Pub Date : 2025-11-21DOI: 10.1016/j.clinbiomech.2025.106719
Robyn M. Hansen , Samantha I. Weiss , Sara L. Arena , Robin M. Queen
Background
Ankle osteoarthritis (OA) affects ∼1 % of the global population and impairs postural stability, increasing fall risk. Total ankle arthroplasty (TAA) is one of the most common surgical treatments, but balance impairments may persist post-op. The study examined differences in load symmetry across time for patients with ankle OA and post-TAA at low (LFR) or high fall risk (HFR) and then compared these groups with healthy controls.
Methods
All participants completed a balance assessment consisting of four static stances: shoulder width (BS), feet together (BFT), semi-tandem, and tandem. Fall risk was determined pre-operatively. Ground reaction forces were collected using force plates (AMTI, Watertown, MA) and load symmetry was calculated using the normalized symmetry index (NSI). A mixed effects model analyzed interactions between group (LFR, HFR) and time (pre-op, post1yr, post2yr) for the BS and BFT stances. A chi-square analysis examined changes in fall risk group assignment over time. Differences between healthy controls and the LFR and HRF groups at post2yr were examined with a mixed effects model.
Findings
HFR participants showed a significant decrease in average NSI from pre-op to post1yr (p < 0.001) and post2yr (p = 0.001) for BS. BFT NSI decreased significantly from pre-op to post2yr. The chi-square test indicated a significant shift toward LFR classification at post2yr (p = 0.021). At post2yr, there were no significant NSI differences between LFR, HFR, and controls.
Interpretations
TAA improves load symmetry during quiet standing, with high fall risk participants showing the most pronounced changes, indicating the potential to reduce fall risk in post-TAA older adults.
{"title":"Bilateral balance improves in low and high fall risk groups after unilateral total ankle arthroplasty","authors":"Robyn M. Hansen , Samantha I. Weiss , Sara L. Arena , Robin M. Queen","doi":"10.1016/j.clinbiomech.2025.106719","DOIUrl":"10.1016/j.clinbiomech.2025.106719","url":null,"abstract":"<div><h3>Background</h3><div>Ankle osteoarthritis (OA) affects ∼1 % of the global population and impairs postural stability, increasing fall risk. Total ankle arthroplasty (TAA) is one of the most common surgical treatments, but balance impairments may persist post-op. The study examined differences in load symmetry across time for patients with ankle OA and post-TAA at low (LFR) or high fall risk (HFR) and then compared these groups with healthy controls.</div></div><div><h3>Methods</h3><div>All participants completed a balance assessment consisting of four static stances: shoulder width (BS), feet together (BFT), semi-tandem, and tandem. Fall risk was determined pre-operatively. Ground reaction forces were collected using force plates (AMTI, Watertown, MA) and load symmetry was calculated using the normalized symmetry index (NSI). A mixed effects model analyzed interactions between group (LFR, HFR) and time (pre-op, post1yr, post2yr) for the BS and BFT stances. A chi-square analysis examined changes in fall risk group assignment over time. Differences between healthy controls and the LFR and HRF groups at post2yr were examined with a mixed effects model.</div></div><div><h3>Findings</h3><div>HFR participants showed a significant decrease in average NSI from pre-op to post1yr (<em>p</em> < 0.001) and post2yr (<em>p</em> = 0.001) for BS. BFT NSI decreased significantly from pre-op to post2yr. The chi-square test indicated a significant shift toward LFR classification at post2yr (<em>p</em> = 0.021). At post2yr, there were no significant NSI differences between LFR, HFR, and controls.</div></div><div><h3>Interpretations</h3><div>TAA improves load symmetry during quiet standing, with high fall risk participants showing the most pronounced changes, indicating the potential to reduce fall risk in post-TAA older adults.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106719"},"PeriodicalIF":1.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623487","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 : 2025-11-21DOI: 10.1016/j.clinbiomech.2025.106718
Patrick Corrigan , Cara L. Lewis , Kerry E. Costello , Deepak Kumar , David T. Felson , Tuhina Neogi , Kathryn L. Bacon , Michael P. LaValley , Ali Guermazi , Frank Roemer , Michael C. Nevitt , Cora E. Lewis , James C. Torner , Joshua J. Stefanik
Background
It is unclear why knee osteoarthritis (KOA) progresses from a unilateral to bilateral joint disease. This study aimed to evaluate relations between vertical ground reaction forces (VGRFs) while walking and structural worsening in the unaffected limb of adults with unilateral KOA.
Methods
Discrete metrics were extracted from the unaffected limb VGRF signal while walking at a self-selected speed. Structural worsening of the unaffected knee was evaluated over 2 years with radiographs (primary) and MRIs (secondary). Logistic regression models evaluated associations between VGRF metrics and structural worsening outcomes, while adjusting for relevant covariates. Similar relations were evaluated in adults without OA in either knee to determine if VGRF metrics uniquely relate to contralateral structural worsening in adults with unilateral KOA.
