Pub Date : 2026-02-03DOI: 10.1016/j.clinbiomech.2026.106779
Steven Phu, Daina L Sturnieks, Stephen R Lord, Yoshiro Okubo
Background: Slips lead to many falls in older adults. This study aimed to determine the impact of age on muscle and kinematic responses following an unpredictable forward slip while walking.
Methods: A cross-sectional study was conducted with 127 adults (25 young and 102 older) exposed to a single unpredictable forward slip, induced at foot-strike while walking. Bilateral lower limb muscle activity was measured via electromyography and gait kinematics were measured via motion capture.
Findings: Compared to young, older adults displayed greater relative muscle activity and higher relative centre of mass during walking prior to the slip onset (P < 0.05). Following the slip, older adults experienced slips with greater velocity, displayed longer muscle onset latency and time to peak activity of the hamstrings on the non-slipped (contralateral) limb and greater peak activity magnitudes of the gastrocnemius bilaterally (P < 0.05). Older adults also spent more time in double-limb stance (P = 0.001), took a slower second recovery step (P = 0.006), and displayed greater harness loading (P = 0.005).
Interpretation: Older adults had inferior muscle and kinematic responses to an unpredictable forward slip compared to young. Delayed activation of the contralateral limb knee flexors and hip extensors may lead to greater instability, more severe slips and an increased risk of falls in older adults.
{"title":"The impact of age on muscle and kinematic responses following an unpredictable forward slip while walking.","authors":"Steven Phu, Daina L Sturnieks, Stephen R Lord, Yoshiro Okubo","doi":"10.1016/j.clinbiomech.2026.106779","DOIUrl":"https://doi.org/10.1016/j.clinbiomech.2026.106779","url":null,"abstract":"<p><strong>Background: </strong>Slips lead to many falls in older adults. This study aimed to determine the impact of age on muscle and kinematic responses following an unpredictable forward slip while walking.</p><p><strong>Methods: </strong>A cross-sectional study was conducted with 127 adults (25 young and 102 older) exposed to a single unpredictable forward slip, induced at foot-strike while walking. Bilateral lower limb muscle activity was measured via electromyography and gait kinematics were measured via motion capture.</p><p><strong>Findings: </strong>Compared to young, older adults displayed greater relative muscle activity and higher relative centre of mass during walking prior to the slip onset (P < 0.05). Following the slip, older adults experienced slips with greater velocity, displayed longer muscle onset latency and time to peak activity of the hamstrings on the non-slipped (contralateral) limb and greater peak activity magnitudes of the gastrocnemius bilaterally (P < 0.05). Older adults also spent more time in double-limb stance (P = 0.001), took a slower second recovery step (P = 0.006), and displayed greater harness loading (P = 0.005).</p><p><strong>Interpretation: </strong>Older adults had inferior muscle and kinematic responses to an unpredictable forward slip compared to young. Delayed activation of the contralateral limb knee flexors and hip extensors may lead to greater instability, more severe slips and an increased risk of falls in older adults.</p>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"134 ","pages":"106779"},"PeriodicalIF":1.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146144488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-31DOI: 10.1016/j.clinbiomech.2026.106775
Carina Gempfer , Gilmar F. Santos , Alexander Hobein , Timo Kuhlgatz , Christof Hurschler , Eike Jakubowitz
Background
Motion analysis plays an important role in clinical decision-making and biomechanical research. Conventional assessments rely on laboratory-based motion capture and force plates, which are accurate but resource-intensive. Wearable sensors combined with artificial neural networks offer a promising alternative for use outside the laboratory, but they must be validated against established systems. The aim of this study was to predict important kinetic gait parameters, such as ground reaction forces, knee joint moments and knee power, using wearable sensors and neural networks. Such an approach may support gait assessment in orthopaedic conditions and enable more responsive adjustment of exoprostheses.
Methods
Thirty-two healthy adults provided informed consent and were instrumented. Standard kinematic and kinetic data were captured using a conventional motion analysis setup, while linear accelerations were recorded synchronously using wearable sensors. These acceleration signals were used as inputs for two neural network models (long short-term memory and multilayer perceptron) to predict kinetic parameters.
Findings
Both models achieved good to very good agreement with the reference system. Pearson correlation coefficients ranged from 0.79 for the knee joint power to 0.99 for anteroposterior ground reaction force. The normalised root mean square errors between 3.1% and 10.3% further demonstrated promising predictive accuracy.
Interpretation
The findings indicate that wearable sensors combined with neural networks can estimate clinically relevant kinetic gait parameters with high accuracy outside a laboratory setting. In the future, such predictions may help standardize dynamic adjustments of exoprostheses, support the diagnosis of orthopaedic conditions and evaluate treatment outcomes.
