Clinical Biomechanics最新文献

{"title":"Phase-specific changes in hip joint loading during gait following sacroiliac joint fusion: Findings from a finite element analysis","authors":"Yogesh Kumaran ,&nbsp;Janice M. Bonsu ,&nbsp;Sudharshan Tripathi ,&nbsp;Sophia M. Soehnlen ,&nbsp;Carmen E. Quatman","doi":"10.1016/j.clinbiomech.2025.106429","DOIUrl":"10.1016/j.clinbiomech.2025.106429","url":null,"abstract":"<div><h3>Background</h3><div>Low back pain affects over 80 % of adults, with sacroiliac joint dysfunction accounting for 15–30 % of these cases. Sacroiliac fusion is a surgical procedure for refractory joint pain. While the biomechanics of the joint and its fusion relative to the spinal column are well-known, the hip-spine relationship post-fusion remains unclear. Understanding the biomechanical state following fusion can enhance patient recovery and optimize surgical outcomes. This study uses finite element analysis to assess hip joint biomechanics following sacroiliac joint fusion.</div></div><div><h3>Methods</h3><div>CTs of a 55-year-old male were used to create a biomechanical model, validated against a cadaveric study. Three triangular titanium alloy implants were placed across the sacroiliac joint in a unilateral and bilateral configuration. The model, loaded with pelvis and hip joint kinematics during a gait cycle, calculated joint reaction forces, contact stress and area on the hip joint across various gait phases.</div></div><div><h3>Findings</h3><div>Hip joint contact stresses varied with fixation configurations and gait phases. Unilateral right fusion reduced joint reaction forces by 2 % but increased contact stress by 3.7 %. Bilateral fusion increased joint reaction forces by 6.7 % and contact stress by 3.25 %, with higher stress during foot flat and heel off phases compared to unilateral fixation.</div></div><div><h3>Interpretation</h3><div>Fusion alters hip loading patterns during specific gait phases, with bilateral fusion producing the highest stresses during foot flat and heel off. These findings may suggest the need for fusion-specific rehabilitation protocols and warrants further investigation of long-term joint health outcomes.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106429"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142973113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influences of upper limb orthosis on trunk muscle activity during static and dynamic sitting tasks for hemiparetic stroke","authors":"Kazuhiro Fukata ,&nbsp;Yuya Chiba ,&nbsp;Kohei Shida ,&nbsp;Saki Natsuaki ,&nbsp;Ryota Kakinuma ,&nbsp;Natsumi Izumi ,&nbsp;Kazu Amimoto ,&nbsp;Shigeru Makita ,&nbsp;Hidetoshi Takahashi","doi":"10.1016/j.clinbiomech.2025.106439","DOIUrl":"10.1016/j.clinbiomech.2025.106439","url":null,"abstract":"<div><h3>Background</h3><div>We aimed to clarify the immediate effect of wearing the Omo Neurexa upper limb suspended orthosis (Ottobock Japan, Tokyo, Japan) on trunk muscle activity during seated tasks.</div></div><div><h3>Methods</h3><div>Fifteen participants with upper limb hemiparesis were included. Surface electromyography of the thoracic and lumbar erector spinae and the external oblique muscles was performed. All participants performed static sitting, repetitive lateral reaching, and maximum lateral reaching tasks with or without the orthosis. The paired <em>t</em>-test was performed to compare the trunk muscle activity with and without the orthosis.</div></div><div><h3>Findings</h3><div>During static sitting, the activity of the thoracic and lumbar erector spinae muscles on the non-paretic side was significantly greater with the orthosis than without it (<em>p</em> = 0.025 and <em>p</em> = 0.047, respectively). The time required to complete five repetitive lateral reaching was significantly shorter with the orthosis than without it (<em>p</em> <em>=</em> 0.030). However, the orthosis did not affect during f repetitive lateral reaching and maximum lateral reaching task.</div></div><div><h3>Interpretation</h3><div>The upper limb orthosis may influence the activity of the trunk muscles of patients who had had a stroke during static sitting and improve the sitting reaching performance. Our results suggest that the effects of upper limb orthoses on trunk muscle and sitting performance should be further explored for the treatment of sitting disabilities after hemiparetic stroke. (University Hospital Medical Information Network Clinical Trials Registry number: UMIN 000044629).