 2017.
Publisher: Wiley
Date: 23-03-2018
DOI: 10.1002/JOR.23883
Abstract: This study quantified the contributions by muscular, gravitational and inertial forces to the ground reaction force (GRF) and external knee adduction moment (EKAM) for knee osteoarthritis (OA) patients and controls walking at similar speeds. Gait data for 39 varus mal-aligned medial knee OA patients and 15 controls were input into musculoskeletal models to calculate the contributions of in idual muscles and gravity to the fore-aft (progression), vertical (support), and mediolateral (balance) GRF, and the EKAM. The temporal patterns of contributions to GRF and EKAM were similar between the groups. Magnitude differences in GRF contributions were small but some reached significance. Peak GRF contributions were lower in patients except hamstrings in early-stance progression (p < 0.001) and gastrocnemius in late-stance progression (p < 0.001). Both EKAM peaks were higher in patients, due mainly to greater adduction contribution from gravity (p < 0.001) at the first peak, and lower abduction contributions from soleus (p < 0.001) and gastrocnemius (p < 0.001) at the second peak. Gluteus medius contributed most to EKAM in both groups, but was higher in patients during mid-stance only (p < 0.001). Differences in GRF contributions were attributed to altered quadriceps-hamstrings action as well as compensatory adaptation of the ankle plantarflexors to reduced gluteus medius action. The large effect of varus mal-alignment on the frontal-plane moment arms of the gravity, soleus, and gastrocnemius GRF contributions about the knee explained greater patient EKAM. Our results shed further light on how the EKAM contributes to altered knee-joint loads in OA and why some interventions may affect different portions of the EKAM waveform. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Publisher: Human Kinetics
Date: 08-2020
Abstract: This study compared lower-limb muscle function, defined as the contributions of muscles to center-of-mass support and braking, during a single-leg hopping task in anterior cruciate ligament-reconstructed (ACLR) in iduals and uninjured controls. In total, 65 ACLR in iduals and 32 controls underwent a standardized anticipated single-leg forward hop. Kinematics and ground reaction force data were input into musculoskeletal models to calculate muscle forces and to quantify muscle function by decomposing the vertical (support) and fore-aft (braking) ground reaction force components into contributions by in idual lower-limb muscles. Four major muscles, the vasti, soleus, gluteus medius, and gluteus maximus, were primarily involved in support and braking in both ACLR and uninjured groups. However, although the ACLR group demonstrated lower peak forces for these muscles (all P s .001, except gluteus maximus, P = .767), magnitude differences in these muscles’ contributions to support and braking were not significant. ACLR in iduals demonstrated higher erector spinae ( P = .012) and hamstrings forces ( P = .085) to maintain a straighter, stiffer landing posture with more forward lumbar flexion. This altered landing posture may have enabled the ACLR group to achieve similar muscle function to controls, despite muscle force deficits. Our findings may benefit rehabilitation and the development of interventions to enable faster and safer return to sport.
Publisher: BMJ
Date: 03-02-2022
DOI: 10.1136/BJSPORTS-2021-104686
Abstract: To systematically review and synthesise patellofemoral joint reaction force (PFJRF) in healthy in iduals and those with patellofemoral pain and osteoarthritis (OA), during everyday activities, therapeutic exercises and with physical interventions (eg, foot orthotics, footwear, taping, bracing). A systematic review with meta-analysis. Medline, Embase, Scopus, CINAHL, SportDiscus and Cochrane Library databases were searched. Observational and interventional studies reporting PFJRF during everyday activities, therapeutic exercises, and physical interventions. In healthy in iduals, the weighted average of mean (±SD) peak PFJRF for everyday activities were: walking 0.9±0.4 body weight (BW), stair ascent 3.2±0.7 BW, stair descent 2.8±0.5 BW and running 5.2±1.2 BW. In those with patellofemoral pain, peak PFJRF were: walking 0.8±0.2 BW, stair ascent 2.5±0.5 BW, stair descent 2.6±0.5 BW, running 4.1±0.9 BW. Only single studies reported peak PFJRF during everyday activities in in iduals with patellofemoral OA/articular cartilage defects (walking 1.3±0.5 BW, stair ascent 1.6±0.4 BW, stair descent 1.0±0.5 BW). The PFJRF was reported for many different exercises and physical interventions however, considerable variability precluded any pooled estimates. Everyday activities and exercises involving larger knee flexion (eg, squatting) expose the patellofemoral joint to higher PFJRF than those involving smaller knee flexion (eg, walking). There were no discernable differences in peak PFJRF during everyday activities between healthy in iduals and those with patellofemoral pain/OA. The information on PFJRF may be used to select appropriate variations of exercises and physical interventions.