Findings
In adults with unilateral KOA (n = 262), VGRFs were not associated with radiographic joint space narrowing within the tibiofemoral compartments of the unaffected knee. Additionally, VGRFs were not associated with MRI-detected cartilage loss in the medial tibiofemoral compartment. However, for the lateral tibiofemoral compartment, higher vertical loading and unloading rates were protective against cartilage loss (Odd ratios (OR) = 0.31–0.47), while larger vertical impulses and valley magnitudes were associated with increased odds of cartilage loss (OR = 2.50 and 2.26, respectively). No relations were found in adults without OA in either knee (n = 985).
Interpretation
VGRF metrics lack the ability to predict medial tibiofemoral structural worsening in knees without OA. However, vertical impulse and valley magnitude can assist with identifying contralateral knees at risk for lateral tibiofemoral cartilage loss in those with unilateral KOA.
{"title":"Relation of vertical ground reaction forces while walking to contralateral structural worsening in adults with unilateral knee osteoarthritis: the Multicenter Osteoarthritis Study","authors":"Patrick Corrigan , Cara L. Lewis , Kerry E. Costello , Deepak Kumar , David T. Felson , Tuhina Neogi , Kathryn L. Bacon , Michael P. LaValley , Ali Guermazi , Frank Roemer , Michael C. Nevitt , Cora E. Lewis , James C. Torner , Joshua J. Stefanik","doi":"10.1016/j.clinbiomech.2025.106718","DOIUrl":"10.1016/j.clinbiomech.2025.106718","url":null,"abstract":"<div><h3>Background</h3><div>It is unclear why knee osteoarthritis (KOA) progresses from a unilateral to bilateral joint disease. This study aimed to evaluate relations between vertical ground reaction forces (VGRFs) while walking and structural worsening in the unaffected limb of adults with unilateral KOA.</div></div><div><h3>Methods</h3><div>Discrete metrics were extracted from the unaffected limb VGRF signal while walking at a self-selected speed. Structural worsening of the unaffected knee was evaluated over 2 years with radiographs (primary) and MRIs (secondary). Logistic regression models evaluated associations between VGRF metrics and structural worsening outcomes, while adjusting for relevant covariates. Similar relations were evaluated in adults without OA in either knee to determine if VGRF metrics uniquely relate to contralateral structural worsening in adults with unilateral KOA.</div></div><div><h3>Findings</h3><div>In adults with unilateral KOA (<em>n</em> = 262), VGRFs were not associated with radiographic joint space narrowing within the tibiofemoral compartments of the unaffected knee. Additionally, VGRFs were not associated with MRI-detected cartilage loss in the medial tibiofemoral compartment. However, for the lateral tibiofemoral compartment, higher vertical loading and unloading rates were protective against cartilage loss (Odd ratios (OR) = 0.31–0.47), while larger vertical impulses and valley magnitudes were associated with increased odds of cartilage loss (OR = 2.50 and 2.26, respectively). No relations were found in adults without OA in either knee (<em>n</em> = 985).</div></div><div><h3>Interpretation</h3><div>VGRF metrics lack the ability to predict medial tibiofemoral structural worsening in knees without OA. However, vertical impulse and valley magnitude can assist with identifying contralateral knees at risk for lateral tibiofemoral cartilage loss in those with unilateral KOA.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"132 ","pages":"Article 106718"},"PeriodicalIF":1.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685688","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 : 2025-11-21DOI: 10.1016/j.clinbiomech.2025.106717
Wasim Awal , Randy Bindra , Giuseppe Pastore , Lawrence Baartz , Alastair Quinn , David Saxby
Background
Following ulnar shortening osteotomies, plates are often removed due to discomfort or irritation. The screw holes left after plate removal act as stress risers and predispose the bone to fracture. To our knowledge, calcium phosphate cement (CPC) is yet to be investigated for its use in reinforcing screw holes. The aim of this study was to determine if filling screw holes with CPC in a synthetic anatomical ulna model will improve its immediate mechanical strength compared to leaving screw holes unfilled.
Methods
Eighteen synthetic anatomical ulna models were randomly divided into three equal groups. The control group was left unaltered, the drilled group received six 3.5 mm screw holes, and the CPC group had the six 3.5 mm screw holes filled with CPC. All bones were subjected to torsional loading until failure. Peak torque at failure, stiffness, and energy absorption were measured.
Findings
Compared to the drilled group, the CPC group had greater peak torque, stiffness, and energy absorption. Group effects on peak torque and stiffness were moderate (eta squared = 0.12 for both) but did not reach statistical significance (p = 0.37 and 0.38, respectively). A statistically significant group effect was found for energy absorption (p < 0.001); but post-hoc analysis revealed no difference between the drilled and CPC groups.
