Papers by J. Astephen-wilson
Osteoarthritis and Cartilage, 2022
Osteoarthritis and Cartilage, 2020
Osteoarthritis and Cartilage, 2019
Osteoarthritis and Cartilage, 2018
Osteoarthritis and Cartilage, 2018
Osteoarthritis and Cartilage, 2017
Osteoarthritis and Cartilage, 2017
Osteoarthritis and Cartilage, 2017
Purpose: Biomechanical factors have been shown to be associated with knee osteoarthritis (KOA). A... more Purpose: Biomechanical factors have been shown to be associated with knee osteoarthritis (KOA). Abnormal joint loading is considered to be at the heart of adverse biomechanics in KOA. However, a large variety of measures have been used to quantify abnormal joint loading. The study aim was to estimate the association of different measures of abnormal joint loading with the development of KOA. Methods: MEDLINE, EMBASE, CINAHL and SPORTDiscus have been searched from inception up to August 2015. Cohort studies, case-control studies and cross-sectional studies examining the association between abnormal joint loading and KOA were eligible. Two reviewers independently screened articles obtained by the search for eligibility. Measures for abnormal joint loading were varus thrust, valgus thrust, knee adduction moment (KADM), knee abduction moment (KABM), knee flexion moment (KFM), knee extension moment (KEM), knee internal rotation moment (KIRM) and knee external rotation moment (KERM). The association between different measures of abnormal joint loading and the development of KOA was estimated as Odds-Ratio (OR) and combined in meta-analyses using a random effects model. Heterogeneity was estimated as the I-squared statistics measuring the proportion of inconsistency in the combined estimates due to between-study heterogeneity. PROSPERO registration number: CRD42015025092. Results: We identified 26 studies examining the association of abnormal joint loading with KOA. All studies were cross-sectional. KADM and KFM were reported most frequently. Due to large
Clinical Biomechanics, 2017
Corrigendum to "Obesity is associated with higher absolute tibiofemoral contact and muscle forces... more Corrigendum to "Obesity is associated with higher absolute tibiofemoral contact and muscle forces during gait with and without knee osteoarthritis" [Clin. Biomech. Jan; 31 (2016) 79-86]
Osteoarthritis and Cartilage, 2016
Journal of Electromyography and Kinesiology, 2015
To examine the effect of obesity and its potential interaction with knee OA presence on the elect... more To examine the effect of obesity and its potential interaction with knee OA presence on the electromyography patterns of the major knee joint periarticular muscles during walking. Scope: One hundred and eighteen asymptomatic adults and 177 adults with moderate knee osteoarthritis were subdivided into categories of healthy weight (n = 77; 20 kg/m2 < BMI < 25 kg/m2), overweight (n = 117; 25 kg/m2 6 BMI < 30 kg/m2), and obese (n = 101; BMIP30 kg/m2 based on their body mass index (BMI). All individuals underwent a three-dimensional gait analysis. Surface electromyograms from the lateral and medial gastrocnemii, lateral and medial hamstrings, vastus lateralis, vastus medialis, and rectus femoris were recorded during self-selected speed walking. Principal component analysis was used to extract major features of amplitude and temporal pattern variability from the electromyograms of each muscle group (gastrocnemii, quadriceps, hamstrings separately). Analysis of variance models tested for main BMI category effects and interaction effects for these features (a = 0.05). Statistically significant BMI category (i.e. obesity) effects were found for features that described more prolonged activations of the gastrocnemii and quadriceps muscles during the stance phase of gait with obesity (P < 0.05). Conclusions: Obesity was associated with prolonged activation of quadriceps and gastrocnemii, which can result in prolonged knee joint contact loading, and thereby may contribute to the predisposition of knee OA development and progression in obese individuals.
Osteoarthritis and Cartilage, 2014
approximately 3 minutes per knee and produced reasonable contact stress distributions, consistent... more approximately 3 minutes per knee and produced reasonable contact stress distributions, consistent with our previous reports (Fig. 2). Conclusions: The integration of cone beam CT capabilities into a relatively inexpensive (compared to standard CT), upright, small footprint device has the potential to shift the diagnostic and treatment paradigm by introducing low-dose WBCT of the knees to the clinic. In-clinic WBCT also provides groundbreaking opportunities to incorporate contact stress assessments of patients' knees. The accuracy of the WBCT-based contact stress estimates remains to be established and is the subject of ongoing study.