{"title":"Predicting gait kinetics using 3-degrees of freedom acceleration data and artificial neural networks","authors":"Carina Gempfer , Gilmar F. Santos , Alexander Hobein , Timo Kuhlgatz , Christof Hurschler , Eike Jakubowitz","doi":"10.1016/j.clinbiomech.2026.106775","DOIUrl":"10.1016/j.clinbiomech.2026.106775","url":null,"abstract":"<div><h3>Background</h3><div>Motion analysis plays an important role in clinical decision-making and biomechanical research. Conventional assessments rely on laboratory-based motion capture and force plates, which are accurate but resource-intensive. Wearable sensors combined with artificial neural networks offer a promising alternative for use outside the laboratory, but they must be validated against established systems. The aim of this study was to predict important kinetic gait parameters, such as ground reaction forces, knee joint moments and knee power, using wearable sensors and neural networks. Such an approach may support gait assessment in orthopaedic conditions and enable more responsive adjustment of exoprostheses.</div></div><div><h3>Methods</h3><div>Thirty-two healthy adults provided informed consent and were instrumented. Standard kinematic and kinetic data were captured using a conventional motion analysis setup, while linear accelerations were recorded synchronously using wearable sensors. These acceleration signals were used as inputs for two neural network models (long short-term memory and multilayer perceptron) to predict kinetic parameters.</div></div><div><h3>Findings</h3><div>Both models achieved good to very good agreement with the reference system. Pearson correlation coefficients ranged from 0.79 for the knee joint power to 0.99 for anteroposterior ground reaction force. The normalised root mean square errors between 3.1% and 10.3% further demonstrated promising predictive accuracy.</div></div><div><h3>Interpretation</h3><div>The findings indicate that wearable sensors combined with neural networks can estimate clinically relevant kinetic gait parameters with high accuracy outside a laboratory setting. In the future, such predictions may help standardize dynamic adjustments of exoprostheses, support the diagnosis of orthopaedic conditions and evaluate treatment outcomes.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"134 ","pages":"Article 106775"},"PeriodicalIF":1.4,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-30DOI: 10.1016/j.clinbiomech.2026.106761
T R Goins, Jane E Sullivan, John Fox, Cindy Servello, Katherine Saul
Background: Individuals with a brachial plexus birth injury have changes in optimal muscle length of affected muscles and diminished motion at the elbow and shoulder, impacting active shoulder elevation. The long head of the biceps, a bi-articular muscle, is of particular interest in this population due to its reduced optimal muscle length and simultaneous shortening at the shoulder and elbow during active shoulder elevation. Prior studies have shown immobilization of a joint may improve the moment-generating capacity of a biarticular muscle crossing that joint. The aim of this study was to investigate the impact of joint stabilization on shoulder elevation isometric moment-generating capacity and active and passive fiber force of the long head of the biceps in simulated elbow postures and altered optimal fiber length of the biceps.
Methods: Simulations, via a musculoskeletal model, were used to predict maximum isometric shoulder elevation moment, active-fiber force, and passive-fiber force versus shoulder elevation in stabilized elbow postures from 10° to 120° with a range of optimal muscle lengths from typical to reduced longitudinal length by 30%, 20%, and 10% to the long head of the biceps.
Findings: The highest shoulder elevation moment was produced with optimal fiber length reduced 30% for biceps long head and the elbow stabilized in 30°, causing lower active fiber force, but higher passive fiber force.
Interpretation: Understanding the biomechanical advantage of immobilizing the elbow in a specified posture that improves shoulder elevation in this population, establishes future directions for therapeutic interventions for birth brachial plexus injuries.
{"title":"The effect of elbow posture on biceps function at the shoulder in brachial plexus birth injuries: A computational sensitivity analysis.","authors":"T R Goins, Jane E Sullivan, John Fox, Cindy Servello, Katherine Saul","doi":"10.1016/j.clinbiomech.2026.106761","DOIUrl":"https://doi.org/10.1016/j.clinbiomech.2026.106761","url":null,"abstract":"<p><strong>Background: </strong>Individuals with a brachial plexus birth injury have changes in optimal muscle length of affected muscles and diminished motion at the elbow and shoulder, impacting active shoulder elevation. The long head of the biceps, a bi-articular muscle, is of particular interest in this population due to its reduced optimal muscle length and simultaneous shortening at the shoulder and elbow during active shoulder elevation. Prior studies have shown immobilization of a joint may improve the moment-generating capacity of a biarticular muscle crossing that joint. The aim of this study was to investigate the impact of joint stabilization on shoulder elevation isometric moment-generating capacity and active and passive fiber force of the long head of the biceps in simulated elbow postures and altered optimal fiber length of the biceps.</p><p><strong>Methods: </strong>Simulations, via a musculoskeletal model, were used to predict maximum isometric shoulder elevation moment, active-fiber force, and passive-fiber force versus shoulder elevation in stabilized elbow postures from 10° to 120° with a range of optimal muscle lengths from typical to reduced longitudinal length by 30%, 20%, and 10% to the long head of the biceps.</p><p><strong>Findings: </strong>The highest shoulder elevation moment was produced with optimal fiber length reduced 30% for biceps long head and the elbow stabilized in 30°, causing lower active fiber force, but higher passive fiber force.</p><p><strong>Interpretation: </strong>Understanding the biomechanical advantage of immobilizing the elbow in a specified posture that improves shoulder elevation in this population, establishes future directions for therapeutic interventions for birth brachial plexus injuries.</p>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"106761"},"PeriodicalIF":1.4,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146120993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-29DOI: 10.1016/j.clinbiomech.2026.106772
Amr Seifelnasr, Xiuhua April Si, Jinxiang Xi
Background: Impaired maxillary sinus ventilation promotes secretion stasis and infection risk. How anatomical parameters (ostial diameter (D), length (L), and sinus volume (V)) interact with breathing pattern to shape ventilation has not been systematically studied in anatomically realistic settings.