Interpretation
Effect sizes suggest CPC may improve mechanical performance, albeit modestly. Clinicians may consider using CPC for reinforcing screw holes after plate removal in bones like the ulna when refracture is of concern.
{"title":"Evaluation of calcium phosphate bone cement in augmenting screw hole defects in the ulna: A biomechanical study","authors":"Wasim Awal , Randy Bindra , Giuseppe Pastore , Lawrence Baartz , Alastair Quinn , David Saxby","doi":"10.1016/j.clinbiomech.2025.106717","DOIUrl":"10.1016/j.clinbiomech.2025.106717","url":null,"abstract":"<div><h3>Background</h3><div>Following ulnar shortening osteotomies, plates are often removed due to discomfort or irritation. The screw holes left after plate removal act as stress risers and predispose the bone to fracture. To our knowledge, calcium phosphate cement (CPC) is yet to be investigated for its use in reinforcing screw holes. The aim of this study was to determine if filling screw holes with CPC in a synthetic anatomical ulna model will improve its immediate mechanical strength compared to leaving screw holes unfilled.</div></div><div><h3>Methods</h3><div>Eighteen synthetic anatomical ulna models were randomly divided into three equal groups. The control group was left unaltered, the drilled group received six 3.5 mm screw holes, and the CPC group had the six 3.5 mm screw holes filled with CPC. All bones were subjected to torsional loading until failure. Peak torque at failure, stiffness, and energy absorption were measured.</div></div><div><h3>Findings</h3><div>Compared to the drilled group, the CPC group had greater peak torque, stiffness, and energy absorption. Group effects on peak torque and stiffness were moderate (eta squared = 0.12 for both) but did not reach statistical significance (<em>p</em> = 0.37 and 0.38, respectively). A statistically significant group effect was found for energy absorption (<em>p</em> < 0.001); but <em>post-hoc</em> analysis revealed no difference between the drilled and CPC groups.</div></div><div><h3>Interpretation</h3><div>Effect sizes suggest CPC may improve mechanical performance, albeit modestly. Clinicians may consider using CPC for reinforcing screw holes after plate removal in bones like the ulna when refracture is of concern.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106717"},"PeriodicalIF":1.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145598043","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 : 2025-11-21DOI: 10.1016/j.clinbiomech.2025.106720
Dheeraj Jha, Anitha D Praveen, Alexander Baker, Anita Fung, Vee San Cheong, Preeti Gupta, Ecosse L Lamoureux, Namki Hong, Yumie Rhee, Vanessa Jean Wen Koh, Halldór Pálsson, William R Taylor, Angelique Wei-Ming Chan, Stephen J Ferguson, Benedikt Helgason
Background: We predicted the fracture outcomes of simulated falls from standing height using biofidelic finite element models of older adults in Singapore. We further investigated the influence of trochanteric soft tissue thickness, measured from scans and equations estimating standing trochanteric soft tissue thickness from DXA and BMI, on predicted fracture outcomes.
Methods: Biofidelic finite element models were built using DXA scans from 280 older Singaporean adults enrolled in the Targeted Assessment and Recruitment of Geriatrics for Effective Fall Prevention Treatments study. Models were created using different trochanteric soft tissue thickness: measured from 3D optical scans in standing (reference), measured from whole-body DXA, estimated from whole-body DXA, and estimated from BMI. Predicted fracture outcomes from sideways falls were compared across these models.
Findings: The number of predicted hip fractures was higher among Chinese participants compared to Indians (females: 2.4×, males: 2.3×) and Malays (females: 2.5×, males: 1.3×). Trochanteric soft tissue thickness was the dominant factor influencing impact force and force attenuation at the greater trochanter. The whole-body DXA model had a 26 % false prediction rate compared to the reference model, while the models using estimated values from whole-body DXA and BMI had false prediction rates of 1 % and 9 %, respectively.
Interpretation: Biofidelic finite element models built using image data captures population-based differences in hip fracture risk for the three main ethnic groups in Singapore. In the absence of 3D optical scans, predicting soft tissue shapes based on whole-body DXA scans, commonly available in clinical practice, yields similar fracture predictions based on simulated falls.
