Pub Date : 2024-09-27DOI: 10.1016/j.jbiomech.2024.112352
Stefan Schmid, Inès Kramers-de Quervain, Walter Baumgartner
Object lifting is often categorized into squat and stoop techniques, with the former believed to protect the back by maintaining a neutral spine, and the latter considered harmful due to spinal flexion. Despite the widespread promotion of these beliefs, there is no evidence to support such dichotomy, as spinal flexion is not conclusively linked to low back pain. This study aimed to investigate intervertebral disc deformation in the lower lumbar spine during squat and stoop lifting using indwelling bone pins. Five healthy males underwent insertion of Kirschner wires into the L3, L4, and L5 spinous processes, followed by biomechanical data collection using magnetic and optical tracking systems during upright standing, isolated flexion/extension, and object lifting with both squat and stoop techniques. Except for one subject, stoop lifting resulted in up to 90 % greater disc wedging compared to squat lifting, with a significant difference at L4/L5 (p = 0.042). The anterior annulus fibrosus experienced 10 % to 40 % more compression during stoop lifting, but no significant differences were found in posterior annulus fibrosus expansion between techniques. Lever arms were about 35 % longer during stoop compared to squat lifting. These results indicate that even though stoop lifting generally led to greater disc deformation, significant deformation was also observed during squat lifting, challenging the notion of maintaining a neutral spine with this technique. Moreover, the considerable variability observed among participants raises concerns about the suitability of current one-size-fits-all lifting guidelines.
{"title":"Intervertebral disc deformation in the lower lumbar spine during object lifting measured in vivo using indwelling bone pins.","authors":"Stefan Schmid, Inès Kramers-de Quervain, Walter Baumgartner","doi":"10.1016/j.jbiomech.2024.112352","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112352","url":null,"abstract":"<p><p>Object lifting is often categorized into squat and stoop techniques, with the former believed to protect the back by maintaining a neutral spine, and the latter considered harmful due to spinal flexion. Despite the widespread promotion of these beliefs, there is no evidence to support such dichotomy, as spinal flexion is not conclusively linked to low back pain. This study aimed to investigate intervertebral disc deformation in the lower lumbar spine during squat and stoop lifting using indwelling bone pins. Five healthy males underwent insertion of Kirschner wires into the L3, L4, and L5 spinous processes, followed by biomechanical data collection using magnetic and optical tracking systems during upright standing, isolated flexion/extension, and object lifting with both squat and stoop techniques. Except for one subject, stoop lifting resulted in up to 90 % greater disc wedging compared to squat lifting, with a significant difference at L4/L5 (p = 0.042). The anterior annulus fibrosus experienced 10 % to 40 % more compression during stoop lifting, but no significant differences were found in posterior annulus fibrosus expansion between techniques. Lever arms were about 35 % longer during stoop compared to squat lifting. These results indicate that even though stoop lifting generally led to greater disc deformation, significant deformation was also observed during squat lifting, challenging the notion of maintaining a neutral spine with this technique. Moreover, the considerable variability observed among participants raises concerns about the suitability of current one-size-fits-all lifting guidelines.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365352","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 : 2024-09-26DOI: 10.1016/j.jbiomech.2024.112342
Cellular monolayers display various degrees of coordinated motion ranging from the small scale of just a few cells to large multi-cellular scales. This collective migration carries important physical cues for creating proper tissue morphology. Previous studies have demonstrated that the energetics of the epithelial monolayer show a linear variation with time in conjunction with an arrest in monolayer motion after confluency. However, little is known about how the energetics of monolayer development are affected by confined geometries. Here, we demonstrate that micropatterned epithelial monolayers display a non-linear change in energetic variables, which coincides with the large-scale coordination of migration. This non-linear scaling behavior was further seen to be associated with the biased alignment of cells and cell–cell adhesion. These findings provide a new understanding of how developing epithelia may be impacted by different conditions in vivo.