Methods: Fifteen transparent sinonasal casts were 3D printed spanning three levels of D, L, and V (D1-D3, L1-L3, V1-V3). E-vapor was used to visualize and quantity sinus ventilation under three conditions: breath-hold, quiet breathing, and panting. Two time metrics were quantified: (i) total vapor escape-settling time; and (ii) escape time for the vapor cloud to reach a reference line. Full factorial ANOVA assessed the main effects of anatomical factors and breathing modes and their interactions.
Findings: Breathing mode was the strongest determinant of total clearance (p < 0.001), with panting markedly reducing the ventilation time than quiet breathing and breath-hold (by > two-thirds). Longer canals and larger sinus volumes prolonged retention. For early-stage transport (time to reference line), ostial length had the most influential main effect (p < 0.001), followed by breathing mode, ostial diameter, and sinus volume. Significant two-way interactions were observed, whereas higher-order interactions were limited. Visualizations and pooled distributions (violin plots) corroborated these hierarchies across the parametric space.
Interpretation: Maxillary sinus ventilation reflects coupled anatomical and physiological constraints. Breathing mode dominates sinus ventilation, whereas ostial canal length most strongly governs early escape near the ostium. These results have implications for surgical planning to increase ostial patency and for optimizing breathing maneuvers to promote sinus aeration and clearance.
{"title":"An in vitro parametric study of maxillary sinus ventilation using transparent 3D-printed sinonasal models.","authors":"Amr Seifelnasr, Xiuhua April Si, Jinxiang Xi","doi":"10.1016/j.clinbiomech.2026.106772","DOIUrl":"https://doi.org/10.1016/j.clinbiomech.2026.106772","url":null,"abstract":"<p><strong>Background: </strong>Impaired maxillary sinus ventilation promotes secretion stasis and infection risk. How anatomical parameters (ostial diameter (D), length (L), and sinus volume (V)) interact with breathing pattern to shape ventilation has not been systematically studied in anatomically realistic settings.</p><p><strong>Methods: </strong>Fifteen transparent sinonasal casts were 3D printed spanning three levels of D, L, and V (D1-D3, L1-L3, V1-V3). E-vapor was used to visualize and quantity sinus ventilation under three conditions: breath-hold, quiet breathing, and panting. Two time metrics were quantified: (i) total vapor escape-settling time; and (ii) escape time for the vapor cloud to reach a reference line. Full factorial ANOVA assessed the main effects of anatomical factors and breathing modes and their interactions.</p><p><strong>Findings: </strong>Breathing mode was the strongest determinant of total clearance (p < 0.001), with panting markedly reducing the ventilation time than quiet breathing and breath-hold (by > two-thirds). Longer canals and larger sinus volumes prolonged retention. For early-stage transport (time to reference line), ostial length had the most influential main effect (p < 0.001), followed by breathing mode, ostial diameter, and sinus volume. Significant two-way interactions were observed, whereas higher-order interactions were limited. Visualizations and pooled distributions (violin plots) corroborated these hierarchies across the parametric space.</p><p><strong>Interpretation: </strong>Maxillary sinus ventilation reflects coupled anatomical and physiological constraints. Breathing mode dominates sinus ventilation, whereas ostial canal length most strongly governs early escape near the ostium. These results have implications for surgical planning to increase ostial patency and for optimizing breathing maneuvers to promote sinus aeration and clearance.</p>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"106772"},"PeriodicalIF":1.4,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146108320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-25DOI: 10.1016/j.clinbiomech.2026.106770
Huaning Liu , Lauren Straatman , Kathryn F. Webster , Patrick Ippersiel , Daniel J. Currie , Dalia Grad , Emily G. Wiebenga , Kaylena Ehgoetz Martens , Stacey M. Acker , Monica R. Maly
Background
Fear of movement is common in knee osteoarthritis but its role in reducing physical activity, and how it interacts with pain, remain unclear. The purpose of this study was to investigate how fear of movement affects the relationships between daily step count with each of pain intensity and pain sensitivity in symptomatic knee osteoarthritis.
Methods
Thirty-one participants with symptomatic knee osteoarthritis were included (17 female, 14 male, 0 intersex; age 65.3 [7.0] years, body mass index (BMI) 30.0 [5.0] kg/m^2). Mean daily step count was captured using a commercial 3-axis accelerometer over 7 days. Pain intensity was measured with the pain subscale of the Knee Injury and Osteoarthritis Outcome Score. Pain sensitivity was measured with pressure pain threshold. Fear of movement was self-reported on the Brief Fear of Movement Scale. After adjusting for covariates (age, BMI), regressions tested the associations between step count and pain intensity without, then with, fear of movement and its interactions. The analysis was repeated using pain sensitivity.
Findings
Step count was not significantly associated with pain intensity (R2 = 0.199, p = 0.107) nor with pain sensitivity (R2 = 0.217, p = 0.091). After adding fear of movement and its interactions to the model, the BMI x fear of movement interaction (p = 0.003) explained variance in step count (R2 = 0.512, p = 0.011). Those with greater fear of movement and larger BMI completed fewer steps compared to their peers.