Publisher: Wiley
Date: 29-03-2012
DOI: 10.1002/JOR.22082
Abstract: The aims of this study were to evaluate and explain the in idual muscle contributions to the medial and lateral knee compartment forces during gait, and to determine whether these quantities could be inferred from their contributions to the external knee adduction moment. Gait data from eight healthy male subjects were used to compute each in idual muscle contribution to the external knee adduction moment, the net tibiofemoral joint reaction force, and reaction moment. The in idual muscle contributions to the medial and lateral compartment forces were then found using a least-squares approach. While knee-spanning muscles were the primary contributors, non-knee-spanning muscles (e.g., the gluteus medius) also contributed substantially to the medial compartment compressive force. Furthermore, knee-spanning muscles tended to compress both compartments, while most non-knee-spanning muscles tended to compress the medial compartment but unload the lateral compartment. Muscle contributions to the external knee adduction moment, particularly those from knee-spanning muscles, did not accurately reflect their tendencies to compress or unload the medial compartment. This finding may further explain why gait modifications may reduce the knee adduction moment without necessarily decreasing the medial compartment force.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 07-04-2022
DOI: 10.1007/S00227-022-04036-9
Abstract: Tropicalization is rapidly restructuring subtropical marine communities. A key driver for tropicalization is changes in herbivory pressure that are linked with degrading ecosystem stability. Consequently, subtropical algal beds are being displaced by climate-mediated colonisation of coral communities. This process is thought to be aided by the elevated herbivory resulting from tropicalization, but the relative contribution to herbivory by different taxa is not fully understood. Evaluating herbivory pressure and its effect on coral cover and rugosity across a subtropical latitudinal gradient will help predict how these processes may change with further tropicalization and ocean warming. Herbivory pressure exerted by fishes and urchins across this subtropical latitudinal gradient remains unquantified. Using in-situ feeding observations, we quantify fish and urchin herbivory pressure at seven sites across non-accreting coral communities, and warmer accreting coral reefs in southern Japan. We then relate herbivory pressure to respective fish and urchin community structure and coral cover and rugosity. Urchin herbivory is greater on non-accreting coral communities than on true coral accreting reefs a result which is reversed for fish herbivory. Overall, herbivory pressure is greater on accreting coral reefs than on coral non-accreting communities, but is dependent on reef characteristics as community structures differ more strongly among reefs than between regions. These factors are linked to coral cover and rugosity that differ between reefs, but not between climatic regions, further emphasising the influence of local factors on the benthic cover and the associated fish and urchin community, and thus herbivory pressure. Our findings provide a foundation for understanding how non-accreting coral communities may respond to ongoing tropicalization, given the fish and invertebrate herbivores they host.
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.PTSP.2021.10.011
Abstract: Examine whether football players with hip and/or groin (hip/groin) pain have impaired running biomechanics when compared to pain-free players, analysing men and women independently. Cross-sectional. Biomechanics laboratory. Seventy-eight (62 men, 16 women) football players with >6months of hip/groin pain and a positive flexion-adduction-internal rotation test and 38 (25 men, 13 women) asymptomatic players. Pelvis angles and hip, knee, and ankle joint angles and moments were analysed during the stance phase of overground running at 3-3.5 m⋅s Symptomatic football players did not display significant differences in pelvis angles or lower-limb joint angles, moments, or moment impulses during the stance phase of running, when compared to asymptomatic players of the same sex. Our large s le of football players with hip/groin pain who were still participating in competitive sport displayed similar running biomechanics to asymptomatic players. Impaired running biomechanics might exist in people with worse hip/groin pain, warranting future investigation.
Publisher: Elsevier BV
Date: 11-2022
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Prasanna Sritharan.