Clinical Biomechanics最新文献

{"title":"Comparison of pedicle screw loosening under uniaxial and multiaxial loading","authors":"Martine McGregor ,&nbsp;Chloe Cadieux ,&nbsp;Claire Thompson ,&nbsp;Renan Fernandes ,&nbsp;Jonah Leinwand ,&nbsp;Parham Rasoulinejad ,&nbsp;Stewart McLachlin","doi":"10.1016/j.clinbiomech.2025.106692","DOIUrl":"10.1016/j.clinbiomech.2025.106692","url":null,"abstract":"<div><h3>Background</h3><div>Pedicle screw loosening is a clinically-relevant failure mode following spinal fusion procedures, resulting from damage and compaction to the surrounding bone with loading of the bone-implant interface. Current <em>in vitro</em> tests for investigating pedicle screw loosening commonly apply uniaxial loading (<em>e.g.</em> screw pullout or toggle testing). However, these methods do not replicate multiaxial spinal loading associated with activities of daily living. The goals of this study were to (1) develop and assess a novel test method for inducing pedicle screw loosening under multiaxial loading conditions, and (2) compare this approach to uniaxial toggle testing.</div></div><div><h3>Methods</h3><div>Eight osteoporotic human lumbar vertebrae (L2-L4, 70.1 ± 5.5 years old) underwent testing to compare volumetric bone damage and screw displacement under uniaxial and multiaxial loading. Load magnitudes were incrementally increased in a step-wise fashion after 1000 and 2000 cycles, with the final load step continuing until the screw head displaced more than 6 mm. Post-test computed tomography (CT) imaging was used to quantify volumetric bone damage.</div></div><div><h3>Findings</h3><div>Multiaxial loading accelerated bone damage leading to earlier implant loosening (<em>p</em> &lt; 0.001). Failure predominantly occurred in the inferior direction (<em>p</em> = 0.06). Medial (<em>p</em> = 0.07) and lateral (p &lt; 0.001) screw displacement were greater under multiaxial loading. CT imaging showed greater volumetric bone deformation with multiaxial loading (<em>p</em> = 0.01).</div></div><div><h3>Interpretation</h3><div>This study demonstrated that physiologically-derived multiaxial loading accelerates volumetric bone damage and pedicle screw loosening. Further, the increased bone deformation in the medial and lateral directions suggests that spinal movements involving these loads may accelerate risk of screw loosening.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106692"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145460286","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}

{"title":"Gait assessment of osteosarcoma patients undergoing total knee arthroplasty: Influence of abduction-adduction angles in knee prostheses","authors":"Rui Xu ,&nbsp;Shiyu Zhang ,&nbsp;Jingwen Chen ,&nbsp;Mingyong Gu ,&nbsp;Juan Du ,&nbsp;Lin Meng ,&nbsp;Jingyu Zhang ,&nbsp;Dong Ming","doi":"10.1016/j.clinbiomech.2025.106714","DOIUrl":"10.1016/j.clinbiomech.2025.106714","url":null,"abstract":"<div><h3>Background</h3><div>Bone tumors often affect the knee, necessitating total knee arthroplasty for functional restoration. While rotating hinge prostheses enable biaxial movement, an ideal design should replicate natural multi-axis motion. A proposed ball-axis prosthesis with an open coronal plane has undergone in vitro finite element validation but lacks in vivo assessment. This study aims to deeply explore the influence of abduction-adduction freedom of the open prosthesis knee joint on the gait function of patients in vivo.</div></div><div><h3>Methods</h3><div>We recruited 8 patients with ball-axis prostheses, 8 with rotating hinge knee prostheses, and 8 healthy controls to collect three-dimensional motion data and ground reaction forces during normal gait. The joint angles and moments of the lower extremities were calculated using the musculoskeletal model. The characteristic parameters of the joint angle and moment curves were calculated, and one-way analysis of variance was used to evaluate the mean differences between groups.</div></div><div><h3>Findings</h3><div>Compared to the rotating hinge prosthesis, the ball-axis prosthesis exhibited significantly lower gait speed, peak knee flexion during the swing phase, and peak anterior ground reaction force (<em>p</em> = 0.030, <em>p</em> = 0.010, <em>p</em> = 0.018). Despite the opened coronal plane freedom, there was no significant difference in gait abduction-adduction range compared to the rotating hinge prosthesis or healthy controls.</div></div><div><h3>Interpretation</h3><div>This study indicates the patients with ball-axis prosthesis had weaker propulsion and did not expand the abduction–adduction range as expected. The in vivo gait analysis of ball-axis prostheses provides a valuable reference for future prosthetic design improvements.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106714"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145607195","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}