Interpretation
Managing fear of movement may enhance rehabilitation to promote physical activity in knee osteoarthritis.
活动恐惧在膝关节骨性关节炎中很常见，但它在减少体力活动中的作用以及它如何与疼痛相互作用尚不清楚。本研究的目的是探讨运动恐惧如何影响症状性膝骨关节炎患者每日步数与疼痛强度和疼痛敏感性之间的关系。方法31例有症状的膝关节骨性关节炎患者，其中女性17例，男性14例，阴阳人0例，年龄65.3[7.0]岁，体重指数（BMI） 30.0 [5.0] kg/m^2。使用商用3轴加速度计在7天内捕获平均每日步数。用膝关节损伤和骨关节炎结局评分的疼痛亚量表测量疼痛强度。采用压痛阈测量疼痛敏感性。对移动的恐惧在简短移动恐惧量表上自我报告。在调整协变量（年龄、体重指数）后，回归测试了步数和疼痛强度之间的关系，然后测试了运动恐惧及其相互作用。使用疼痛敏感性重复分析。结果：步数与疼痛强度（R2 = 0.199, p = 0.107）和疼痛敏感性（R2 = 0.217, p = 0.091）无显著相关。在模型中加入运动恐惧及其相互作用后，BMI x运动恐惧相互作用（p = 0.003）解释了步数的方差（R2 = 0.512, p = 0.011）。与同龄人相比，那些更害怕运动、身体质量指数更高的人完成的步数更少。解释：控制对运动的恐惧可以促进膝关节骨关节炎患者的身体活动。
{"title":"Fear of movement, obesity and physical activity in knee osteoarthritis","authors":"Huaning Liu , Lauren Straatman , Kathryn F. Webster , Patrick Ippersiel , Daniel J. Currie , Dalia Grad , Emily G. Wiebenga , Kaylena Ehgoetz Martens , Stacey M. Acker , Monica R. Maly","doi":"10.1016/j.clinbiomech.2026.106770","DOIUrl":"10.1016/j.clinbiomech.2026.106770","url":null,"abstract":"<div><h3>Background</h3><div>Fear of movement is common in knee osteoarthritis but its role in reducing physical activity, and how it interacts with pain, remain unclear. The purpose of this study was to investigate how fear of movement affects the relationships between daily step count with each of pain intensity and pain sensitivity in symptomatic knee osteoarthritis.</div></div><div><h3>Methods</h3><div>Thirty-one participants with symptomatic knee osteoarthritis were included (17 female, 14 male, 0 intersex; age 65.3 [7.0] years, body mass index (BMI) 30.0 [5.0] kg/m^2). Mean daily step count was captured using a commercial 3-axis accelerometer over 7 days. Pain intensity was measured with the pain subscale of the Knee Injury and Osteoarthritis Outcome Score. Pain sensitivity was measured with pressure pain threshold. Fear of movement was self-reported on the Brief Fear of Movement Scale. After adjusting for covariates (age, BMI), regressions tested the associations between step count and pain intensity without, then with, fear of movement and its interactions. The analysis was repeated using pain sensitivity.</div></div><div><h3>Findings</h3><div>Step count was not significantly associated with pain intensity (R<sup>2</sup> = 0.199, <em>p</em> = 0.107) nor with pain sensitivity (R<sup>2</sup> = 0.217, <em>p</em> = 0.091). After adding fear of movement and its interactions to the model, the BMI x fear of movement interaction (<em>p</em> = 0.003) explained variance in step count (R<sup>2</sup> = 0.512, <em>p</em> = 0.011). Those with greater fear of movement and larger BMI completed fewer steps compared to their peers.</div></div><div><h3>Interpretation</h3><div>Managing fear of movement may enhance rehabilitation to promote physical activity in knee osteoarthritis.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106770"},"PeriodicalIF":1.4,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.clinbiomech.2026.106763
Sophia Soehnlen , Yogesh Kumaran , Sara Sadeqi , Sudharshan Tripathi , Angela C. Collins , Carmen E. Quatman
Background
Hip distraction is essential for hip arthroscopy and other orthopaedic surgeries, but high traction forces often lead to complications like nerve injury and soft tissue impairment. Patients with total knee arthroplasties (TKAs) may face increased risk due to altered joint mechanics; however, the impact of specific TKA configurations on knee behavior during distraction is poorly understood.
Methods
A validated finite element model of the pelvis and lower extremity was developed from patient CT and MRI data. Three configurations were modeled: bi-cruciate retaining (BCR), posterior-cruciate retaining (PCR; lacking ACL), and posterior-stabilized (PS; lacking both cruciates). Hip distraction was simulated with axial traction forces (100–500 N) applied to the distal tibia/fibula with the pelvis fixed proximally. Knee and hip joint displacement and ligament strains were evaluated.
Findings
The BCR model demonstrated the highest knee stiffness. ACL removal (PCR) reduced stiffness more compared to PCL removal. While the amount of hip distraction was consistent across models, PCR and PS knees experienced excessive knee distraction (>12 mm) and ligament strains exceeding 20% before achieving 10 mm of hip distraction. Conversely, the BCR model remained under 10 mm of knee distraction and 15% strain at equivalent hip distraction levels.
