ORCID Profile
0000-0003-0145-5042
Current Organisation
University of Southampton
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Publisher: Wiley
Date: 21-07-2010
DOI: 10.1002/MUS.21725
Abstract: Muscle dimension changes on ultrasound imaging (USI) indicate contractile activity. Quadriceps force and rectus femoris (RF) dimensions were examined to assess USI for estimating contraction level. In 15 healthy males, mean age 24.8 years, isometric quadriceps force was measured in 90° knee flexion during submaximal and maximal voluntary contractions (MVCs) and at MVC in extension. Mid-thigh cross-sectional area (CSA), depth and width, and surface electromyography (EMG) of RF were recorded. Muscle width decreased curvilinearly as both force and EMG increased. At MVC, width was 3.2 ± 0.5 cm, 25% smaller than at rest (4.4 ± 0.7 cm), and similar to MVC in extension (-23%). CSA decreased linearly to -18% at MVC. RF thickness increased by only 10% (at 30% to MVC). Similar width changes at MVC in flexion and extension indicate the clinical potential of USI for assessing quadriceps contractility. Sensitivity is limited to assessing strength to within 25% of MVC in young males.
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.MATH.2014.02.002
Abstract: Objective quantification of muscle size can aid clinical assessment when treating musculoskeletal conditions. To date the gold standard of measuring muscle morphology is magnetic resonance imaging (MRI). However, there's a growing body of evidence validating rehabilitative ultrasound imaging (RUSI) against MRI. This study aimed to validate RUSI against MRI for the linear measurements of the distal fibres of vastus medialis muscle in the thigh. Twelve healthy male participants were recruited from a local university population. The distal portion of their right vastus medialis was imaged with the participant in long-sitting, using MRI and RUSI whilst the leg was in extension and neutral hip rotation. Cross sectional area (CSA) and three linear measures were taken from the MRI and these were compared with the same linear measures from RUSI. Statistical analysis included comparison of MRI and RUSI measures using the paired t-test and intra-class correlation coefficients (ICC 3,1). Mean differences between the linear measures taken from the MRI and RUSI were -0.5 mm to 2.9 mm (95% confidence intervals -0.6-8.3 mm), which were not statistically different (p > 0.05) and were highly correlated (ICCs 3,1 0.84-0.94). Correlations between the three linear measurements and muscle CSA ranged from r = 0.23 to 0.87, the greatest being muscle thickness. Multiplying the linear measures did not improve the correlation of 0.87 found for muscle thickness. Linear measures of vastus medialis depth made using RUSI were shown to be as valid as using MRI. Muscle thickness measures using RUSI could be used within an objective assessment of this muscle.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2023
Publisher: Informa UK Limited
Date: 22-04-2015
DOI: 10.1080/10255842.2015.1034115
Abstract: The purpose of this study is to assess changes in subjective and objective function from pre- to post-knee arthroplasty (KA) using a combined classifier technique. Twenty healthy adults (50-80 years) and 31 KA patients (39-81 years) were studied (4 weeks pre- and 6 months post-KA). Questionnaire measures of subjective pain, joint stability, activity and function were collected. Objective functional assessment included goniometry, ultrasound imaging and 3-D motion analysis/inverse modelling of gait and sit-stand. An optimal set of variables were used to classify function using the Cardiff Dempster-Shafer theory (DST) method. Out of s le accuracy of the classifiers ranged between 90% and 94% for segregating healthy in iduals and pre-KA patients. Post-KA subjective function improved with 74% classified as healthy. However, there was minimal improvement in objective measures (23% classified as healthy). The novel use of Cardiff DST segregated KA patients from healthy in iduals and estimated changes in function from pre- to post-surgery. KA patients had improved pain and function post-operation but objective knee joint measures remained different to healthy in iduals.
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.JBIOMECH.2011.09.009
Abstract: Pre-clinical computational testing of total knee replacements (TKRs) often only considers a single patient model with simplified applied loads. In studies of multiple patients, most only take into account geometric differences, especially in studies on the knee. Limited availability of kinetic data means that it is difficult to account for inter-patient variability. Principal component analysis (PCA) based statistical models have been used to capture the variation of a set of data and generate new instances of the data. This study presents a method to create a statistical model of kinetic waveform data. A PCA based statistical model was created of the tibiofemoral joint loads for level gait of preoperative TKR patients using data predicted from a musculoskeletal model. A reconstruction test showed that, using principal components (PCs) representing 95% variance, the median root-mean-squared (RMS) error was <0.1 body weight (BW) for the forces and <0.001 BWm for the moments. Leave-one-out tests were also performed and although the median RMS error increased for each load in comparison to the reconstruction error (maximum was 0.2 BW for the axial force and 0.012 BWm for the varus-valgus moment) these were considered within an acceptable limit. The purpose of creating a statistical model is to be able to s le a large set of data representing a population from a small set of clinical data. Such models can potentially be used in population based studies of TKRs incorporating inter-patient variability.