</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106439"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143054186","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":"Effects of various modes of forward and backward cycling on neuro-biomechanical outcomes in individuals after stroke and healthy controls","authors":"J. Soulard ,&nbsp;C. Duclos ,&nbsp;R. Walha ,&nbsp;D. Kairy ,&nbsp;S. Nadeau","doi":"10.1016/j.clinbiomech.2025.106435","DOIUrl":"10.1016/j.clinbiomech.2025.106435","url":null,"abstract":"<div><h3>Background</h3><div>Stationary cycling is recommended for post-stroke rehabilitation. This study assessed neuro-biomechanical outcomes of forward and backward cycling in three different modes: free-pedalling, constant speed (30 RPM) and constant resistance (5 or 10 Nm) in healthy controls and individuals after stroke.</div></div><div><h3>Methods</h3><div>Ten individuals after stroke and 10 healthy controls performed 60s cycling trials in different directions and modes on a semi-recumbent bike prototype. Cycling performance (speed, torque, coefficient of variation) and the activity of the non-dominant limb muscles (rectus femoris, vastus lateralis, tensor fascia latae, and biceps femoris) were collected.</div></div><div><h3>Findings</h3><div>Cycling performance was lower in backward than forward direction in both groups, but to a greater extent in individuals after stroke. Variability was reduced in backward compared to forward pedalling except for free-pedalling. At constant speed, both groups showed similar increase in rectus femoris activation during the propulsive phase of backward cycling while an increase was only observed in the stroke group for the tensor fascia latae. The constant resistance mode revealed more difference between groups: individuals after stroke showed changes of rectus femoris and vastus lateralis activation with pedalling direction in both phases while healthy controls had changes only in the vastus lateralis. Tensor fascia latae activation differed between groups but was not affected by direction. The biceps femoris activation was more variable.</div></div><div><h3>Interpretation</h3><div>Various cycling directions and modes influenced neuro-biomechanical outcomes, even more in individuals after stroke. Future research should determine how they could enhance functional abilities after stroke when used during rehabilitation.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106435"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143030242","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":"An investigation of the mechanism of adjacent segment disease in a porcine spine model","authors":"Noah Chow ,&nbsp;Sabrina I. Sinopoli ,&nbsp;Mitchel C. Whittal ,&nbsp;Drew A. Bednar ,&nbsp;Diane E. Gregory","doi":"10.1016/j.clinbiomech.2025.106441","DOIUrl":"10.1016/j.clinbiomech.2025.106441","url":null,"abstract":"<div><h3>Background</h3><div>Fusion changes the biomechanics of the spine leading to the potential development of adjacent segment disease. Despite many studies on adjacent segment disease, it is largely unknown how spinal fixation affects the mechanical properties of the adjacent disc. The purpose of this study was to assess whether axial compression causes mechanical disruption to the annulus when the caudal spinal level is immobilized or injured.</div></div><div><h3>Methods</h3><div>Fifty-two porcine spines were assigned to one of four conditions: 1) control; 2) injured (18.5-gauge needle inserted into the nucleus of cervical 4/5); 3) immobilized (18-gauge steel wire wrapped around the transverse and spinous processes of cervical 4/5); and 4) injured+immobilized. Each specimen was then subjected to 0.5 Hz cyclic compression (300−1200N) for two hours. Post-compression, three annular samples were dissected from the cervical 3/4 disc (<strong><em>adjacent</em></strong> to immobilized and/or injured level) and mechanically tested. The same loading protocol and annular testing was also conducted in eight human cadaveric lumbar spines.</div></div><div><h3>Findings</h3><div>Immobilization and injury resulted in a reduction in <strong><em>adjacent</em></strong> disc lamellar strength including toe region stress (<em>p</em> &lt; 0.001), initial failure stress (<em>p</em> = 0.03), and ultimate stress (<em>p</em> = 0.004), with immobilization having the greatest impact. Similar findings were observed in the human cadaver samples with reduced toe region strength in the injured+ immobilized samples compared to the control (<em>p</em> = 0.049).</div></div><div><h3>Interpretation</h3><div>The current study provides empirical evidence of decreased lamellar strength in the disc adjacent to an immobilized and/or injured level following prolonged cyclic axial loading, lending mechanistic insight into the development of adjacent segment disease.