{"title":"Dual-energy X-ray absorptiometry based biofidelic finite element models for simulating falls to the hip: Impact of trochanteric soft tissue thickness on fracture risk.","authors":"Dheeraj Jha, Anitha D Praveen, Alexander Baker, Anita Fung, Vee San Cheong, Preeti Gupta, Ecosse L Lamoureux, Namki Hong, Yumie Rhee, Vanessa Jean Wen Koh, Halldór Pálsson, William R Taylor, Angelique Wei-Ming Chan, Stephen J Ferguson, Benedikt Helgason","doi":"10.1016/j.clinbiomech.2025.106720","DOIUrl":"https://doi.org/10.1016/j.clinbiomech.2025.106720","url":null,"abstract":"<p><strong>Background: </strong>We predicted the fracture outcomes of simulated falls from standing height using biofidelic finite element models of older adults in Singapore. We further investigated the influence of trochanteric soft tissue thickness, measured from scans and equations estimating standing trochanteric soft tissue thickness from DXA and BMI, on predicted fracture outcomes.</p><p><strong>Methods: </strong>Biofidelic finite element models were built using DXA scans from 280 older Singaporean adults enrolled in the Targeted Assessment and Recruitment of Geriatrics for Effective Fall Prevention Treatments study. Models were created using different trochanteric soft tissue thickness: measured from 3D optical scans in standing (reference), measured from whole-body DXA, estimated from whole-body DXA, and estimated from BMI. Predicted fracture outcomes from sideways falls were compared across these models.</p><p><strong>Findings: </strong>The number of predicted hip fractures was higher among Chinese participants compared to Indians (females: 2.4×, males: 2.3×) and Malays (females: 2.5×, males: 1.3×). Trochanteric soft tissue thickness was the dominant factor influencing impact force and force attenuation at the greater trochanter. The whole-body DXA model had a 26 % false prediction rate compared to the reference model, while the models using estimated values from whole-body DXA and BMI had false prediction rates of 1 % and 9 %, respectively.</p><p><strong>Interpretation: </strong>Biofidelic finite element models built using image data captures population-based differences in hip fracture risk for the three main ethnic groups in Singapore. In the absence of 3D optical scans, predicting soft tissue shapes based on whole-body DXA scans, commonly available in clinical practice, yields similar fracture predictions based on simulated falls.</p>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":" ","pages":"106720"},"PeriodicalIF":1.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145642344","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 : 2025-11-21DOI: 10.1016/j.clinbiomech.2025.106715
Eva Pröbsting , Michael Ernst , Harald Böhm , Thomas Schmalz , Veit Schopper , Barbara Pobatschnig , Malte Bellmann
Background
Accurate motion analysis of prosthetic knee joints is essential for optimizing component design, improving gait restoration, and evaluating clinical performance. Sagittal knee angles and moments are key biomechanical parameters for assessing joint function. This study determined these parameters using various gait models and validated the results against sensor data from the prosthetic knee, supporting more reliable gait analysis and potential improvements in patient outcomes.
Methods
Nineteen above-knee amputees walked at three self-selected speeds while gait was analyzed using optoelectronic cameras and force plates. Sagittal prosthetic knee moment and angle were calculated with four different models: Plug-in Gait, adapted Clinical Cleveland, 2D-model and a new 3D-model developed for analysis of transfemoral amputees. Simultaneously, prosthetic knee sensor angle and moment data were recorded.
Findings
The mean sagittal knee angle and moment waveforms from all models closely match the sensor data, reflected by low root mean square errors, with the new developed model showing the smallest values. The most precise (most often lowest reproducibility coefficient) sagittal knee angle and moment is shown with the new model. For the sagittal knee angle the highest accuracy (most often lowest mean deviation) is also determined with this model. For the knee moment, the new model, the 2D-model and Plug-in Gait equally frequently show the smallest mean deviation.
Interpretation
Relevant parameters of prosthetic knee joints can be determined using gait analysis, but not all models have the level of accuracy and precision required for evaluating prosthetic knee joints. The new model shows the most reliable data.
{"title":"Limitations of standard gait models for the precise and accurate evaluation of prosthetic knee joints regarding their functional quality, reliability, reproducibility and safety","authors":"Eva Pröbsting , Michael Ernst , Harald Böhm , Thomas Schmalz , Veit Schopper , Barbara Pobatschnig , Malte Bellmann","doi":"10.1016/j.clinbiomech.2025.106715","DOIUrl":"10.1016/j.clinbiomech.2025.106715","url":null,"abstract":"<div><h3>Background</h3><div>Accurate motion analysis of prosthetic knee joints is essential for optimizing component design, improving gait restoration, and evaluating clinical performance. Sagittal knee angles and moments are key biomechanical parameters for assessing joint function. This study determined these parameters using various gait models and validated the results against sensor data from the prosthetic knee, supporting more reliable gait analysis and potential improvements in patient outcomes.</div></div><div><h3>Methods</h3><div>Nineteen above-knee amputees walked at three self-selected speeds while gait was analyzed using optoelectronic cameras and force plates. Sagittal prosthetic knee moment and angle were calculated with four different models: Plug-in Gait, adapted Clinical Cleveland, 2D-model and a new 3D-model developed for analysis of transfemoral amputees. Simultaneously, prosthetic knee sensor angle and moment data were recorded.</div></div><div><h3>Findings</h3><div>The mean sagittal knee angle and moment waveforms from all models closely match the sensor data, reflected by low root mean square errors, with the new developed model showing the smallest values. The most precise (most often lowest reproducibility coefficient) sagittal knee angle and moment is shown with the new model. For the sagittal knee angle the highest accuracy (most often lowest mean deviation) is also determined with this model. For the knee moment, the new model, the 2D-model and Plug-in Gait equally frequently show the smallest mean deviation.</div></div><div><h3>Interpretation</h3><div>Relevant parameters of prosthetic knee joints can be determined using gait analysis, but not all models have the level of accuracy and precision required for evaluating prosthetic knee joints. The new model shows the most reliable data.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"132 ","pages":"Article 106715"},"PeriodicalIF":1.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665408","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 : 2025-11-20DOI: 10.1016/j.clinbiomech.2025.106709
Jia Qiu , Jiasheng Shao , Shenglin Li , Chenxuan Liu , Yuan Guo , Zeng Li , Jian Song
Background
The anterolateral ligament (ALL) has structural diversity and is often injured concurrently with anterior cruciate ligament (ACL) tears. At present, the effect of ALL structural diversity on combined injury and associated reconstruction remains unclear.