{"title":"Energetic scaling behavior of patterned epithelium","authors":"","doi":"10.1016/j.jbiomech.2024.112342","DOIUrl":"10.1016/j.jbiomech.2024.112342","url":null,"abstract":"<div><div>Cellular monolayers display various degrees of coordinated motion ranging from the small scale of just a few cells to large multi-cellular scales. This collective migration carries important physical cues for creating proper tissue morphology. Previous studies have demonstrated that the energetics of the epithelial monolayer show a linear variation with time in conjunction with an arrest in monolayer motion after confluency. However, little is known about how the energetics of monolayer development are affected by confined geometries. Here, we demonstrate that micropatterned epithelial monolayers display a non-linear change in energetic variables, which coincides with the large-scale coordination of migration. This non-linear scaling behavior was further seen to be associated with the biased alignment of cells and cell–cell adhesion. These findings provide a new understanding of how developing epithelia may be impacted by different conditions <em>in vivo</em>.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347222","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}
Collision avoidance while walking is necessary for safe living, and faster walking speeds tend to increase collision risk. However, gait termination strategies for patients with cerebral palsy (CP), from comfortable to faster speed, remain unexplored. This study aimed to analyze these strategies in children with CP compared to typically developing (TD) children at two different speeds. Study participants included 10 children with CP (mean age, 12.5; five females; mean height, 147.8 cm; mean weight, 41.7 kg) and 10 TD children (mean age, 11.4; nine females; mean height, 142.0 cm; mean weight, 38.1 kg). Effects of walking speed on spatial, force, and temporal parameters were assessed at 100 % (WS1) and 125 % (WS2) speeds of comfortable walking. The TD group exerted a more pronounced braking force at the first step after the stop line appeared on the floor until the contralateral step at both WS1 (P = 0.006) and WS2 (P = 0.019); however, the CP group exerted a more potent force after the second step (WS1: P = 0.026, WS2: P = 0.023) in the anterior-posterior (AP) direction. Additionally, an increase in the center of mass (COM)-center of pressure (COP) divergence in the AP direction (P = 0.032), which decreased in the mediolateral (ML) direction (P = 0.036) at faster walking speeds, influenced the kinetic characteristics of the CP group from WS1 to WS2. The complex adaptations, such as unique braking forces and changes in the COM-COP divergence, suggest that gait interventions should consider the distinctive forces and adopt dynamic balancing strategies to avoid collisions during walking.
{"title":"Strategies for unplanned gait termination at comfortable and fast walking speeds in children with cerebral palsy.","authors":"Minoru Kimoto, Kyoji Okada, Kazutaka Mitobe, Masachika Saito, Hitoshi Sakamoto","doi":"10.1016/j.jbiomech.2024.112349","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112349","url":null,"abstract":"<p><p>Collision avoidance while walking is necessary for safe living, and faster walking speeds tend to increase collision risk. However, gait termination strategies for patients with cerebral palsy (CP), from comfortable to faster speed, remain unexplored. This study aimed to analyze these strategies in children with CP compared to typically developing (TD) children at two different speeds. Study participants included 10 children with CP (mean age, 12.5; five females; mean height, 147.8 cm; mean weight, 41.7 kg) and 10 TD children (mean age, 11.4; nine females; mean height, 142.0 cm; mean weight, 38.1 kg). Effects of walking speed on spatial, force, and temporal parameters were assessed at 100 % (WS1) and 125 % (WS2) speeds of comfortable walking. The TD group exerted a more pronounced braking force at the first step after the stop line appeared on the floor until the contralateral step at both WS1 (P = 0.006) and WS2 (P = 0.019); however, the CP group exerted a more potent force after the second step (WS1: P = 0.026, WS2: P = 0.023) in the anterior-posterior (AP) direction. Additionally, an increase in the center of mass (COM)-center of pressure (COP) divergence in the AP direction (P = 0.032), which decreased in the mediolateral (ML) direction (P = 0.036) at faster walking speeds, influenced the kinetic characteristics of the CP group from WS1 to WS2. The complex adaptations, such as unique braking forces and changes in the COM-COP divergence, suggest that gait interventions should consider the distinctive forces and adopt dynamic balancing strategies to avoid collisions during walking.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142375436","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 : 2024-09-26DOI: 10.1016/j.jbiomech.2024.112351
J Milnes, D Kiernan
Inverse dynamic analysis is a technique used during gait analysis to estimate intersegmental forces and net joint moments. Inverse dynamic calculations are susceptible to various forms of error. One such error is force plate drift, often produced by humidity condensing within the input connectors and electronics, causing an undesired change in output over time. This can be particularly concerning for movement laboratories where inverse dynamics are considered in clinical decision-making processes. Manufacturers will provide tolerance levels for drift. However, levels of acceptable drift are rarely considered from a clinical perspective. Therefore, this study aims to establish clinically acceptable limits of force plate drift error, induced by applying systematic errors to force plate channels, on predicted lower limb joint moments during gait. Gait data of 10 children with typical development were analysed and induced errors of 0.5 N, 1 N, 1.5 N, 3 N, 6 N and 12 N were incrementally applied to the horizontal and vertical force channels. Data were recalculated for each increment and mean profiles compared to an error free mean (±1SD) band. Error was deemed clinically significant when moments fell outside the mean (±1SD) band. Induced error at 6 N and above was sufficient to cause a clinically significant change. Sagittal and coronal plane moments at the hip were most affected, followed by the knee and then the ankle. While manufacturer guidelines for acceptable drift are usually well below 6 N, care is needed when using force plates over several minutes or more as drift may eventually exceed clinically acceptable limits.