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106441"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143069370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of prosthetic foot selection on walking performance during various load carriage conditions","authors":"Krista M. Cyr ,&nbsp;Richard R. Neptune ,&nbsp;Glenn K. Klute","doi":"10.1016/j.clinbiomech.2025.106440","DOIUrl":"10.1016/j.clinbiomech.2025.106440","url":null,"abstract":"<div><h3>Background</h3><div>Ambulatory individuals with lower limb amputations often face challenges with body support, body propulsion, and balance control. Carrying an infant, toddler, backpack, or other load can exacerbate these challenges and highlights the importance of prescribing the most suitable prosthetic foot. The aim of this study was to examine the influence of five different prosthetic feet on walking performance during various load carriage conditions.</div></div><div><h3>Methods</h3><div>Biomechanical data were collected from twelve participants wearing five different prosthetic feet (four passive, one powered) while walking with no added load and carrying a load of 13.6 kg in four different positions: posterior, anterior, prosthetic side, and intact side.</div></div><div><h3>Findings</h3><div>Based on our study population, a powered-ankle-foot offers additional body support when a load is carried posteriorly. If additional forward propulsion is needed while carrying a load anteriorly, a heel wedge is better than a stiffer foot. For individuals who may need additional sagittal plane balance control, no study foot was advantageous regardless of how the load was carried. For those who need additional frontal plane balance control during posterior load carriage, a heel wedge is better than a stiffer or powered foot. Lastly, the standard-of-care, heel wedge, and dual keel feet provided more frontal plane balance control than a powered foot when a load was carried anteriorly.</div></div><div><h3>Interpretation</h3><div>For individuals with lower limb amputation who carry loads, consideration of their preferred load carrying method may help select an appropriate prosthetic foot for body support, propulsion, and balance control.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106440"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143043269","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 analysis of four medial patellofemoral ligament reconstruction techniques","authors":"Thomas A. Bedard,&nbsp;Christopher K. Johnson,&nbsp;Richard L. Amendola,&nbsp;Matthew G. Scuderi,&nbsp;Nathaniel R. Ordway,&nbsp;Frederick W. Werner,&nbsp;John P. Cannizzaro","doi":"10.1016/j.clinbiomech.2024.106401","DOIUrl":"10.1016/j.clinbiomech.2024.106401","url":null,"abstract":"<div><h3>Background</h3><div>Implant free medial patellofemoral ligament reconstruction is an increasingly popular technique to address patellar instability. There remains sparse literature on the biomechanical differences between the most common femoral attachment fixation points including Schottle's point, superficial medial collateral ligament, and adductor magnus tendon. This study compared these reconstruction techniques as well as a novel triangle reconstruction integrating both superficial medial collateral ligament and adductor magnus tendon.</div></div><div><h3>Methods</h3><div>Eight cadaveric knees were tested in a muscle activated knee simulator which mimicked a standing, shallow knee bend movement. Patella lateral displacement, external rotation and flexion were measured with and without a lateral load applied under the following conditions: 1) intact, 2) medial patellofemoral ligament cut, 3) Schottle's point reconstruction, 4) adductor magnus tendon reconstruction, 5) superficial medial collateral ligament reconstruction, 6) triangle reconstruction. Differences were analyzed using a repeated measures analysis of variance at 20, 30, 45 and 60 degrees of knee flexion.</div></div><div><h3>Findings</h3><div>All reconstruction techniques had significantly less lateral displacement compared to the cut condition when a lateral load was applied. Between reconstruction conditions, there was significantly less lateral displacement using Schottle's point and superficial medial collateral ligament as compared to adductor magnus tendon (<em>p</em> &lt; 0.05). All reconstruction techniques had a trend towards medial constraint as compared to intact.</div></div><div><h3>Interpretation</h3><div>An over constrained position of the patella through early flexion of the knee may increase the likelihood of secondary patellofemoral arthritis. Although there were differences in magnitude of displacement/constraint, further studies are needed to assess clinical differences regarding constraint.