Interpretation
Finite element analysis revealed that PCR and PS configurations exhibit knee instability, exceeding soft tissue injury thresholds (>20% strain) within standard clinical traction ranges (250–350 N). The ACL contributed greater to knee complex stiffness in axial traction compared to the PCL. Standard traction forces may pose an iatrogenic risk to PCR and PS patients, suggesting a need for TKA-specific distraction protocols to prevent soft tissue failure.
{"title":"Predicted effects of hip distraction on knee ligament mechanics following total knee arthroplasty: A finite element analysis","authors":"Sophia Soehnlen , Yogesh Kumaran , Sara Sadeqi , Sudharshan Tripathi , Angela C. Collins , Carmen E. Quatman","doi":"10.1016/j.clinbiomech.2026.106763","DOIUrl":"10.1016/j.clinbiomech.2026.106763","url":null,"abstract":"<div><h3>Background</h3><div>Hip distraction is essential for hip arthroscopy and other orthopaedic surgeries, but high traction forces often lead to complications like nerve injury and soft tissue impairment. Patients with total knee arthroplasties (TKAs) may face increased risk due to altered joint mechanics; however, the impact of specific TKA configurations on knee behavior during distraction is poorly understood.</div></div><div><h3>Methods</h3><div>A validated finite element model of the pelvis and lower extremity was developed from patient CT and MRI data. Three configurations were modeled: bi-cruciate retaining (BCR), posterior-cruciate retaining (PCR; lacking ACL), and posterior-stabilized (PS; lacking both cruciates). Hip distraction was simulated with axial traction forces (100–500 N) applied to the distal tibia/fibula with the pelvis fixed proximally. Knee and hip joint displacement and ligament strains were evaluated.</div></div><div><h3>Findings</h3><div>The BCR model demonstrated the highest knee stiffness. ACL removal (PCR) reduced stiffness more compared to PCL removal. While the amount of hip distraction was consistent across models, PCR and PS knees experienced excessive knee distraction (>12 mm) and ligament strains exceeding 20% before achieving 10 mm of hip distraction. Conversely, the BCR model remained under 10 mm of knee distraction and 15% strain at equivalent hip distraction levels.</div></div><div><h3>Interpretation</h3><div>Finite element analysis revealed that PCR and PS configurations exhibit knee instability, exceeding soft tissue injury thresholds (>20% strain) within standard clinical traction ranges (250–350 N). The ACL contributed greater to knee complex stiffness in axial traction compared to the PCL. Standard traction forces may pose an iatrogenic risk to PCR and PS patients, suggesting a need for TKA-specific distraction protocols to prevent soft tissue failure<em>.</em></div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106763"},"PeriodicalIF":1.4,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stroke survivors commonly have impairments in balance, coordination, and motor control that increase fall risk and limit independence. The Timed Up and Go test (TUG) is widely used to assess mobility and fall risk, yet total time may miss neurological deficits. The objective was to determine whether component specific kinematic measures from inertial measurement units provide more sensitive indicators of impairment than a time based outcome.
Methods
Forty individuals with sub-acute hemiparetic stroke (mean age 73.4 ± 14.6 years; 18 men, 22 women) performed the TUG at maximal speed while wearing inertial measurement units on the pelvis and the feet. The task was segmented into five components: sit to stand, forward gait, turning, return gait, and stand to sit. Neuromuscular impairment was evaluated with the Stroke Impairment Assessment Set (SIAS). Linear regression examined associations between assessment scores and pelvic angular velocities and linear accelerations, adjusting for age and total test time.
Findings
Higher SIAS scores were associated with greater pelvic roll (B = 1.00, p = 0.003; adjusted R2 = 0.48) and yaw (B = 1.88, p = 0.01; adjusted R2 = 0.27) angular velocities during the turning phase, even after adjustment for age and TUG time. No significant associations were found for linear acceleration metrics or for total TUG time alone.
Interpretation
Phase specific pelvic angular velocities measured by inertial sensors are more sensitive than overall test duration for detecting stroke related motor impairment, particularly during turning. This approach may improve clinical evaluation, support individualized rehabilitation.