反动态分析是步态分析中用于估算节间力和净关节力矩的一种技术。逆动态计算容易出现各种形式的误差。其中一种误差是力板漂移,通常是由于输入连接器和电子元件内的湿气凝结造成的,从而导致输出随时间发生不希望的变化。对于在临床决策过程中需要考虑反向动力学的运动实验室来说,这一点尤为重要。制造商会提供漂移的容差水平。然而,临床上很少考虑可接受的漂移水平。因此,本研究旨在确定临床上可接受的力板漂移误差限值,该限值是通过将系统误差应用于力板通道,对步态过程中的下肢关节力矩进行预测而引起的。研究分析了 10 名发育典型儿童的步态数据,并在水平和垂直力通道上分别施加了 0.5 N、1 N、1.5 N、3 N、6 N 和 12 N 的诱导误差。对每个增量重新计算数据,并将平均曲线与无误差平均值(±1SD)带进行比较。当力矩超出平均值(±1SD)范围时,误差被认为具有临床意义。6 N 及以上的诱导误差足以导致临床显著变化。髋关节矢状面和冠状面力矩受影响最大,其次是膝关节,然后是踝关节。虽然制造商给出的可接受漂移值通常远低于 6 N,但在数分钟或更长时间内使用测力板时仍需谨慎,因为漂移值最终可能会超过临床可接受的范围。
{"title":"A clinical investigation of force plate drift error on predicted joint kinetics during gait.","authors":"J Milnes, D Kiernan","doi":"10.1016/j.jbiomech.2024.112351","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112351","url":null,"abstract":"<p><p>Inverse dynamic analysis is a technique used during gait analysis to estimate intersegmental forces and net joint moments. Inverse dynamic calculations are susceptible to various forms of error. One such error is force plate drift, often produced by humidity condensing within the input connectors and electronics, causing an undesired change in output over time. This can be particularly concerning for movement laboratories where inverse dynamics are considered in clinical decision-making processes. Manufacturers will provide tolerance levels for drift. However, levels of acceptable drift are rarely considered from a clinical perspective. Therefore, this study aims to establish clinically acceptable limits of force plate drift error, induced by applying systematic errors to force plate channels, on predicted lower limb joint moments during gait. Gait data of 10 children with typical development were analysed and induced errors of 0.5 N, 1 N, 1.5 N, 3 N, 6 N and 12 N were incrementally applied to the horizontal and vertical force channels. Data were recalculated for each increment and mean profiles compared to an error free mean (±1SD) band. Error was deemed clinically significant when moments fell outside the mean (±1SD) band. Induced error at 6 N and above was sufficient to cause a clinically significant change. Sagittal and coronal plane moments at the hip were most affected, followed by the knee and then the ankle. While manufacturer guidelines for acceptable drift are usually well below 6 N, care is needed when using force plates over several minutes or more as drift may eventually exceed clinically acceptable limits.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142371878","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 : 2024-09-25DOI: 10.1016/j.jbiomech.2024.112345
This systematic review with meta-analysis aimed to investigate the effects of foot orthoses (FO) application on lower limb joint angles and moments in adults with flexible flat-feet during walking. The following five databases were systematically searched from inception until March 2024: Scopus, PubMed, EMBASE, PEDro, and Cochrane Central Register of Controlled Trials (CENTRAL). Between-group standardized mean differences (SMDs) with 95% confidence intervals were computed using a random-effects model. Study heterogeneity was assessed using the I2-index. Twenty-four studies were identified and meta-analyzed. Studies were then categorized according to the applied flat-feet assessment method: (1) foot posture index (FPI-6) or clinical observation; (2) foot print arch index or radiography; (3) arch height index (including navicular drop, the arch height index, navicular height normalized to foot length [NNHT]); (4) forefoot varus method; (5) rearfoot eversion or resting calcaneal stance position (RCSP). The meta-analysis showed significant effects of FO application during walking on peak rearfoot eversion (ten studies: moderate SMDs), peak ankle dorsiflexion (five studies: small SMDs), and eversion (seven studies: moderate SMDs). This meta-analysis indicated significant effects of FO application on peak ankle eversion moment (five studies: small SMDs) and peak knee adduction moment (six studies: small SMDs). We observed greater effects of FO application on walking mechanics in the studies that used the FPI-6 method for the assessment of foot posture. Since previous research showed particularly high test–retest reliability measures for the FPI-6 method, we recommend to uniformly use this type of foot posture measure in future studies.