{"title":"Comparison of prosthetic/limb alignment, soft tissue balance, and clinical outcomes between two different prostheses in ground kinematically aligned total knee arthroplasty","authors":"Tomoyuki Matsumoto ,&nbsp;Naoki Nakano ,&nbsp;Masanori Tsubosaka ,&nbsp;Kazunari Ishida ,&nbsp;Tomoyuki Kamenaga ,&nbsp;Yuichi Kuroda ,&nbsp;Shinya Hayashi ,&nbsp;Hirotsugu Muratsu ,&nbsp;Ryosuke Kuroda","doi":"10.1016/j.clinbiomech.2025.106710","DOIUrl":"10.1016/j.clinbiomech.2025.106710","url":null,"abstract":"<div><h3>Background</h3><div>Kinematically aligned total knee arthroplasty has gained popularity. This study aimed to evaluate kinematic alignment targeting the neutral ground mechanical axis (ground kinematic alignment) through a comparison between two modern prostheses.</div></div><div><h3>Methods</h3><div>This cohort study included 82 consecutive patients (46 Persona® and 36 ATTUNE® prostheses) who underwent unilateral ground kinematically aligned total knee arthroplasty using a portable navigation system for varus osteoarthritis. After 1:1 propensity score matching, 56 patients with comparable demographic data were matched between groups. Patellar orientation, hip-knee-ankle angle, coronal femoral/tibial component alignment, and joint line orientation angle were compared between the groups. Intra-operative patellar tracking and soft tissue balance, including joint component gap and varus/valgus balance, were also compared. At 1 year postoperatively, clinical outcomes, including range of motion and 2011 Knee Society Score, were compared.</div></div><div><h3>Findings</h3><div>Radiological parameters including patellar shift and tilt were not significantly different between the groups, however the ratio of intraoperative lateral retinacular release to adjust patellar tracking was significantly higher in the Persona group than in the ATTUNE group. While both groups showed similar pattern of intra-operative soft tissue balance, the ATTUNE group showed a more stable joint component gap in the shallow range of flexion and a smaller lateral laxity in deep flexion than the Persona group (<em>p</em> &lt; 0.05). There were no significant differences in clinical outcomes between the groups.</div></div><div><h3>Interpretation</h3><div>Ground kinematically aligned total knee arthroplasty using Persona or ATTUNE prostheses showed similar intra-operative and postoperative results; however, consideration should also be given to the characteristics between the models.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106710"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623488","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}

{"title":"Biomechanical evaluation of anterolateral ligament anatomical variants in anterior cruciate ligament-injured and reconstructed knee joints","authors":"Jia Qiu ,&nbsp;Jiasheng Shao ,&nbsp;Shenglin Li ,&nbsp;Chenxuan Liu ,&nbsp;Yuan Guo ,&nbsp;Zeng Li ,&nbsp;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":"2026-01-01","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}