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106401"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142792277","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":"Viscoelastic properties of superficial back muscles in adolescents with Lenke Type 1A and 1B idiopathic scoliosis","authors":"Burcu Şenol Gökalp ,&nbsp;Ezgi Tarhan Altınok ,&nbsp;Gözde Yağcı ,&nbsp;Özgün Uysal ,&nbsp;Fatih Erbahçeci","doi":"10.1016/j.clinbiomech.2024.106421","DOIUrl":"10.1016/j.clinbiomech.2024.106421","url":null,"abstract":"<div><h3>Background</h3><div>In this study, we aimed to evaluate the viscoelastic properties of the superficial back muscles of adolescent idiopathic scoliosis patients with Lenke Type 1A and 1B curves compared to their healthy peers.</div></div><div><h3>Methods</h3><div>20 participants with adolescent idiopathic scoliosis and 20 healthy peers were evaluated. Cobb angle was recorded for scoliosis participants. The upper, middle, and lower trapezius muscles, and latissimus dorsi muscles were evaluated bilaterally with Myoton-3 as stiffness, elasticity and tone parameters for all participants.</div></div><div><h3>Findings</h3><div>Cobb angle was 20.30 ± 8.52° for participants with adolescent idiopathic scoliosis. Muscular stiffness in participants with scoliosis was greater than that of the healthy group for all muscles and both sides. Muscle elasticity was only different for the latissimus dorsi and middle trapezius muscles for the left side and they showed significantly decrease in participants with scoliosis. There was no statistical difference in muscle tone between the groups (<em>p</em> &gt; 0.05).</div></div><div><h3>Interpretation</h3><div>Our findings suggest that adolescents with idiopathic scoliosis exhibit increased muscular stiffness bilaterally in superficial back muscles, decreased muscle elasticity on the concave side of the curve compared to healthy peers suggests potential implications for the biomechanics and rehabilitation of adolescent idiopathic scoliosis.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106421"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911105","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":"Ergometer for physical conditioning assessment of people with disabilities and parathletes","authors":"Sérgio Augusto Albino Vieira ,&nbsp;Silvio Soares dos Santos ,&nbsp;Fernando Roberto de Fazzio ,&nbsp;Roberto Mendes Finzi Neto ,&nbsp;Cleudmar Amaral de Araújo","doi":"10.1016/j.clinbiomech.2025.106434","DOIUrl":"10.1016/j.clinbiomech.2025.106434","url":null,"abstract":"<div><h3>Background</h3><div>Wheelchair users face various health issues, such as cardiac problems, obesity, tissue deformation, and shoulder and wrist injuries. Although the subject of ergometry is known since 1912 and the mechanic of propulsion gesture and wheelchair configuration has been studied over the years, most of the equipment found in the literature are adaptations or lack the tools for standardization of techniques. This paper aims to conduct biomechanical validation of a new wheelchair ergometer (ERGO1) designed for assessing physical fitness and muscle training of the upper limbs of people with disabilities.</div></div><div><h3>Methods</h3><div>ERGO1 features modular design, allowing adjustments for seat and backrest, with flywheel-equipped propulsion rims simulating ground propulsion. An electromagnetic system controlled by dedicated hardware and software provides resistance, enabling Wingate and incremental protocols. The tests used the Wingate protocol, and one study was compared to the BRUCE protocol for equivalence of electrocardiogram signals.</div></div><div><h3>Findings</h3><div>Ten volunteers underwent the first set of Wingate tests, presenting expected power and fatigue patterns for the loss of physical capacity during exercise. 23 volunteers underwent the test comparing the ERGO1 with a conventional treadmill and the correlation between the ST Segment's behavior was found.</div></div><div><h3>Interpretation</h3><div>ERGO1 is suitable for assessing physical conditioning and enables cardiovascular assessment due to the equivalency to the standard treadmill test. Costs for the systems range from 10 to 27 times less than current commercial options. It obtained a patent in 2022, and ongoing development includes adding more ergonomic adjustments and exploring virtual reality as a serious game to enhance motivation and concentration.