有限元法生物力学分析在青少年特发性脊柱侧凸治疗及病因研究中的应用

青少年特发性脊柱侧凸发病率较高且病情复杂,对青少年身心健康可造成显著影响,但其因病因不明,临床尚未形成治疗共识。近年来基于患者医学影像进行仿真建模的有限元法生物力学分析在青少年特发性脊柱侧凸治疗及其病因研究中已经有了一系列的应用。本文即从非手术治疗、手术治疗、病因研究、现有局限等角度对有限元法生物力学分析在青少年特发性脊柱侧凸中的应用进行综述,以期为临床实践及相关研究提供参考。     

外柱细胞软化对Corti器感音影响的生物力学研究

Corti器的感音过程容易受到内部结构属性变化的影响。外柱细胞血管舒张刺激磷蛋白缺失会减缓肌动蛋白丝的形成,从而产生听力延迟。本研究运用COMSOL建立三维有限元模型研究肌动蛋白缺失导致外柱细胞软化时,Corti器感音过程中基底膜和外毛细胞与Deiters细胞结合点的力学行为变化。结果表明,外柱细胞软化会削弱外毛细胞主动力对基底膜位移增益的放大作用,但削弱作用并不会立即产生,Corti器存在维持正常功能的"缓冲"阶段。在100 dB和120 dB之间可能存在一个声压级临界值,在该临界值两侧外柱细胞软化对基底膜应力变化的影响是截然相反的。另外外柱细胞软化对不同外毛细胞与Deiters细胞结合点力学行为的影响也不同,位移增益优先级会因此产生改变。     

Magnetic resonance elastography with guided pressure waves

Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.     

伸筋易骨法调节兔膝关节周围软组织张力影响软骨形态的研究

[目的] 评价伸筋易骨法对膝关节周围软组织张力及软骨形态的影响，以探讨其对膝关节骨性关节炎（KOA）的治疗作用。[方法] 选择6~8月龄雌性健康新西兰大耳白兔50只，随机分为5组。其中模型组、推拿组、玻璃酸钠组采用Hulth造模法模拟KOA，正常组、假手术组不做干预。造模成功后，推拿组予伸筋易骨法治疗3周，玻璃酸钠组予局部关节内注射每周1次，共3周，模型组不予任何治疗。治疗结束后，测试股直肌、股二头肌张力，并取软骨组织进行HE染色后光镜下进行形态学观察，并进行Markin评分。分析推拿组与其余4组的异同。[结果] 模型组较正常组，股直肌FDD值和S值显著降低（P<0.05），股二头肌FDD值和S值显著升高（P<0.05）。推拿组和玻璃酸钠组相较于模型组的股直肌FDD值和S值均显著升高（P<0.05））；推拿组和玻璃酸钠组相较于模型组股二头肌的FDD值和S值均显著降低（P<0.05）。推拿组和玻璃酸钠组相较于模型组，Mankin’s评分比较有统计学意义（P<0.05）。[结论] 伸筋易骨法可以显著增加关节周围肌肉的肌力、调节组织张力、改善关节活动功能，对保护膝关节周围软组织功能具有重要意义。     

Rate of torque development is the primary contributor to quadriceps avoidance gait following total knee arthroplasty

BackgroundFollowing rehabilitation for total knee arthroplasty, “quadriceps avoidance gait”, defined by limited knee flexion angle excursion during walking, persists and contributes to poor long-term outcomes. Given the presence of several post-surgical impairments, identifying the contribution of multiple factors to knee flexion angle excursion is important to developing targeted interventions to improve recovery after total knee arthroplasty.Research questionsWhich outcomes continue to improve following rehabilitation for total knee arthroplasty? What are the primary contributors to impaired knee flexion angle excursion during walking following total knee arthroplasty?MethodsPeak muscle strength and rate of torque development of the quadriceps, hip abductors, and hip external rotators, five-time sit-to-stand test, Knee Injury & Osteoarthritis Outcome Score, and gait mechanics were assessed in 24 participants at three and six months post-surgery. Paired sample t-tests or Wilcoxon Signed-Rank tests were used to compare outcomes between assessments. Stepwise multiple linear regression were used to assess the contribution of each measure to knee flexion angle excursion.ResultsSignificant improvements were noted in all outcomes except hip external rotation rate of torque development, gait speed, and knee flexion angle excursion. Quadriceps rate of torque development and knee pain significantly contributed to knee flexion angle excursion at three months (Adjusted R² = 0.342), while quadriceps rate of torque development and peak hip external rotation strength significantly contributed at six months (Adjusted R² = 0.436).SignificanceWhile higher pain levels at three months and greater peak hip external rotation muscle strength at six months contribute to impaired knee flexion angle excursion, quadriceps rate of torque development was the primary contributor to knee flexion angle excursion at both three and six months after surgery. Implementing strategies to maximize quadriceps rate of torque development during rehabilitation may help to reduce quadriceps avoidance gait after total knee arthroplasty.     