Methods
A finite element model of the knee joint with combined ACL-ALL injuries was established and validated against experimental data from the pig knee joints. Three distinct ALL types (I, II, and III), classified by their femoral insertion site relative to the lateral collateral ligament (LCL), were modeled. Simulations were performed under ACL-intact, ACL-injured, ACL-deficient, and ACL-reconstructed conditions during tibial loading in flexion/extension, internal/external rotation, and varus/valgus to assess kinematics and ligament stresses.
Findings
ALL function was type-dependent. Following ACL deficiency, tibial internal rotation posed the highest risk of ALL injury. During ACL-ALL reconstruction, Type III ALL most effectively enhanced internal rotation stability and reduced peak stress in the hamstring tendon graft.
Interpretation
The ALL is a key stabilizer against internal rotation. ACL failure makes internal rotation a primary mechanism for ALL injury. For reconstruction, placing the ALL femoral insertion postero-proximal to the LCL optimizes biomechanical outcomes by improving stability and load-sharing.
{"title":"Biomechanical evaluation of anterolateral ligament anatomical variants in anterior cruciate ligament-injured and reconstructed knee joints","authors":"Jia Qiu , Jiasheng Shao , Shenglin Li , Chenxuan Liu , Yuan Guo , Zeng Li , Jian Song","doi":"10.1016/j.clinbiomech.2025.106709","DOIUrl":"10.1016/j.clinbiomech.2025.106709","url":null,"abstract":"<div><h3>Background</h3><div>The anterolateral ligament (ALL) has structural diversity and is often injured concurrently with anterior cruciate ligament (ACL) tears. At present, the effect of ALL structural diversity on combined injury and associated reconstruction remains unclear.</div></div><div><h3>Methods</h3><div>A finite element model of the knee joint with combined ACL-ALL injuries was established and validated against experimental data from the pig knee joints. Three distinct ALL types (I, II, and III), classified by their femoral insertion site relative to the lateral collateral ligament (LCL), were modeled. Simulations were performed under ACL-intact, ACL-injured, ACL-deficient, and ACL-reconstructed conditions during tibial loading in flexion/extension, internal/external rotation, and varus/valgus to assess kinematics and ligament stresses.</div></div><div><h3>Findings</h3><div>ALL function was type-dependent. Following ACL deficiency, tibial internal rotation posed the highest risk of ALL injury. During ACL-ALL reconstruction, Type III ALL most effectively enhanced internal rotation stability and reduced peak stress in the hamstring tendon graft.</div></div><div><h3>Interpretation</h3><div>The ALL is a key stabilizer against internal rotation. ACL failure makes internal rotation a primary mechanism for ALL injury. For reconstruction, placing the ALL femoral insertion postero-proximal to the LCL optimizes biomechanical outcomes by improving stability and load-sharing.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106709"},"PeriodicalIF":1.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145679613","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 : 2025-11-14DOI: 10.1016/j.clinbiomech.2025.106708
Kung-Chia Li , Che-Wei Liu , Yu-Kun Xu , Chun-Ming Chen , Shang-Chih Lin
Background
Before locking interbody cementation, debris from the reamed disc should be thoroughly cleared to increase the cement volume and decrease its flow resistance to the vertebrae.
Methods
A finite element lumbosacral model was used to assess the biomechanical effects of five different disc cement sizes on disc mobility. A new reamer featuring staggered, barbed, and multilayered cutting edges, along with spiral and conical profiles, was designed and 3D-printed to enhance debris removal. Biomechanical and clinical tests were performed using synthetic and patient discs to compare the debris weights removed by the standard drill bit and the 3D-printed reamer.
Findings
Cement size significantly affected disc mobility beyond the impact of torsional factors alone. Larger cement volumes produced a more stable cage-cement foundation and reduced sagittal and coronal motions by approximately 23.8 % compared to the standard 5 mm-thick cement coverage. The average weight of synthetic disc debris removed was 926.28 ± 49.71 mg with the 3D-printed reamer versus only 63.04 ± 4.86 mg with the standard drill bit (p < 0.01). When the drill bit was withdrawn, debris easily slipped from the spiral cutting edge. In contrast, drill bits failed to retain debris effectively, whereas the reamer’s staggered and barbed features consistently hooked and removed disc material.