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106434"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143015759","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":"Kinematic analysis of upper limb fractures: Insights for rehabilitation strategies","authors":"Felipe de Souza Serenza ,&nbsp;Marília Manuella Simões Augusto Rizzato ,&nbsp;Fernando Vieira ,&nbsp;Kevin James McQuade ,&nbsp;Anamaria Siriani de Oliveira","doi":"10.1016/j.clinbiomech.2025.106432","DOIUrl":"10.1016/j.clinbiomech.2025.106432","url":null,"abstract":"<div><h3>Background</h3><div>Upper limb fractures significantly alter movement, impacting function and recovery. Three-dimensional motion analysis allows precise assessment of these changes.</div></div><div><h3>Methods</h3><div>Sixty patients were divided into four groups: shoulder, elbow, wrist fractures, and controls. Functional assessment was performed using the DASH questionnaire, followed by three-dimensional kinematic analysis with eight Oqus 300 cameras and 14 reflective markers on the thorax, scapula, humerus, forearm, and hand. The Acromion Marker Cluster method was used for accurate scapular tracking. Tasks analyzed included hand on shoulder, hand on back, and hand on neck. All measured variables are expressed in degrees. The analysis focused on the differences in maximum joint angles for each degree of freedom across the tasks. These differences were assessed using MANOVA, followed by ANOVAs and Tukey's post hoc test when applicable.</div></div><div><h3>Findings</h3><div>Significant kinematic differences were observed between the fracture groups and the control group across all tasks. Shoulder fracture patients exhibited the greatest reductions in humeral flexion and abduction. Elbow fracture patients showed the most restricted elbow flexion. Wrist fracture patients presented significantly reduced radial/ulnar deviation. These movement impairments were observed across all tasks, with the most pronounced limitations seen in the hand-to-shoulder task. Effect sizes (η²) indicated clinically meaningful impacts, particularly for shoulder and wrist movements.</div></div><div><h3>Interpretation</h3><div>This study reveals distinct kinematic alterations following upper limb osteosynthesis, emphasizing the need for individualized rehabilitation strategies addressing these specific movement impairments to optimize recovery.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106432"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143015764","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":"Two minutes is sufficient to characterize the viscoelastic properties of the human lower birth canal during the first stage of labor","authors":"Mariana Masteling ,&nbsp;John O.L. DeLancey ,&nbsp;James A. Ashton-Miller","doi":"10.1016/j.clinbiomech.2025.106430","DOIUrl":"10.1016/j.clinbiomech.2025.106430","url":null,"abstract":"<div><h3>Background</h3><div>The lower birth canal is the final constriction through which a fetal head must pass for delivery. Unfortunately, injuries to the lower birth canal tissues occur in up to 19 % of first-time vaginal deliveries due to the 300 % stretch required.</div></div><div><h3>Methods</h3><div>This is a secondary analysis of data from 56 healthy nullipara recorded by a lower birth canal dilator during the first stage of labor. A four parameter Fractional Zener rheological Model was used to characterize the canal viscoelastic properties during the first stage of labor. We tested the (null) hypothesis that the Model constants identified during the initial 20 s ramp-and-5-min-hold dilation from 40 to 55 mm will not accurately predict the final hoop tension after 60 min of slower dilation.</div></div><div><h3>Findings</h3><div>The null hypothesis was rejected in that when the four Model parameters were calculated for all nullipara from the 20-s-ramp-and-5-min-hold data, the relative fit error was 8 ± 4 %, and the relative prediction error after 60 min of dilation was 10 ± 5 %. Furthermore, when the Model constants were instead calculated from the 20 s ramp and only the initial 90 s of the 5-min-hold, the error was still acceptable: 13 ± 4 % for relative fit and 13 ± 18 % for relative prediction.</div></div><div><h3>Interpretation</h3><div>Two minutes is sufficient to characterize canal viscoelastic properties during the first stage of labor and identify those with stiffer tissues at higher risk for a pelvic floor injury during delivery. This could form the basis for a clinical test predicting injury.</div></div>","PeriodicalId":50992,"journal":{"name":"Clinical Biomechanics","volume":"122 ","pages":"Article 106430"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143015788","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}