{"title":"Effects of foot orthoses application during walking on lower limb joint angles and moments in adults with flat Feet: A systematic review with Meta-Analysis","authors":"","doi":"10.1016/j.jbiomech.2024.112345","DOIUrl":"10.1016/j.jbiomech.2024.112345","url":null,"abstract":"<div><div>This systematic review with <em>meta</em>-analysis aimed to investigate the effects of foot orthoses (FO) application on lower limb joint angles and moments in adults with flexible flat-feet during walking. The following five databases were systematically searched from inception until March 2024: Scopus, PubMed, EMBASE, PEDro, and Cochrane Central Register of Controlled Trials (CENTRAL). Between-group standardized mean differences (SMDs) with 95% confidence intervals were computed using a random-effects model. Study heterogeneity was assessed using the I<sup>2</sup>-index. Twenty-four studies were identified and <em>meta</em>-analyzed. Studies were then categorized according to the applied flat-feet assessment method: (1) foot posture index (FPI-6) or clinical observation; (2) foot print arch index or radiography; (3) arch height index (including navicular drop, the arch height index, navicular height normalized to foot length [NNHT]); (4) forefoot varus method; (5) rearfoot eversion or resting calcaneal stance position (RCSP). The <em>meta</em>-analysis showed significant effects of FO application during walking on peak rearfoot eversion (ten studies: moderate SMDs), peak ankle dorsiflexion (five studies: small SMDs), and eversion (seven studies: moderate SMDs). This <em>meta</em>-analysis indicated significant effects of FO application on peak ankle eversion moment (five studies: small SMDs) and peak knee adduction moment (six studies: small SMDs). We observed greater effects of FO application on walking mechanics in the studies that used the FPI-6 method for the assessment of foot posture. Since previous research showed particularly high test–retest reliability measures for the FPI-6 method, we recommend to uniformly use this type of foot posture measure in future studies.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358619","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}
Pub Date : 2024-09-24DOI: 10.1016/j.jbiomech.2024.112348
Rahul Narasimhan Raghuraman, Divya Srinivasan
While back-support exoskeletons are increasing in popularity as an ergonomic intervention for manual material handling, they may cause alterations to neuromuscular control required for maintaining spinal stability. This study evaluated the effects of soft and rigid passive exoskeletons on trunk local dynamic stability and trunk-pelvis coordination. Thiry-two young (18-30 years) and old (45-60 years) men and women completed repetitive lifting and lowering tasks using two different exoskeletons and in a control condition. Both exoskeletons significantly reduced the short-term maximum Lyapunov exponent (LyE) of the trunk (p < 0.01), suggesting improved local dynamic stability. There was also a significant main effect of age (p = 0.05): older adults exhibited lower short-term LyE that young adults. Use of the soft exoskeleton significantly increased, while the rigid exoskeleton significantly decreased, long-term LyE, and these changes were more pronounced in the young group compared to the old group. Additionally, exoskeleton use resulted in significant increase (p < 0.001) of mean absolute relative phase (MARP) and deviation phase (DP) by ∼30-60 %, with greater increases due to the rigid than the soft device. Thus, trunk-pelvic coordination and coordination variability were negatively impacted by exoskeleton use. Potential reasons for these findings may include exoskeleton-induced changes in lifting strategy, reduced peak trunk flexion velocity, and cycle-to-cycle variability of trunk velocity. Furthermore, although the soft and rigid devices caused comparable changes in trunk-extensor muscle activity, they exhibited differential effects on long-term maximum Lyapunov exponents as well as trunk-pelvic coordination, indicating that exoskeleton design features can have complex effects on trunk neuromuscular control.