Interpretation
Implanting a 5 mm cage requires removing approximately 6 ml of disc material. A larger cement fill provides a more stable cage-cement interface. The 3D-printed reamer’s staggered barbs removed debris more efficiently than traditional drill bits.
{"title":"Biomechanical effects of disc cement for lumbar locking interbody cementation: Finite-element mobility analysis and debris-removing reamer design","authors":"Kung-Chia Li , Che-Wei Liu , Yu-Kun Xu , Chun-Ming Chen , Shang-Chih Lin","doi":"10.1016/j.clinbiomech.2025.106708","DOIUrl":"10.1016/j.clinbiomech.2025.106708","url":null,"abstract":"<div><h3>Background</h3><div>Before locking interbody cementation, debris from the reamed disc should be thoroughly cleared to increase the cement volume and decrease its flow resistance to the vertebrae.</div></div><div><h3>Methods</h3><div>A finite element lumbosacral model was used to assess the biomechanical effects of five different disc cement sizes on disc mobility. A new reamer featuring staggered, barbed, and multilayered cutting edges, along with spiral and conical profiles, was designed and 3D-printed to enhance debris removal. Biomechanical and clinical tests were performed using synthetic and patient discs to compare the debris weights removed by the standard drill bit and the 3D-printed reamer.</div></div><div><h3>Findings</h3><div>Cement size significantly affected disc mobility beyond the impact of torsional factors alone. Larger cement volumes produced a more stable cage-cement foundation and reduced sagittal and coronal motions by approximately 23.8 % compared to the standard 5 mm-thick cement coverage. The average weight of synthetic disc debris removed was 926.28 ± 49.71 mg with the 3D-printed reamer versus only 63.04 ± 4.86 mg with the standard drill bit (p < 0.01). When the drill bit was withdrawn, debris easily slipped from the spiral cutting edge. In contrast, drill bits failed to retain debris effectively, whereas the reamer’s staggered and barbed features consistently hooked and removed disc material.</div></div><div><h3>Interpretation</h3><div>Implanting a 5 mm cage requires removing approximately 6 ml of disc material. A larger cement fill provides a more stable cage-cement interface. The 3D-printed reamer’s staggered barbs removed debris more efficiently than traditional drill bits.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"132 ","pages":"Article 106708"},"PeriodicalIF":1.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145716672","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 : 2025-11-13DOI: 10.1016/j.clinbiomech.2025.106695
Dawson S. Sheehan , Jason P. Oliemans , Donald W. Golden , Kalinda D. Walls , Eric C. Bennett , Spencer J. Skaper , Michael J. Asmussen , Ranita H.K. Manocha , Jared R. Fletcher
Background
Individuals with hypermobile Ehlers-Danlos Syndrome (hEDS) and Hypermobility Spectrum Disorders (HSD) often experience chronic pain, muscle fatigue, and exercise intolerance, potentially due to altered muscle-tendon mechanics. This study investigated the influence of Achilles tendon (AT) compliance and plantar flexor muscle function on the metabolic cost of walking in individuals with and without HSD/hEDS.
Methods
Eleven individuals with HSD/hEDS and 11 age- and sex-matched controls completed walking trials at, below, and above their preferred walking speed. Achilles tendon stiffness, medial gastrocnemius muscle shortening, AT energy storage, pain, and lower limb electromyographic activity were evaluated during stance phase. The energy cost of walking was also computed.
Findings
The hypermobile conditions were associated with significantly lower AT stiffness, higher energy cost of walking and increased pain. Muscle fascicle shortening, shortening velocity, muscle energy cost and mechanical efficiency were similar between groups. Greater muscle activation and antagonist coactivation were observed in HSD/hEDS, particularly during early stance, likely reflecting compensatory mechanisms for joint instability.
Interpretation
Elevated cost of walking in HSD/hEDS appears driven not by increased plantar flexor work, but by a redistribution of joint work to more proximal joints. These findings suggest that altered muscle-tendon properties and neuromuscular control strategies contribute to exercise intolerance and fatigue in the Hypermobility Spectrum Disorders and hypermobile Ehlers-Danlos Syndrome.