中风幸存者通常在平衡、协调和运动控制方面有损伤，这增加了跌倒的风险，限制了独立性。定时起跳测试（TUG）被广泛用于评估活动能力和跌倒风险，但总时间可能会遗漏神经功能缺陷。目的是确定来自惯性测量单元的部件特定运动学测量是否比基于时间的结果提供更敏感的损伤指标。方法40例亚急性偏瘫患者（平均年龄73.4±14.6岁，男18例，女22例）在骨盆和足部佩戴惯性测量装置，以最大速度进行TUG。这项任务分为五个部分：坐到站，向前走，转身，返回步，站到坐。神经肌肉损伤用脑卒中损伤评估集（SIAS）进行评估。线性回归检查了评估分数与骨盆角速度和线性加速度之间的关系，调整了年龄和总测试时间。结果较高的SIAS评分与更大的骨盆侧倾（B = 1.00, p = 0.003；调整R2 = 0.48）和偏航（B = 1.88, p = 0.01；调整R2 = 0.27）角速度相关，即使在调整年龄和TUG时间后也是如此。没有发现线性加速度指标或总拖船时间单独显著关联。解释：惯性传感器测量的特定相位骨盆角速度比检测卒中相关运动损伤的总测试时间更敏感，特别是在转弯时。该方法可改善临床评价，支持个体化康复。
{"title":"Component-specific kinematic analysis of the timed up and go test using inertial measurement units reflects neuromuscular impairments in patients after stroke","authors":"Satoshi Hakukawa , Kanata Yoshihara , Shunsuke Onuma , Masahiro Ishiwatari","doi":"10.1016/j.clinbiomech.2026.106771","DOIUrl":"10.1016/j.clinbiomech.2026.106771","url":null,"abstract":"<div><h3>Background</h3><div>Stroke survivors commonly have impairments in balance, coordination, and motor control that increase fall risk and limit independence. The Timed Up and Go test (TUG) is widely used to assess mobility and fall risk, yet total time may miss neurological deficits. The objective was to determine whether component specific kinematic measures from inertial measurement units provide more sensitive indicators of impairment than a time based outcome.</div></div><div><h3>Methods</h3><div>Forty individuals with sub-acute hemiparetic stroke (mean age 73.4 ± 14.6 years; 18 men, 22 women) performed the TUG at maximal speed while wearing inertial measurement units on the pelvis and the feet. The task was segmented into five components: sit to stand, forward gait, turning, return gait, and stand to sit. Neuromuscular impairment was evaluated with the Stroke Impairment Assessment Set (SIAS). Linear regression examined associations between assessment scores and pelvic angular velocities and linear accelerations, adjusting for age and total test time.</div></div><div><h3>Findings</h3><div>Higher SIAS scores were associated with greater pelvic roll (B = 1.00, <em>p</em> = 0.003; adjusted R<sup>2</sup> = 0.48) and yaw (B = 1.88, <em>p</em> = 0.01; adjusted R<sup>2</sup> = 0.27) angular velocities during the turning phase, even after adjustment for age and TUG time. No significant associations were found for linear acceleration metrics or for total TUG time alone.</div></div><div><h3>Interpretation</h3><div>Phase specific pelvic angular velocities measured by inertial sensors are more sensitive than overall test duration for detecting stroke related motor impairment, particularly during turning. This approach may improve clinical evaluation, support individualized rehabilitation.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106771"},"PeriodicalIF":1.4,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.clinbiomech.2026.106768
Akino Aoki , Kohei Koresawa , Yumi No , Masashi Sadakiyo , Satoshi Kubota , Szu-Ping Lee , Kazuyoshi Gamada
Background
To prospectively examine how lower extremity movement patterns during single-leg landings predict anterior cruciate ligament (ACL) injuries in adolescent Japanese basketball players during a 3-year follow-up period.
Methods
44 female basketball players, whose knee kinematics were measured using 2-dimensional video analysis during single-leg jump landings from a box 30 cm high. Peak knee valgus angle and knee wobbling during the landing task were primary measures of injury risk. Knee wobbling, defined as repeated knee valgus/varus movement, was calculated from relative frontal to sagittal motions (RFM) at 6, 12, 18, 24, and 30° of knee flexion. Higher RFM indicates that knee frontal movement is large compared to changes in knee flexion during landing. Knee valgus angle and RFM were compared prospectively between ACL-injured and uninjured athletes during a 3-year follow-up period.
Findings
Peak knee valgus angles at initial contact for injured and uninjured athletes were not significantly different (12.3 ± 2.4° vs. 14.8 ± 4.1°; p = 0.15). Five of six ACL-injured knees (83.3%) presented knee wobbling during landing. RFM at 18° knee flexion was significantly greater in injured athletes (0.42 ± 0.52) compared to uninjured athletes (0.10 ± 0.31; p = 0.02).
Interpretation
While peak knee valgus angle did not predict subsequent ACL injuries, RFM at 18° knee flexion could find the difference between groups. This study suggests that frontal plane knee wobbling may be indicative of impaired lower extremity control and thus a potential screening tool and intervention target for ACL injury prevention in female basketball players.