{"title":"The effects of soft vs. rigid back-support exoskeletons on trunk dynamic stability and trunk-pelvis coordination in young and old adults during repetitive lifting.","authors":"Rahul Narasimhan Raghuraman, Divya Srinivasan","doi":"10.1016/j.jbiomech.2024.112348","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112348","url":null,"abstract":"<p><p>While back-support exoskeletons are increasing in popularity as an ergonomic intervention for manual material handling, they may cause alterations to neuromuscular control required for maintaining spinal stability. This study evaluated the effects of soft and rigid passive exoskeletons on trunk local dynamic stability and trunk-pelvis coordination. Thiry-two young (18-30 years) and old (45-60 years) men and women completed repetitive lifting and lowering tasks using two different exoskeletons and in a control condition. Both exoskeletons significantly reduced the short-term maximum Lyapunov exponent (LyE) of the trunk (p < 0.01), suggesting improved local dynamic stability. There was also a significant main effect of age (p = 0.05): older adults exhibited lower short-term LyE that young adults. Use of the soft exoskeleton significantly increased, while the rigid exoskeleton significantly decreased, long-term LyE, and these changes were more pronounced in the young group compared to the old group. Additionally, exoskeleton use resulted in significant increase (p < 0.001) of mean absolute relative phase (MARP) and deviation phase (DP) by ∼30-60 %, with greater increases due to the rigid than the soft device. Thus, trunk-pelvic coordination and coordination variability were negatively impacted by exoskeleton use. Potential reasons for these findings may include exoskeleton-induced changes in lifting strategy, reduced peak trunk flexion velocity, and cycle-to-cycle variability of trunk velocity. Furthermore, although the soft and rigid devices caused comparable changes in trunk-extensor muscle activity, they exhibited differential effects on long-term maximum Lyapunov exponents as well as trunk-pelvic coordination, indicating that exoskeleton design features can have complex effects on trunk neuromuscular control.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365355","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 : 2024-09-24DOI: 10.1016/j.jbiomech.2024.112340
Interstitial fluid load support (FLS) is a dominant mechanism of lubrication in cartilage, producing a low friction coefficient while enhancing the tissue’s load bearing capabilities. Due to its viscosity, synovial fluid (SF) may retard loss of FLS by slowing the exudation of interstitial fluid from the cartilage. This study tested this hypothesis by comparing the stress-relaxation (SRL) response of immature bovine articular cartilage immersed either in phosphate buffered saline (PBS) or in healthy mature bovine SF, under unconfined compression (fluid exudation across cut lateral tissue boundary) and indentation testing (fluid exudation across articular surface). To investigate the influence of diffusion of SF molecular constituents into cartilage, the effect of incubation time in SF on SRL was also investigated. The SRL response in unconfined compression was not significantly different in PBS versus SF when compared directly (p = 0.98) and had a slope of = 1.00 ± 0.04 ( = 0.989 ± 0.007). Samples tested in PBS exhibited characteristic relaxation times, =42.6 ± 5.3 s and = 40.8 ± 4.7 s, that were not significantly different (p = 0.40). Incubation time of 24 h in SF resulted in no significant difference in the SRL response (p = 0.39, =1.03 ± 0.12; =0.983 ± 0.011, and = 43.4 ± 10.7 s versus = 41.5 ± 4.8 s, p = 0.59). Indentation testing showed some statistically significant, but functionally insignificant, difference in SRL responses in PBS versus SF with a slope of = 0.958 ± 0.060 ( = 0.957 ± 0.020, p = 0.029, and = 16.9 ± 2.6 s versus = 19.4 ± 3.3 s, p = 0.073). Based on these results, we reject the hypothesis that healthy SF can retard the loss of FLS in cartilage due to its viscosity.