{"title":"To what extent do the muscles and tendons influence metabolic cost and exercise tolerance in the hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorders?","authors":"Dawson S. Sheehan , Jason P. Oliemans , Donald W. Golden , Kalinda D. Walls , Eric C. Bennett , Spencer J. Skaper , Michael J. Asmussen , Ranita H.K. Manocha , Jared R. Fletcher","doi":"10.1016/j.clinbiomech.2025.106695","DOIUrl":"10.1016/j.clinbiomech.2025.106695","url":null,"abstract":"<div><h3>Background</h3><div>Individuals with hypermobile Ehlers-Danlos Syndrome (hEDS) and Hypermobility Spectrum Disorders (HSD) often experience chronic pain, muscle fatigue, and exercise intolerance, potentially due to altered muscle-tendon mechanics. This study investigated the influence of Achilles tendon (AT) compliance and plantar flexor muscle function on the metabolic cost of walking in individuals with and without HSD/hEDS.</div></div><div><h3>Methods</h3><div>Eleven individuals with HSD/hEDS and 11 age- and sex-matched controls completed walking trials at, below, and above their preferred walking speed. Achilles tendon stiffness, medial gastrocnemius muscle shortening, AT energy storage, pain, and lower limb electromyographic activity were evaluated during stance phase. The energy cost of walking was also computed.</div></div><div><h3>Findings</h3><div>The hypermobile conditions were associated with significantly lower AT stiffness, higher energy cost of walking and increased pain. Muscle fascicle shortening, shortening velocity, muscle energy cost and mechanical efficiency were similar between groups. Greater muscle activation and antagonist coactivation were observed in HSD/hEDS, particularly during early stance, likely reflecting compensatory mechanisms for joint instability.</div></div><div><h3>Interpretation</h3><div>Elevated cost of walking in HSD/hEDS appears driven not by increased plantar flexor work, but by a redistribution of joint work to more proximal joints. These findings suggest that altered muscle-tendon properties and neuromuscular control strategies contribute to exercise intolerance and fatigue in the Hypermobility Spectrum Disorders and hypermobile Ehlers-Danlos Syndrome.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106695"},"PeriodicalIF":1.4,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145551497","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 : 2025-11-13DOI: 10.1016/j.clinbiomech.2025.106684
Sara M. Magdziarz, Molly S. Pacha, David M. Williams, Ruth L. Chimenti, Jason M. Wilken
Background
Exercise-based rehabilitation is the standard conservative treatment for Achilles tendinopathy, however, symptoms often persist post-treatment. Forefoot biasing footwear may augment rehabilitation by influencing tendon loading and ankle kinematics. This study aims to determine its effect on Achilles tendon loading and ankle kinematics in individuals with Achilles tendinopathy.
Methods
Fifteen participants with chronic symptomatic midportion Achilles tendinopathy (7 female; mean(SD) age: 39.5(6.4) years) performed seven commonly prescribed activities wearing only athletic shoes and with forefoot biasing footwear, in randomized order. Activities included walking and unilateral and bilateral heel raises and hops. Kinematics and kinetics were collected using computerized motion analysis. Achilles tendon force was estimated by dividing the ankle moment by an approximated tendon moment arm. Non-parametric statistical analyses assessed differences between footwear conditions (α = 0.05).
Findings
Forefoot biasing footwear significantly increased peak ankle dorsiflexion angle (range: 1.8–5.4 degrees) in all activities except unilateral hop, while reducing peak ankle plantarflexion angle (6.2–15.5 degrees) and ankle range of motion (1.8–10.6 degrees) with moderate to large effect sizes. Achilles tendon force impulse increased significantly (12 %–87 %) with forefoot biasing footwear in the five lowest peak loading activities, with large effect sizes. Walking showed consistent significant differences in tendon loading between footwear conditions (P ≤ 0.020). No significant differences in loading were observed between conditions for bilateral hopping (P ≥ 0.078).
Interpretation
Forefoot biasing footwear can modulate ankle angles and Achilles tendon loading in individuals with midportion Achilles tendinopathy and may be useful for progressing loading prior to introducing more advanced movements.