{"title":"Novel measures of frontal plane knee wobbling predict anterior cruciate ligament injury in Japanese female basketball players: A prospective pilot study","authors":"Akino Aoki , Kohei Koresawa , Yumi No , Masashi Sadakiyo , Satoshi Kubota , Szu-Ping Lee , Kazuyoshi Gamada","doi":"10.1016/j.clinbiomech.2026.106768","DOIUrl":"10.1016/j.clinbiomech.2026.106768","url":null,"abstract":"<div><h3>Background</h3><div>To prospectively examine how lower extremity movement patterns during single-leg landings predict anterior cruciate ligament (ACL) injuries in adolescent Japanese basketball players during a 3-year follow-up period.</div></div><div><h3>Methods</h3><div>44 female basketball players, whose knee kinematics were measured using 2-dimensional video analysis during single-leg jump landings from a box 30 cm high. Peak knee valgus angle and knee wobbling during the landing task were primary measures of injury risk. Knee wobbling, defined as repeated knee valgus/varus movement, was calculated from relative frontal to sagittal motions (RFM) at 6, 12, 18, 24, and 30° of knee flexion. Higher RFM indicates that knee frontal movement is large compared to changes in knee flexion during landing. Knee valgus angle and RFM were compared prospectively between ACL-injured and uninjured athletes during a 3-year follow-up period.</div></div><div><h3>Findings</h3><div>Peak knee valgus angles at initial contact for injured and uninjured athletes were not significantly different (12.3 ± 2.4° vs. 14.8 ± 4.1°; <em>p</em> = 0.15). Five of six ACL-injured knees (83.3%) presented knee wobbling during landing. RFM at 18° knee flexion was significantly greater in injured athletes (0.42 ± 0.52) compared to uninjured athletes (0.10 ± 0.31; <em>p</em> = 0.02).</div></div><div><h3>Interpretation</h3><div>While peak knee valgus angle did not predict subsequent ACL injuries, RFM at 18° knee flexion could find the difference between groups. This study suggests that frontal plane knee wobbling may be indicative of impaired lower extremity control and thus a potential screening tool and intervention target for ACL injury prevention in female basketball players.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106768"},"PeriodicalIF":1.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.clinbiomech.2026.106767
Seth J. Kussow , Rich J. Lisonbee , Bergen Braun , Jared L. Zitnay , Megan K. Mills , Stephen K. Aoki , Travis G. Maak , Penny R. Atkins , Andrew E. Anderson
Background
Spinopelvic morphology and alignment have been theorized to play a role in causing femoroacetabular impingement syndrome symptoms in individuals with cam morphology. However, prior studies have used hip morphological and alignment measurements that are interdependent, limiting understanding of form-function relationships.
Methods
Statistical shape modeling and biplane videoradiography were used for accurate, 3D assessment of femur and pelvis morphology and in vivo standing hip and pelvis orientation among individuals with and without cam morphology and impingement symptoms. Group differences in standing posture and shape were assessed, along with correlations between shape and posture.
Findings
Patients stood with less anterior pelvic tilt and greater hip extension than asymptomatic individuals without cam morphology. A more patient-like proximal femur shape was correlated with less anterior pelvic tilt. Asymptomatic individuals with cam morphology showed no standing posture differences but had a unique pelvic shape featuring an internally rotated ilium. Further, femur and pelvis anatomical features, primarily describing changes at hip-crossing muscle attachment sites and the sacroiliac region, showed significant associations with hip and pelvis orientation in the sagittal and frontal planes.
Interpretation
Patients with symptomatic impingement due to cam morphology may preemptively adopt less anterior pelvic tilt to enable functional hip range of motion. The associations between shape and standing posture may identify patients best suited for treatment involving pelvic posture modification. Results support further investigation of hip crossing muscle characteristics and spinopelvic alignment during dynamic activities to strengthen understanding of the underlying mechanisms responsible for symptoms in patients with femoroacetabular impingement syndrome.
{"title":"Standing anterior pelvic tilt is correlated with the proximal femur shape of individuals with cam morphology","authors":"Seth J. Kussow , Rich J. Lisonbee , Bergen Braun , Jared L. Zitnay , Megan K. Mills , Stephen K. Aoki , Travis G. Maak , Penny R. Atkins , Andrew E. Anderson","doi":"10.1016/j.clinbiomech.2026.106767","DOIUrl":"10.1016/j.clinbiomech.2026.106767","url":null,"abstract":"<div><h3>Background</h3><div>Spinopelvic morphology and alignment have been theorized to play a role in causing femoroacetabular impingement syndrome symptoms in individuals with cam morphology. However, prior studies have used hip morphological and alignment measurements that are interdependent, limiting understanding of form-function relationships.</div></div><div><h3>Methods</h3><div>Statistical shape modeling and biplane videoradiography were used for accurate, 3D assessment of femur and pelvis morphology and in vivo standing hip and pelvis orientation among individuals with and without cam morphology and impingement symptoms. Group differences in standing posture and shape were assessed, along with correlations between shape and posture.</div></div><div><h3>Findings</h3><div>Patients stood with less anterior pelvic tilt and greater hip extension than asymptomatic individuals without cam morphology. A more patient-like proximal femur shape was correlated with less anterior pelvic tilt. Asymptomatic individuals with cam morphology showed no standing posture differences but had a unique pelvic shape featuring an internally rotated ilium. Further, femur and pelvis anatomical features, primarily describing changes at hip-crossing muscle attachment sites and the sacroiliac region, showed significant associations with hip and pelvis orientation in the sagittal and frontal planes.</div></div><div><h3>Interpretation</h3><div>Patients with symptomatic impingement due to cam morphology may preemptively adopt less anterior pelvic tilt to enable functional hip range of motion. The associations between shape and standing posture may identify patients best suited for treatment involving pelvic posture modification. Results support further investigation of hip crossing muscle characteristics and spinopelvic alignment during dynamic activities to strengthen understanding of the underlying mechanisms responsible for symptoms in patients with femoroacetabular impingement syndrome.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106767"},"PeriodicalIF":1.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.clinbiomech.2026.106764
Yuet Yee Or , Hylton B. Menz , Shannon E. Munteanu , Karl B. Landorf , Michelle R. Kaminski , Polly Q.X. Lim
Background
Midfoot osteoarthritis is common and results in pain and disability. We compared the effects of an arch contouring foot orthosis and a flat sham insert on plantar loading in people with midfoot osteoarthritis.