{"title":"Synovial fluid does not retard fluid exudation during stress-relaxation of immature bovine cartilage","authors":"","doi":"10.1016/j.jbiomech.2024.112340","DOIUrl":"10.1016/j.jbiomech.2024.112340","url":null,"abstract":"<div><div>Interstitial fluid load support (FLS) is a dominant mechanism of lubrication in cartilage, producing a low friction coefficient while enhancing the tissue’s load bearing capabilities. Due to its viscosity, synovial fluid (SF) may retard loss of FLS by slowing the exudation of interstitial fluid from the cartilage. This study tested this hypothesis by comparing the stress-relaxation (SRL) response of immature bovine articular cartilage immersed either in phosphate buffered saline (PBS) or in healthy mature bovine SF, under unconfined compression (fluid exudation across cut lateral tissue boundary) and indentation testing (fluid exudation across articular surface). To investigate the influence of diffusion of SF molecular constituents into cartilage, the effect of incubation time in SF on SRL was also investigated. The SRL response in unconfined compression was not significantly different in PBS versus SF when compared directly (p = 0.98) and had a slope of<span><math><mrow><mi>m</mi></mrow></math></span> = 1.00 ± 0.04 (<span><math><mrow><msup><mrow><mi>R</mi></mrow><mn>2</mn></msup></mrow></math></span> = 0.989 ± 0.007). Samples tested in PBS exhibited characteristic relaxation times, <span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>PBS</mi></mrow></msup></mrow></math></span>=42.6 ± 5.3 s and<span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>SF</mi></mrow></msup></mrow></math></span> = 40.8 ± 4.7 s, that were not significantly different (p = 0.40). Incubation time of 24 h in SF resulted in no significant difference in the SRL response (p = 0.39, <span><math><mrow><mi>m</mi></mrow></math></span>=1.03 ± 0.12; <span><math><mrow><msup><mrow><mi>R</mi></mrow><mn>2</mn></msup></mrow></math></span>=0.983 ± 0.011, and<span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>PBS</mi></mrow></msup></mrow></math></span> = 43.4 ± 10.7 s versus<span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>SF</mi></mrow></msup></mrow></math></span> = 41.5 ± 4.8 s, p = 0.59). Indentation testing showed some statistically significant, but functionally insignificant, difference in SRL responses in PBS versus SF with a slope of<span><math><mrow><mi>m</mi></mrow></math></span> = 0.958 ± 0.060 (<span><math><mrow><msup><mrow><mi>R</mi></mrow><mn>2</mn></msup></mrow></math></span> = 0.957 ± 0.020, p = 0.029, and<span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>PBS</mi></mrow></msup></mrow></math></span> = 16.9 ± 2.6 s versus<span><math><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mi>SF</mi></mrow></msup></mrow></math></span> = 19.4 ± 3.3 s, p = 0.073). Based on these results, we reject the hypothesis that healthy SF can retard the loss of FLS in cartilage due to its viscosity.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358621","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 : 2024-09-24DOI: 10.1016/j.jbiomech.2024.112343
Ryan R Mahutga, Ruturaj M Badal, Victor H Barocas, Patrick W Alford
Damage-accumulation failure models are broadly used to examine tissue property changes caused by mechanical loading. However, damage accumulation models are purely phenomenological. The underlying justification in using this type of model is often that damage occurs to the extracellular fibers and/or cells which changes the fundamental mechanical behavior of the system. In this work, we seek to align damage accumulation models with microstructural models to predict alterations in the mechanical behavior of biological materials that arise from structural heterogeneity associated with nonuniform remodeling of tissues. Further, we seek to extend this multiscale model toward assessing catastrophic failure events such as cerebral aneurysm rupture. First, we demonstrate that a model made up of linear elastin and actin and nonlinear collagen fibers can replicate bot the pre-failure and failure tissue-scale mechanics of uniaxially-stretched cerebral aneurysms. Next, we investigate how mechanical heterogeneities, like those observed in cerebral aneurysms, influence fiber and tissue failure. Notably, we find that failure occurs and the interface between regions of high and low material stiffness, suggesting that spatial mechanical heterogeneity influences aneurysm failure behavior. This model system is a step toward linking structural changes in growth and remodeling to failure properties.