Clinical Biomechanics, 2016
Background Obesity is an important risk factor for knee osteoarthritis initiation and progression... more Background Obesity is an important risk factor for knee osteoarthritis initiation and progression. However, it is unclear how obesity may directly affect the mechanical loading environment of the knee joint, initiating or progressing joint degeneration. The objective of this study was to investigate the interacting role of obesity and moderate knee osteoarthritis presence on tibiofemoral contact forces and muscle forces within the knee joint during walking gait. Methods Three-dimensional gait analysis was performed on 80 asymptomatic participants and 115 individuals diagnosed with moderate knee osteoarthritis. Each group was divided into three body mass index categories: healthy weight (body mass index < 25), overweight (25 ≤ body mass index ≤ 30), and obese (body mass index > 30). Tibiofemoral anterior-posterior shear and compressive forces, as well as quadriceps, hamstrings and gastrocnemius muscle forces, were estimated based on a sagittal plane contact force model. Peak contact and muscle forces during gait were compared between groups, as well as the interaction between disease presence and body mass index category, using a two-factor analysis of variance. Findings There were significant osteoarthritis effects in peak shear, gastrocnemius and quadriceps forces only when they were normalized to body mass, and there were significant BMI effects in peak shear, compression, gastrocnemius and hamstrings forces only in absolute, non-normalized forces. There was a significant interaction effect in peak quadriceps muscle forces, with higher forces in overweight and obese groups compared to asymptomatic healthy weight participants. Interpretation Body mass index was associated with higher absolute tibiofemoral compression and shear forces as well as posterior muscle forces during gait, regardless of moderate osteoarthritis presence or absence. The differences found may contribute to accelerated joint damage with obesity, but with the osteoarthritic knees less able to accommodate the high loads.
The Bone & Joint Journal
Purpose: The goal of this study was to investigate if musculoskeletal activation patterns measure... more Purpose: The goal of this study was to investigate if musculoskeletal activation patterns measured with electromyography (EMG) are predictive of migration of total knee replacements (TKR) measured with radiostereometric analysis (RSA). Method: 37 TKR patients who were part of a larger randomized controlled RSA trial were recruited to this study. Study participants had been randomized to receive the Nexgen LPS Trabecular Metal tibial monoblock component (n = 19), or the cemented NexGen Option Stemmed tibial component (n = 18) (Zimmer, Warsaw IN). Ethics approval was received from the institutional review board. In the week prior to their surgery, the patients went to the dynamics of human motion laboratory and underwent EMG data collection. Surface electrodes were placed over the vastus lateralis, vastus medialis, rectus femoris, the lateral and medial hamstrings, and the lateral and medial gastrocnemius using standardized placements (Hubley-Kozey et al., 2006). The variability in subject EMG patterns was captured with a set of discrete scores that represented weightings on objectively-extracted features of the gait waveform data using principal component analysis (PCA). Within four days of surgery and at six months post-operatively, patients had bi-planar knee x-rays taken. RSA analysis was performed with MB-RSA (MEDIS, Leiden). RSA results were reported as maximum total point motion (MTPM), and six degrees of freedom translations and rotations at six months. Results: A correlation was found between the third principle component of the lateral gastrocnemius muscle (representing high gastrocnemius activation in late stance) and the anterior migration of the component (R2=0.247 P=0.002). A correlation was found between the vastus medialis principle component three (representing low vastus medialis activation in late stance) and the anterior migration of the component (R2= 0.338, P=0.000). A stepwise regression model was developed for anterior migration of the tibial component. To reduce the number of terms in the model only the two EMG variables that were correlated with anterior migration, implant type and BMI were entered leaving four possible terms. The stepwise regression eliminated all variables but the lateral gastrocnemius and the vastus medialis. The regression equation was Anterior-Posterior Migration = 0.01 +0.12*Vastus Medialis PC3 + 0.074*Lateral Gastrocnemius PC3 (R2=0.487, R2 Adj=0.457, P<0.0001) Conclusion: It has previously been shown that anterior shear on the tibial component of TKR is temporally localized to the last third of stance phase of gait. Both the gastrocnemius and vastus muscle groups have the ability to produce large anterior posterior shear on an the knee during late stance. This result shows that variables which capture the temporal activation patterns of these muscles preoperatively are related to the migration of the tibial component of TKR postoperatively. This may have implications for rehabilitation of these patients.