Publisher: Cold Spring Harbor Laboratory
Date: 18-08-2022
DOI: 10.1101/2022.08.18.504401
Abstract: Preliminary human studies show that reduced skin temperature minimises the risk of mechanically-induced skin damage. However, the mechanisms by which cooling enhances skin tolerance to pressure and shear remain poorly understood. We hypothesized that skin cooling below thermo-neutral conditions will decrease friction at the skin-material interface. To test our hypothesis, we measured the friction coefficient of a thermally pre-conditioned index finger sliding at a normal load (5N) across a plate maintained at three different temperatures (38, 24, and 16□). To quantify the temperature distribution of the skin tissue, we used 3D surface scanning and Optical Coherence Tomography to develop an anatomically-representative thermal model of the finger. Our data indicated that the sliding finger with thermally affected tissues (up to 8mm depth) experienced significantly (p .01) lower frictional forces at 16°C-plate temperature than at the 24°C [-23% (±19% SD)] and 38°C plate interactions [-35% (±11% SD)], respectively. This phenomenon occurred without changes in skin hydration during sliding. Accordingly, our experiments demonstrate thermal modulation of skin friction in the absence of skin-moisture effects. Our complementary experimental and theoretical results provide new insight into thermal modulation of skin friction that can be employed for developing thermal technologies to maintain skin integrity under mechanical loading.
Publisher: British Editorial Society of Bone & Joint Surgery
Date: 09-2013
DOI: 10.1302/2046-3758.29.2000176
Abstract: We aimed to examine the characteristics of deep venous flow in the leg in a cast and the effects of a wearable neuromuscular stimulator (geko FirstKind Ltd) and also to explore the participants’ tolerance of the stimulator. This is an open-label physiological study on ten healthy volunteers. Duplex ultrasonography of the superficial femoral vein measured normal flow and cross-sectional area in the standing and supine positions (with the lower limb initially horizontal and then elevated). Flow measurements were repeated during activation of the geko stimulator placed over the peroneal nerve. The process was repeated after the application of a below-knee cast. Participants evaluated discomfort using a questionnaire (verbal rating score) and a scoring index (visual analogue scale). The geko device was effective in significantly increasing venous blood flow in the lower limb both with a plaster cast (mean difference 11.5 cm/sec -1 p = 0.001 to 0.13) and without a plaster cast (mean difference 7.7 cm/sec -1 p = 0.001 to 0.75). Posture also had a significant effect on peak venous blood flow when the cast was on and the geko inactive (p = 0.003 to 0.69), although these differences were less pronounced than the effect of the geko (mean difference 3.1 cm/sec -1 (-6.5 to 10)). The geko device was well tolerated, with participants generally reporting only mild discomfort using the device. The geko device increases venous blood flow in the lower limb, offering a potential mechanical thromboprolylaxis for patients in a cast. Cite this article: Bone Joint Res 2013 :179–85.
Publisher: Mark Allen Group
Date: 12-03-2020
DOI: 10.12968/BJON.2020.29.5.S36
Abstract: Catherine Milne and colleagues present the findings of their review, ccna2@juno.com
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.MATH.2011.07.001
Abstract: Evidence is currently lacking for guidance on ultrasound transducer configuration (shape) when imaging muscle to measure its size. This study compared measurements made of lumbar multifidus on images obtained using curvilinear and linear transducers. Fifteen asymptomatic males (aged 21-32 years) had their right lumbar multifidus imaged at L3. Two transverse images were taken with two transducers (5 MHz curvilinear and 6 MHz linear), and linear and cross-sectional area (CSA) measurements were made off-line. Reliability of image interpretation was shown using intra-class correlation coefficients (0.78-0.99). Muscle measurements were compared between transducers using Bland and Altman plots and paired t-tests. Relationships between CSA and linear measurements were examined using Pearson's Correlation Coefficients. There were no significant differences (p > 0.05) in the measurements of the two transducers. Thickness and CSA measurements had small differences between transducers, with mean differences of 0.01 cm (SDdiff = 0.21 cm) and 0.03 cm(2) (SDdiff = 0.58 cm(2)) respectively. Width measures had a mean difference of 0.14 cm, with the linear transducer giving larger measures. Significant correlations (p < 0.001) were found between all linear measures and CSA, with both transducers (r = 0.78-0.89). Measurements of multifidus at L3 were not influenced by the configuration of transducers of similar frequency. For the purposes of image interpretation, the curvilinear transducer produced better definition of the lateral muscle border, suggesting it as the preferable transducer for imaging lumbar multifidus.