{"title":"A multiscale discrete fiber model of failure in heterogeneous tissues: Applications to remodeled cerebral aneurysms.","authors":"Ryan R Mahutga, Ruturaj M Badal, Victor H Barocas, Patrick W Alford","doi":"10.1016/j.jbiomech.2024.112343","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112343","url":null,"abstract":"<p><p>Damage-accumulation failure models are broadly used to examine tissue property changes caused by mechanical loading. However, damage accumulation models are purely phenomenological. The underlying justification in using this type of model is often that damage occurs to the extracellular fibers and/or cells which changes the fundamental mechanical behavior of the system. In this work, we seek to align damage accumulation models with microstructural models to predict alterations in the mechanical behavior of biological materials that arise from structural heterogeneity associated with nonuniform remodeling of tissues. Further, we seek to extend this multiscale model toward assessing catastrophic failure events such as cerebral aneurysm rupture. First, we demonstrate that a model made up of linear elastin and actin and nonlinear collagen fibers can replicate bot the pre-failure and failure tissue-scale mechanics of uniaxially-stretched cerebral aneurysms. Next, we investigate how mechanical heterogeneities, like those observed in cerebral aneurysms, influence fiber and tissue failure. Notably, we find that failure occurs and the interface between regions of high and low material stiffness, suggesting that spatial mechanical heterogeneity influences aneurysm failure behavior. This model system is a step toward linking structural changes in growth and remodeling to failure properties.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347221","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}
The relatively low strength of bioabsorbable screws is a critical clinical issue. A shallower thread depth will increase a screw's strength, but the pull-out strength of the screw will decrease proportionally with the thread depth. We sought to provide further clarification of the relationships between (i) the thread depth and the pull-out strength, and (ii) the minor diameter and the shearing and bending strengths in bioabsorbable screws made of uncalcined and unsintered hydroxyapatite particles and poly-L-lactide (u-HA/PLLA). Seven types (thread depth from 0.1-0.7 mm) of screws with a major diameter of 4.5 mm were manufactured. Each screw type's pull-out strength was investigated using simulated bone. A shearing test and three-point bending test were both used to measure the physical strength of the screws. We then analyzed the relationships between the mechanical findings and the thread depth. The relationship between the thread depth and the pull-out strength showed a positive biphasic linear correlation with a boundary at 0.4-mm thread depth. The relationships between the minor diameter and both the shearing and bending strengths showed positive linear correlations within the range of dimensions tested. Within the scope of this study, a 0.4-mm thread depth proved to be an appropriate value that provides sufficient pull-out strength and screw strength for u-HA/PLLA screws with a 4.5-mm major diameter.