{"title":"Impact of forefoot biasing footwear on Achilles tendon and ankle biomechanics in individuals with Achilles tendinopathy","authors":"Sara M. Magdziarz, Molly S. Pacha, David M. Williams, Ruth L. Chimenti, Jason M. Wilken","doi":"10.1016/j.clinbiomech.2025.106684","DOIUrl":"10.1016/j.clinbiomech.2025.106684","url":null,"abstract":"<div><h3>Background</h3><div>Exercise-based rehabilitation is the standard conservative treatment for Achilles tendinopathy, however, symptoms often persist post-treatment. Forefoot biasing footwear may augment rehabilitation by influencing tendon loading and ankle kinematics. This study aims to determine its effect on Achilles tendon loading and ankle kinematics in individuals with Achilles tendinopathy.</div></div><div><h3>Methods</h3><div>Fifteen participants with chronic symptomatic midportion Achilles tendinopathy (7 female; mean(SD) age: 39.5(6.4) years) performed seven commonly prescribed activities wearing only athletic shoes and with forefoot biasing footwear, in randomized order. Activities included walking and unilateral and bilateral heel raises and hops. Kinematics and kinetics were collected using computerized motion analysis. Achilles tendon force was estimated by dividing the ankle moment by an approximated tendon moment arm. Non-parametric statistical analyses assessed differences between footwear conditions (α = 0.05).</div></div><div><h3>Findings</h3><div>Forefoot biasing footwear significantly increased peak ankle dorsiflexion angle (range: 1.8–5.4 degrees) in all activities except unilateral hop, while reducing peak ankle plantarflexion angle (6.2–15.5 degrees) and ankle range of motion (1.8–10.6 degrees) with moderate to large effect sizes. Achilles tendon force impulse increased significantly (12 %–87 %) with forefoot biasing footwear in the five lowest peak loading activities, with large effect sizes. Walking showed consistent significant differences in tendon loading between footwear conditions (<em>P</em> ≤ 0.020). No significant differences in loading were observed between conditions for bilateral hopping (<em>P</em> ≥ 0.078).</div></div><div><h3>Interpretation</h3><div>Forefoot biasing footwear can modulate ankle angles and Achilles tendon loading in individuals with midportion Achilles tendinopathy and may be useful for progressing loading prior to introducing more advanced movements.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106684"},"PeriodicalIF":1.4,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145551475","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 : 2025-11-11DOI: 10.1016/j.clinbiomech.2025.106707
Thomas B. Birchmeier , Todd A. Schwartz , Alex E. Edison , Justin D. Dennis , J. Troy Blackburn , Sandra J. Shultz
Background
Altered gait biomechanics following anterior cruciate ligament reconstruction (ACLR) contribute to the 3–6 times greater risk of osteoarthritis development in this population compared to those without a knee injury. To mitigate the onset of osteoarthritis, it is necessary to understand gait recovery during the first year post-ACLR when patients have access to rehabilitative care. The purpose of this review was to compare ACLR limb gait biomechanics to the uninjured limb and healthy controls during the first year of recovery.
Methods
Online database searches of PubMed, CINAHL, Scopus, and SportDiscus were conducted from inception to January 2025. Eligibility criteria included longitudinal studies of individuals with ACL injury who underwent ACLR (≤35 years of age) with a baseline gait assessment between pre-ACLR and 6 months post-ACLR and a follow up assessment <12 months post-surgical; and cross-sectional studies that met the same criteria except for study design. Methodological quality was assessed with the Black and Downs scale. Demographic and surgical characteristics and biomechanical outcomes were extracted from each study.
Findings
Nine studies were included in the review. The ACLR limb gait biomechanics incrementally improved in the first year of recovery. However, the ACLR limb displayed smaller sagittal plane knee angles and internal moments and was underloaded in the first 50 % stance compared to the uninjured limb and healthy controls throughout the first year post-ACLR. Differences in frontal plane loading were inconsistent.
Interpretation
Aberrant gait biomechanics associated with osteoarthritis development are not resolved during the time when patients have access to care.
{"title":"Differences in gait biomechanics in the first year after anterior cruciate ligament reconstruction: A systematic review","authors":"Thomas B. Birchmeier , Todd A. Schwartz , Alex E. Edison , Justin D. Dennis , J. Troy Blackburn , Sandra J. Shultz","doi":"10.1016/j.clinbiomech.2025.106707","DOIUrl":"10.1016/j.clinbiomech.2025.106707","url":null,"abstract":"<div><h3>Background</h3><div>Altered gait biomechanics following anterior cruciate ligament reconstruction (ACLR) contribute to the 3–6 times greater risk of osteoarthritis development in this population compared to those without a knee injury. To mitigate the onset of osteoarthritis, it is necessary to understand gait recovery during the first year post-ACLR when patients have access to rehabilitative care. The purpose of this review was to compare ACLR limb gait biomechanics to the uninjured limb and healthy controls during the first year of recovery.</div></div><div><h3>Methods</h3><div>Online database searches of PubMed, CINAHL, Scopus, and SportDiscus were conducted from inception to January 2025. Eligibility criteria included longitudinal studies of individuals with ACL injury who underwent ACLR (≤35 years of age) with a baseline gait assessment between pre-ACLR and 6 months post-ACLR and a follow up assessment <12 months post-surgical; and cross-sectional studies that met the same criteria except for study design. Methodological quality was assessed with the Black and Downs scale. Demographic and surgical characteristics and biomechanical outcomes were extracted from each study.</div></div><div><h3>Findings</h3><div>Nine studies were included in the review. The ACLR limb gait biomechanics incrementally improved in the first year of recovery. However, the ACLR limb displayed smaller sagittal plane knee angles and internal moments and was underloaded in the first 50 % stance compared to the uninjured limb and healthy controls throughout the first year post-ACLR. Differences in frontal plane loading were inconsistent.</div></div><div><h3>Interpretation</h3><div>Aberrant gait biomechanics associated with osteoarthritis development are not resolved during the time when patients have access to care.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106707"},"PeriodicalIF":1.4,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145529130","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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