Osteoarthritis and Cartilage, 2015
Osteoarthritis and Cartilage, 2015
the effect of the OA model on bioluminescence, total pixel intensities were compared using single... more the effect of the OA model on bioluminescence, total pixel intensities were compared using single factor ANOVA (n¼10 knees) and correlation analysis. Untargeted analysis was used to reveal global changes in the metabolome, whereas the targeted analysis focused on changes iñ 40 metabolites involved in central energy metabolism. Comparisons between UE and E mice were made using a false discovery rate (FDR) of 0.05. Metabolite intensities ere compared for each group to determine the effects of OA using ANOVA, principal components analysis (PCA), and two-sample Kolmogorov-Smirnov (KS) distribution tests. Results: Following day 10 of the exercise protocol, significant differences in bioluminescence were found between both UE knee groups and the EL knee group (Figure 1A). Significant differences were also identified between EL and ER knee groups. There was a significant, negative correlation with time after one week of exercise, suggesting the onset of cartilage deterioration (Figure 1B-C). Untargeted LC-MS analysis revealed distinct metabolic differences between UE and E groups. Two-sample KS tests revealed significant differences between EL and ER spectra distributions (p< 0.05), whereas no difference were found between UEL and UER distributions (p¼0.626) (Figure 2A). For UE mice, only 1 metabolite was significantly different in UER joints that was not found in UEL joints, whereas 16 metabolites were distinct in UEL joints that were not in UER joints (Figure 2B). For E mice, there were 176 significant metabolites in ER samples that were not found in EL samples, whereas 280 metabolites in EL samples that were not in ER samples (Figure 2B). PCA found distinct differences between sample groups (Figure 2C). Conclusions: The decrease in bioluminescent signal in the EL mouse joints suggests the potential onset of OA and the ability to monitor cartilage deterioration in vivo. The differences between EL and ER joints suggesting the effectiveness for using this combined destabilization surgery and intensive exercise model as an OA model. The distinct differences in metabolite expression indicate further separation of the two groups of mice. Future studies will examine potentially causal metabolomic mechanisms by which cartilage deteriorates.
Osteoarthritis and Cartilage, 2015
throughout stance (rho¼0.626, p¼0.017)(Fig.2) and approached statistical significance for the med... more throughout stance (rho¼0.626, p¼0.017)(Fig.2) and approached statistical significance for the medial shift in COP during the first half of stance(rho¼0.490, p¼0.075). Subjects who responded to the flexible shoe intervention (n¼11), defined as more than a 5% reduction in KAM at 12 weeks compared to their own shoes at baseline, had a greater medial shift in barefoot COP than subjects who did not respond(n¼3) (p¼0.008)(Fig 2). Conclusions: Over 12 weeks of use, walking with flexible shoes significantly reduces loading at the medial tibiofemoral joint in participants with knee OA and shifts the foot COP medially during barefoot walking. This medialization in foot COP is directly associated with the reduction in dynamic medial knee loading. Understanding these relationships may help design future biomechanical interventions for knee OA as well as make recommendations regarding choice of footwear.
The Journal of arthroplasty, 2015
The future of total knee arthroplasty (TKA) surgery will involve planning that incorporates more ... more The future of total knee arthroplasty (TKA) surgery will involve planning that incorporates more patient-specific characteristics. Despite known biological, morphological, and functional differences between men and women, there has been little investigation into knee joint biomechanical and neuromuscular differences between men and women with osteoarthritis, and none that have examined sex-specific biomechanical and neuromuscular responses to TKA surgery. The objective of this study was to examine sex-associated differences in knee kinematics, kinetics and neuromuscular patterns during gait before and after TKA. Fifty-two patients with end-stage knee OA (28 women, 24 men) underwent gait and neuromuscular analysis within the week prior to and one year after surgery. A number of sex-specific differences were identified which suggest a different manifestation of end-stage knee OA between the sexes.
Osteoarthritis and Cartilage, 2012
Objective: Obesity is a highly cited risk factor for knee osteoarthritis (OA), but its role in kn... more Objective: Obesity is a highly cited risk factor for knee osteoarthritis (OA), but its role in knee OA pathogenesis and progression is not as clear. Excess weight may contribute to an increased mechanical burden and altered dynamic movement and loading patterns at the knee. The objective of this study was to examine the interacting role of moderate knee OA disease presence and obesity on knee joint mechanics during gait. Methods: Gait analysis was performed on 104 asymptomatic and 140 individuals with moderate knee OA. Each subject group was divided into three body mass categories based on body mass index (BMI): healthy weight (BMI < 25), overweight (25 BMI 30), and obese (BMI > 30). Three-dimensional knee joint angles and net external knee joint moments were calculated and waveform principal component analysis (PCA) was applied to extract major patterns of variability from each. PC scores for major patterns were compared between groups using a two-factor ANOVA. Results: Significant BMI main effects were found in the pattern of the knee adduction moment, the knee flexion moment, and the knee rotation moment during gait. Two interaction effects between moderate OA disease presence and BMI were also found that described different changes in the knee flexion moment and the knee flexion angle with increased BMI with and without knee OA. Conclusion: Our results suggest that increased BMI is associated with different changes in biomechanical patterns of the knee joint during gait depending on the presence of moderate knee OA.
Osteoarthritis and Cartilage, 2014
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Papers by J. Astephen-wilson