{"title":"Discrimination of independent walking by spatiotemporal gait parameter variability in patients with hemiparesis following stroke","authors":"Taishi Kikkawa ,&nbsp;Kouta Kunitomo ,&nbsp;Tsubasa Mitsutake ,&nbsp;Takeshi Imura ,&nbsp;Ryo Tanaka","doi":"10.1016/j.clinbiomech.2025.106711","DOIUrl":"10.1016/j.clinbiomech.2025.106711","url":null,"abstract":"<div><h3>Background</h3><div>Gait variability in spatiotemporal parameters, a measure related to gait stability, is associated with fall risk in patients with stroke. Assessing gait variability may also be critical for independent walking in patients with hemiparesis following stroke. However, it remains unclear whether gait variability can discriminate between independent walking. This study aimed to evaluate the efficacy of gait variability indicators in discriminating independent walking in patients with hemiparesis following stroke.</div></div><div><h3>Methods</h3><div>This cross-sectional study included 135 patients with hemiparesis following stroke (94 training and 41 validation samples). Gait variability indicators, calculated as the coefficient of variation (CV), included stride time, step time, single support time, and step length. Independent walking was assessed using the Functional Ambulation Category (FAC) and classified into independent and non-independent groups. Discriminant performance was evaluated using the area under the receiver operating characteristic curve (AUROC) and cutoff values, analyzed separately for the training and validation samples.</div></div><div><h3>Findings</h3><div>The AUROC values for gait variability indicators were above 0.8, indicating moderate discrimination accuracy. The cutoff values were 4.32 % for stride time CV, 6.08 % for step time CV, 7.82 % for single support time CV, and 9.97 % for step length CV. The training and validation samples showed equivalent discrimination performance.</div></div><div><h3>Interpretation</h3><div>Gait variability indicators demonstrated moderate accuracy in discriminating independent walking in patients with hemiparesis following stroke. These findings highlight the effectiveness of gait stability assessment for discriminating walking independence in this population.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106711"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145662680","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}

{"title":"Biomechanical analysis of pedicle screw density and rod contouring in adolescent idiopathic scoliosis instrumentation","authors":"Alexandria Mallinos ,&nbsp;Camille Pillot ,&nbsp;Xiaoyu Wang ,&nbsp;Todd F. Ritzman ,&nbsp;Lorena V. Floccari ,&nbsp;Carl-Eric Aubin ,&nbsp;Richard M. Schwend","doi":"10.1016/j.clinbiomech.2025.106694","DOIUrl":"10.1016/j.clinbiomech.2025.106694","url":null,"abstract":"<div><h3>Background</h3><div>Pedicle screw density and rod contouring are crucial in the posterior spinal fusion (PSF) in adolescent idiopathic scoliosis (AIS) patients. This study evaluates the three-dimensional (3D) biomechanical interaction between rod contouring and the number/pattern of implants anchoring these rods to determine a range of advisable combinations that improve clinical outcomes.</div></div><div><h3>Methods</h3><div>Patient-specific, deterministic computational models were developed based on ten Lenke 1 AIS surgical cases. First order assessment with various pedicle screw patterns and rod contouring angles was performed. Rod material properties consisted of cobalt chrome (CoCr) and titanium (Ti). The primary correction maneuvers were concave rod translation followed by convex rod translation. Four screw configurations were tested: a reference pattern with two screws per level, and three alternatives (alternate, convex alternate, and convex peri-apical dropout) averaging 1.11 to 1.56 screws per level.</div></div><div><h3>Findings</h3><div>Across the four screw density patterns tested, no statistically significant differences were observed in all three anatomical planes (<em>p</em> &gt; 0.05). Significant differences in thoracic kyphosis (TK) were observed with increasing rod angulations (<em>p</em> &lt; 0.05). Coronal plane correction diminished with greater rod contouring (<em>p</em> &lt; 0.05). Axial bone-screw forces were negatively influenced by screw density and varied significantly amongst rod contouring combinations (<em>p</em> &lt; 0.05). Apical vertebral rotation (AVR) was not influenced by rod properties or screw density (<em>p</em> &gt; 0.05).</div></div><div><h3>Interpretation</h3><div>Screw density had the greatest impact on axial bone-screw forces. Regardless of the screw density pattern, more aggressive rod contouring angles reduced coronal plane correction but improved sagittal plane alignment.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106694"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145579403","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}