Methods
Plantar loading was collected while walking with: (i) shoe-only, and either (ii) a flat sham insert or (iii) an arch contouring orthosis. Differences within groups were tested using paired samples t-tests, and differences between groups were tested using analyses of covariance. Effect sizes for within-group comparisons were calculated using Cohen's d.
Findings
Forty-two adults were analysed (38 women and 4 men, mean ± SD age 66.3 ± 6.7 years). The arch contouring orthosis significantly increased contact area (adjusted mean difference [MD] 3.0 cm2, 95% confidence interval [95% CI] 0.0 to 5.9; p = 0.047) and maximum force (MD 30.3 N, 95% CI 16.0 to 44.7; p < 0.001) at the medial midfoot, decreased maximum force at the lateral forefoot (MD -28.2 N, 95% CI -42.9 to −13.5; p < 0.001), decreased peak pressure at the heel (MD -36.2 kPa, 95% CI -65.1 to −7.4; p = 0.015) and increased peak pressure at the medial midfoot (MD 19.8 kPa, 95% CI 7.0 to 32.5; p = 0.003). Within the arch contouring orthosis group, increases in maximum force and peak pressure at the medial midfoot were large and very large (d = 0.90 and 1.21, respectively).
Interpretation
The arch contouring orthosis increased plantar loading at the medial midfoot and decreased loading at the heel. Further studies are required to investigate if these effects are related to symptomatic improvements.
背景：足中部骨关节炎是一种常见的疾病，可导致疼痛和残疾。我们比较了足弓轮廓矫形器和假假平植入物对足中部骨关节炎患者足底负荷的影响。方法：在行走时收集足底负荷：(i)仅穿鞋，（ii）平板假体插入物或（iii）弓形矫形器。组内差异采用配对样本t检验，组间差异采用协方差分析。使用Cohen's d计算组内比较的效应量。研究结果：分析了42名成年人（38名女性和4名男性，平均±SD年龄66.3±6.7岁）。足弓轮廓矫形器显著增加了接触面积（调整后的平均差[MD] 3.0 cm2, 95%可信区间[95% CI] 0.0至5.9;p = 0.047）和最大力(MD 30.3 N, 95% CI 16.0至44.7；p解释：足弓轮廓矫形器增加了内侧中足的足底负荷，减少了脚跟负荷。需要进一步的研究来调查这些影响是否与症状改善有关。
{"title":"Effects of a contoured foot orthosis versus a flat sham insert on plantar loading in midfoot osteoarthritis","authors":"Yuet Yee Or , Hylton B. Menz , Shannon E. Munteanu , Karl B. Landorf , Michelle R. Kaminski , Polly Q.X. Lim","doi":"10.1016/j.clinbiomech.2026.106764","DOIUrl":"10.1016/j.clinbiomech.2026.106764","url":null,"abstract":"<div><h3>Background</h3><div>Midfoot osteoarthritis is common and results in pain and disability. We compared the effects of an arch contouring foot orthosis and a flat sham insert on plantar loading in people with midfoot osteoarthritis.</div></div><div><h3>Methods</h3><div>Plantar loading was collected while walking with: (i) shoe-only, and either (ii) a flat sham insert or (iii) an arch contouring orthosis. Differences within groups were tested using paired samples <em>t</em>-tests, and differences between groups were tested using analyses of covariance. Effect sizes for within-group comparisons were calculated using Cohen's <em>d</em>.</div></div><div><h3>Findings</h3><div>Forty-two adults were analysed (38 women and 4 men, mean ± SD age 66.3 ± 6.7 years). The arch contouring orthosis significantly increased contact area (adjusted mean difference [MD] 3.0 cm<sup>2</sup>, 95% confidence interval [95% CI] 0.0 to 5.9; <em>p</em> = 0.047) and maximum force (MD 30.3 N, 95% CI 16.0 to 44.7; <em>p</em> < 0.001) at the medial midfoot, decreased maximum force at the lateral forefoot (MD <strong>-</strong>28.2 N, 95% CI <strong>-</strong>42.9 to <strong>−</strong>13.5; <em>p</em> < 0.001), decreased peak pressure at the heel (MD <strong>-</strong>36.2 kPa, 95% CI <strong>-</strong>65.1 to <strong>−</strong>7.4; <em>p</em> = 0.015) and increased peak pressure at the medial midfoot (MD 19.8 kPa, 95% CI 7.0 to 32.5; p = 0.003). Within the arch contouring orthosis group, increases in maximum force and peak pressure at the medial midfoot were large and very large (<em>d</em> = 0.90 and 1.21, respectively).</div></div><div><h3>Interpretation</h3><div>The arch contouring orthosis increased plantar loading at the medial midfoot and decreased loading at the heel. Further studies are required to investigate if these effects are related to symptomatic improvements.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"133 ","pages":"Article 106764"},"PeriodicalIF":1.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146068384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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