长眼轴患者白内障超声乳化术后角膜生物力学的变化

目的　观察长眼轴患者行白内障超声乳化术后角膜生物力学的变化。方法　收集拟接受白内障手术的患者58例68眼，将其分为长眼轴组（28例34眼）和正常眼轴组（30例34眼），应用可视化角膜生物力学分析仪（corneal visualization scheimpflug technology，Corvis ST）对患者术前及术后1周、1个月的角膜生物力学参数进行测量。结果　术前及术后1周、1个月两组峰距、中央角膜厚度、矫正眼压、眼压及长眼轴组第二压平时间和最大形变幅度的总体比较，差异均有统计学意义（均为P＜0.05）；术后1周与术前相比，两组峰距、中央角膜厚度、矫正眼压、眼压明显增大，长眼轴组最大形变幅度较术前减小，差异均有统计学意义（均为P＜0.05），但术后1个月正常眼轴组峰距、中央角膜厚度、矫正眼压、眼压均恢复到术前水平（均为P＞0.05），而长眼轴组最大形变幅度较术前减小，矫正眼压、眼压较术前均增高（均为P＜0.05）。术后1个月与术后1周比较，两组峰距、中央角膜厚度、矫正眼压、眼压均有减小趋势（均为P＜0.05）。长眼轴组术后1周中央角膜厚度、矫正眼压及最大形变幅度的变化量与眼轴长度均存在正相关性（r=0.493，P=0.003；r=0.575，P＜0.001；r=0.587，P＜0.001），而正常眼轴组的相关参数的变化量与眼轴长度均无相关性（均为P＞0.05）。结论　白内障超声乳化术能影响角膜生物力学，且长眼轴患者较正常眼轴者术后更易引起角膜生物力学改变，在白内障术后应注意其用药时间及激素类药物的使用，防止伤口愈合不良导致迁延感染及高眼压的发生。     

A Biomechanical Foot-Worn Device Improves Total Knee Arthroplasty Outcomes

Background

Biomechanics after total knee arthroplasty (TKA) often remain abnormal and may lead to prolonged postoperative recovery. The purpose of this study is to assess a biomechanical therapy after TKA.

Partial medial meniscectomy leads to altered walking mechanics two years after anterior cruciate ligament reconstruction: Meniscal repair does not

BackgroundPartial meniscectomy dramatically increases the risk for post-traumatic, tibiofemoral osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Concomitant medial meniscus surgery influences walking biomechanics (e.g., medial tibiofemoral joint loading) early after ACLR; whether medial meniscus surgery continues to influence walking biomechanics two years after ACLR is unknown.Research questionDoes medial meniscus treatment at the time of ACLR influence walking biomechanics two years after surgery?MethodsThis is a secondary analysis of prospectively collected data from a clinical trial (NCT01773317). Fifty-six athletes (age 24 ± 8 years) with operative reports, two-year biomechanical analyses, and no second injury prior to two-year testing participated after primary ACLR. Participants were classified by concomitant medial meniscal status: no medial meniscus involvement (n = 36), partial medial meniscectomy (n = 9), and medial meniscus repair (n = 11). Participants underwent biomechanical analyses during over-ground walking including surface electromyography; a validated musculoskeletal model estimated medial compartment tibiofemoral contact forces. Gait variables were analyzed using 3 × 2 ANOVAs with group (medial meniscus treatment) and limb (involved versus uninvolved) comparisons.ResultsThere was a main effect of group (p = .039) for peak knee flexion angle (PKFA). Participants after partial medial meniscectomy walked with clinically meaningfully smaller PKFAs in both the involved and uninvolved limbs compared to the no medial meniscus involvement group (group mean difference [95%CI]; involved: −4.9°[−8.7°, −1.0°], p = .015; uninvolved: −3.9°[−7.6°, −0.3°], p = .035) and medial meniscus repair group (involved: −5.2°[−9.9°, −0.6°], p = .029; uninvolved: −4.7°[−9.0°, −0.3°], p = .038). The partial medial meniscectomy group walked with higher involved versus uninvolved limb medial tibiofemoral contact forces (0.45 body weights, 95% CI: −0.01, 0.91 BW, p = 0.053) and truncated sagittal plane knee excursions, which were not present in the other two groups.SignificanceAberrant gait biomechanics may concentrate high forces in the antero-medial tibiofemoral cartilage among patients two years after ACLR plus partial medial meniscectomy, perhaps explaining the higher osteoarthritis rates and offering an opportunity for targeted interventions.Level of EvidenceLevel III.