{"title":"Differences in gait biomechanics in the first year after anterior cruciate ligament reconstruction: A systematic review","authors":"Thomas B. Birchmeier ,&nbsp;Todd A. Schwartz ,&nbsp;Alex E. Edison ,&nbsp;Justin D. Dennis ,&nbsp;J. Troy Blackburn ,&nbsp;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 &lt;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":"2026-01-01","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}

{"title":"Free-living physical activity levels in children with cerebral palsy","authors":"Maija Piiparinen ,&nbsp;Pedro Valadão ,&nbsp;Tiina Savikangas ,&nbsp;Ying Gao ,&nbsp;Francesco Cenni ,&nbsp;Taija Finni","doi":"10.1016/j.clinbiomech.2025.106713","DOIUrl":"10.1016/j.clinbiomech.2025.106713","url":null,"abstract":"<div><h3>Background</h3><div>Cerebral Palsy (CP) is a common motor disorder in children, leading to reduced physical activity (PA) and increased health risks. To complement traditional PA methods (e.g. accelerometers, self-reports), electromyography (EMG) provides physiologically relevant information on muscle activity during free-living. This study used EMG for assessing daily muscle activity in individuals with CP and their typically developing (TD) peers.</div></div><div><h3>Methods</h3><div>Shorts with embedded EMG electrodes and hip-worn tri-axial accelerometer recorded daily PA in 8 children with spastic CP (mean age 14y 7mo, Gross Motor Function Classification System (GMFCS) I (<em>n</em> = 5), III (<em>n</em> = 3)) and 6 TD children (mean age 15y 4mo) during free-living. Daily EMG activity levels are reported as a percentage of mean EMG amplitude during the 6MWT. Inactivity time and light, moderate and vigorous PA are reported relative to recording time using established cut-off values for accelerometry, and EMG amplitude categorized based on a two-minute average from the middle of 6MWT.</div></div><div><h3>Findings</h3><div>Free-living EMG inactivity (CP: 58.4 %, TD: 50.4 %) and activity levels did not differ statistically between CP and TD groups. Accelerometry showed a greater inactivity time than EMG in CP (<em>p</em> = 0.021) and TD (<em>p</em> = 0.010) groups. In CP, few statistically significant differences were observed between legs, muscles, and GMFCS levels.</div></div><div><h3>Interpretation</h3><div>Free-living EMG monitoring did not reveal excessive muscle activity in individuals with CP during daily activities compared to TD peers. EMG detects light PA that accelerometry may underestimate, offering a more detailed view of daily muscle use.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106713"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145624302","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}

{"title":"Comparing the effect of short foot exercise and toe curl exercise on plantar pressure during single-leg standing in individuals with flatfoot: A randomized controlled trial","authors":"Misaki Suzuki ,&nbsp;Hironobu Kuruma ,&nbsp;Kunihiro Kato ,&nbsp;Hiromu Kase ,&nbsp;Hayato Fujimoto ,&nbsp;Rento Nagashima","doi":"10.1016/j.clinbiomech.2025.106693","DOIUrl":"10.1016/j.clinbiomech.2025.106693","url":null,"abstract":"<div><h3>Background</h3><div>Controlling flatfoot biomechanics is crucial in preventing lower limb musculoskeletal injuries. Short foot exercise (SFE) and toe curl exercise (TCE) are interventions for flatfoot; however, their effects on foot biomechanics remain inconsistent. We aimed to compare the impact of SFE and TCE on plantar pressure during single-leg standing (SLS) in individuals with flatfoot.</div></div><div><h3>Methods</h3><div>This randomized controlled trial recruited 34 participants with flatfoot (Foot Posture Index-6 &gt; 7). Participants were randomly assigned to SFE or TCE groups and completed 8 weeks of exercise. Plantar pressure during SLS was assessed pre- and post-intervention using a plantar pressure sensor. The foot was divided into eight regions: heel, midfoot, medial, central, lateral metatarsophalangeal joint (MTPJ), hallux, second toe, and 3rd–5th toes. Peak plantar pressure and contact area were analyzed using intention-to-treat (ITT) and per-protocol (PP) analysis.</div></div><div><h3>Findings</h3><div>In the ITT analysis, SFE significantly increased peak plantar pressure in the medial MTPJ (<em>p</em> = 0.016), hallux (<em>p</em> &lt; 0.001), and second toe (<em>p</em> = 0.004), while reducing midfoot pressure (<em>p</em> = 0.0012). TCE significantly increased the heel pressure (<em>p</em> &lt; 0.001). The PP analysis showed similar trends, with additional increases in the lateral MTPJ pressure (<em>p</em> = 0.032) and contact areas of the 3rd–5th toes (<em>p</em> = 0.008) in the SFE group.</div></div><div><h3>Interpretation</h3><div>SFE increased the medial and lateral MTPJ, hallux, and toe pressure while reducing midfoot pressure. TCE increased the heel pressure. These findings suggest that SFE improves the midfoot, medial and lateral MTPJ, and toe pressure in individuals with flatfoot.</div><div>Clinical trial registration number: UMIN000049963.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106693"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145453958","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}