Publisher: Mark Allen Group
Date: 03-2022
Publisher: Elsevier BV
Date: 10-2023
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2015
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.JBIOMECH.2013.04.021
Abstract: The aim of this study was to investigate the performance of a cementless osseointegrated tibial tray (P.F.C. ® Sigma®, Depuy® Inc, USA) in a general population using finite element (FE) analysis. Computational testing of total knee replacements (TKRs) typically only use a model of a single patient and assume the results can be extrapolated to the general population. In this study, two statistical models (SMs) were used one of the shape and elastic modulus of the tibia, and one of the tibiofemoral joint loads over a gait cycle, to generate a population of FE models. A method was developed to automatically size, position and implant the tibial tray in each tibia, and 328 models were successfully implanted and analysed. The peak strain in the bone of the resected surface was examined and the percentage surface area of bone above yield strain (PSAY) was used to determine the risk of failure of a model. Using an arbitrary threshold of 10% PSAY, the models were ided into two groups ('higher risk' and 'lower risk') in order to explore factors that may influence potential failure. In this study, 17% of models were in the 'higher risk' group and it was found that these models had a lower elastic modulus (mean 275.7MPa), a higher weight (mean 85.3kg), and larger peak loads, of which the axial force was the most significant. This study showed the mean peak strain of the resected surface and PSAY were not significantly different between implant sizes.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.GAITPOST.2010.11.018
Abstract: Knowledge of joint forces and moments is essential for comparisons between healthy people and those with pathological conditions, with observed changes at joints providing basis for a particular intervention. Currently the literature analysing both kinematics and kinetics at the knee has been limited to small s les, typically of young subjects or those who have undergone joint arthroplasty. In this study, we examined tibiofemoral joint (TFJ) kinematics and kinetics during gait, sit-stand-sit, and step-descent in 20 healthy older subjects (aged 53-79 years) using motion capture data and inverse dynamic musculoskeletal models. Mean peak distal-proximal force in the TFJ were 3.1, 1.6, and 3.5 times body weight (N/BW) for gait, sit-stand, and step-descent respectively. There were also significant posterior-anterior forces, with sit-stand activity peaking at 1.6 N/BW. Moments about the TFJ peaked at a mean of 0.07 Nm/BW during the sit-stand activity. One of the most important findings of this study was variability found across the subjects, who spanned a wide age range, showing large standard deviations in all of the activities for both kinematics and kinetics. These data have provided an initial prediction for assessing kinematics and kinetics in the older population. Larger studies are needed to refine the database, in particular to reduce the variability in the results by studying sub-populations, to enable more robust comparisons between healthy and pathological TFJ kinematics and kinetics.
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.CLINBIOMECH.2013.07.014
Abstract: Studies have highlighted asymmetries in knee joint moments in in iduals with osteoarthritis and joint replacements. However, there is a need to investigate the forces at the knee joints to establish the extent of loading asymmetries. Twenty healthy (mean age, 62 range, 55-79 years) and 34 pre- to post-knee arthroplasty (mean age, 64 range, 39-79 years) participants performed gait and sit-stand activities in a motion capture laboratory. Knee joint forces and moments were predicted using inverse dynamics and used to calculate peak loading and impulse data which were normalized to body weight. Comparisons were made between affected and contralateral limbs, and changes from pre- to post-knee arthroplasty. Pre-knee arthroplasty peak vertical knee forces were greater in the contralateral limb compared to the affected limb during both gait 3.5 vs. 3.2 ∗ body weight and sit-stand 1.8 vs. 1.5 ∗ body weight. During gait, peak knee adduction moment asymmetries significantly changed from pre- to post-knee arthroplasty (-0.3 to 0.8 ∗ % body weight ∗ m ∗ height), although differences in vertical knee forces remained. There were no significant changes in loading during sit-stand from pre- to post-knee arthroplasty. The healthy participants showed no noteworthy asymmetries. This study showed loading asymmetries in knee forces between affected and contralateral limbs both pre- and post-knee arthroplasty. Continued over reliance of the contralateral limb could lead to pathology.
Publisher: Mark Allen Group
Date: 02-2020
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Peter Worsley.