{"title":"Investigation of the appropriate thread depth for bioabsorbable screws.","authors":"Aorigele Yu, Shinji Imade, Satoshi Furuya, Hiroshi Morii, Daishiro Oka, Koichiro Nakazawa, Kazuma Shiraishi, Toshihiko Kawamura, Yuji Uchio","doi":"10.1016/j.jbiomech.2024.112321","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112321","url":null,"abstract":"<p><p>The relatively low strength of bioabsorbable screws is a critical clinical issue. A shallower thread depth will increase a screw's strength, but the pull-out strength of the screw will decrease proportionally with the thread depth. We sought to provide further clarification of the relationships between (i) the thread depth and the pull-out strength, and (ii) the minor diameter and the shearing and bending strengths in bioabsorbable screws made of uncalcined and unsintered hydroxyapatite particles and poly-L-lactide (u-HA/PLLA). Seven types (thread depth from 0.1-0.7 mm) of screws with a major diameter of 4.5 mm were manufactured. Each screw type's pull-out strength was investigated using simulated bone. A shearing test and three-point bending test were both used to measure the physical strength of the screws. We then analyzed the relationships between the mechanical findings and the thread depth. The relationship between the thread depth and the pull-out strength showed a positive biphasic linear correlation with a boundary at 0.4-mm thread depth. The relationships between the minor diameter and both the shearing and bending strengths showed positive linear correlations within the range of dimensions tested. Within the scope of this study, a 0.4-mm thread depth proved to be an appropriate value that provides sufficient pull-out strength and screw strength for u-HA/PLLA screws with a 4.5-mm major diameter.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365353","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 : 2024-09-21DOI: 10.1016/j.jbiomech.2024.112328
Radek Vitásek, Luboš Kubíček, David Schwarz, Robert Staffa, Stanislav Polzer
The biomechanical rupture risk assessment (BRRA) of abdominal aortic aneurysms (AAA) has higher sensitivity than maximal diameter criterion (DSEX) but its estimation is time-consuming and relies on an uncertain estimation of wall thickness. The aim of this study is to test tension-based criterion in the BRRA of AAA which removes the necessity of wall thickness measurement and should be faster. For that, we retrospectively analyzed 99 patients with intact AAA (25 females). Nineteen of them experienced a rupture later. BRRA was performed with wall tension PRRIT as a primary criterion. The ability of criterion to separate intact and ruptured AAAs at 1,3,6,9 and 12 months was estimated. Next, the receiver operating characteristics and the percentage of true negative cases for a different time to an outcome were estimated. Finally, the computational time was recorded. The results were compared to stress-based criterion PRRI and DSEX which served as a reference. All three criterions were able to discriminate between intact and ruptured AAAs up to 9 months (p < 0.05) while none of them could do for a 12 month prediction. PRRIT exhibited a significantly higher percentage of true negatives for 12 and 9 month predictions (45 % and 20 % respectively) and similar to other criteria for other prediction times. The mean computational time for estimating PRRIT was 19 h per patient compared to 67 h for PRRI. The tension- based BRRA of AAA leads to better outcomes for a 9 and 12 month prediction while the computational time drops by more than 70 % compared to PRRI.
{"title":"Tension-based abdominal aortic aneurysm rupture risk assessment improves its accuracy and reduces the time of analysis.","authors":"Radek Vitásek, Luboš Kubíček, David Schwarz, Robert Staffa, Stanislav Polzer","doi":"10.1016/j.jbiomech.2024.112328","DOIUrl":"https://doi.org/10.1016/j.jbiomech.2024.112328","url":null,"abstract":"<p><p>The biomechanical rupture risk assessment (BRRA) of abdominal aortic aneurysms (AAA) has higher sensitivity than maximal diameter criterion (D<sub>SEX</sub>) but its estimation is time-consuming and relies on an uncertain estimation of wall thickness. The aim of this study is to test tension-based criterion in the BRRA of AAA which removes the necessity of wall thickness measurement and should be faster. For that, we retrospectively analyzed 99 patients with intact AAA (25 females). Nineteen of them experienced a rupture later. BRRA was performed with wall tension PRRI<sub>T</sub> as a primary criterion. The ability of criterion to separate intact and ruptured AAAs at 1,3,6,9 and 12 months was estimated. Next, the receiver operating characteristics and the percentage of true negative cases for a different time to an outcome were estimated. Finally, the computational time was recorded. The results were compared to stress-based criterion PRRI and D<sub>SEX</sub> which served as a reference. All three criterions were able to discriminate between intact and ruptured AAAs up to 9 months (p < 0.05) while none of them could do for a 12 month prediction. PRRI<sub>T</sub> exhibited a significantly higher percentage of true negatives for 12 and 9 month predictions (45 % and 20 % respectively) and similar to other criteria for other prediction times. The mean computational time for estimating PRRI<sub>T</sub> was 19 h per patient compared to 67 h for PRRI. The tension- based BRRA of AAA leads to better outcomes for a 9 and 12 month prediction while the computational time drops by more than 70 % compared to PRRI.</p>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365354","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}