{"title":"A biomechanical study comparing combined S1AI and S3AI trajectories to other pelvic fixation techniques: A finite element analysis","authors":"William Sheppard ,&nbsp;Arpan A. Patel ,&nbsp;Colin Rhoads ,&nbsp;Landon Reading ,&nbsp;Theodore Rudic ,&nbsp;Joshua Wiener ,&nbsp;Matthew Magro ,&nbsp;Lauren M. Boden ,&nbsp;Thomas Olson ,&nbsp;Jason Savage ,&nbsp;Michael Steinmetz ,&nbsp;Edin Nevzati ,&nbsp;Alexander Spiessberger","doi":"10.1016/j.clinbiomech.2025.106712","DOIUrl":"10.1016/j.clinbiomech.2025.106712","url":null,"abstract":"<div><h3>Background</h3><div>Pelvic fixation is fundamental to multi-level spinal fusion constructs. Established techniques include conventional iliac, S1-alar-iliac (S1AI), S2-alar-iliac (S2AI), and S3-alar-iliac (S3AI) fixation. Novel porous sacral-alar-iliac (SAI) screws with integrated tulips are increasingly used in long constructs requiring bilateral pelvic fixation. The optimal pelvic fixation strategy remains debated. Conventional techniques include iliac screws and sacral-alar-iliac (SAI) variants, while combined constructs such as S1AI + S3AI remain underexplored. This study presents a finite element analysis (FEA) comparing the biomechanical impact of various fixation methods, with emphasis on combined S1AI + S3AI fixation.</div></div><div><h3>Methods</h3><div>Six L1–pelvis FEA models were created: one noninstrumented control (V1) and five instrumented variants—iliac screw (V2), S1AI (V3), S2AI (V4), 8.5 mm S1AI + S3AI (V5), and 10.5 mm S1AI + S3AI (V6). L5-S1 interbody fusion was modelled in all constructs. Loading conditions included flexion, axial-compression, and lateral bending at 100 N, 200 N, and 300 N. Von Mises Stress (VMS) and range of motion (ROM) were analyzed.</div></div><div><h3>Findings</h3><div>All instrumented constructs reduced ROM versus control. V3 had the lowest ROM but showed construct imbalances internally, cranial to caudal. V6 offered the most uniform ROM reduction. V5 and V6 exhibited the lowest pelvic VMS; V2–V4 had higher stress than control. Instrumentation stress localized to L5-S1 in all variants, with V3 showing bilateral S1AI instrumentation stress. V5 and V6 demonstrated the most favorable stress profiles throughout.</div></div><div><h3>Interpretation</h3><div>Combined S1AI + S3AI fixation outperformed other pelvic constructs biomechanically, with reduced stress and improved ROM distribution. These findings support its use in long spinal fusions to enhance construct durability and may help guide surgical decision-making. Additional, clinical studies are needed to validate these findings.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"131 ","pages":"Article 106712"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145607184","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}