McPherson April L, Bates Nathanial A, Schilaty Nathan D, Nagelli Christopher V, Krych Aaron J, Hewett Timothy E
Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, Minnesota, USA.
Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
Orthop J Sports Med. 2018 Apr 9;6(4):2325967118765978. doi: 10.1177/2325967118765978. eCollection 2018 Apr.
Limb asymmetries, as determined through in vivo biomechanical measures, are known risk factors for anterior cruciate ligament (ACL) injury. Previous cadaveric studies have shown a lack of significant differences in ligament strain between contralateral lower extremities when identical kinematics were simulated on specimens. Recent methodological developments have applied in vivo knee kinetics to exert landing forces on cadaveric lower extremities to mimic ACL injury events, but it is unknown whether contralateral limbs fail in a consistent manner during impact simulator testing.
It was hypothesized that contralateral lower extremities would not exhibit side-to-side differences in ligament strains. Furthermore, it was hypothesized that failure loads and failure locations would be independent of limb dominance.
Controlled laboratory study.
Fourteen pairs of cadaveric lower extremities were obtained from an anatomic donations program (8 female, 6 male; mean ± SD: age, 41.7 ± 8.1 years; mass, 86.8 ± 27.0 kg; body mass index, 29.4 ± 9.0 kg/m). A mechanical impact simulator was used to re-create the impulse ground-reaction force generated during an in vivo landing task. Ligament strains were recorded by differential variable force transducers implanted on the ACL and medial collateral ligament (MCL).
No significant differences were observed in peak ACL or peak MCL strain for 5 loading conditions. Fisher exact tests of independence revealed that limb dominance was independent of both load at failure and failure location.
There were no significant differences in ACL and MCL strain values between limb sides during in vitro impact simulation testing. This finding indicates that limb dominance does not influence the failure threshold of the ACL, since there was no significant difference in failure strains. The functional mechanics of the ACL are comparable between contralateral pairs from the same healthy specimen.
Injury mechanisms and intra-articular mechanics cannot be ethically studied in an in vivo setting. The current study provides additional insight into limb asymmetry that is observed among athletes in clinical sports medicine settings.
通过体内生物力学测量确定的肢体不对称是前交叉韧带（ACL）损伤的已知风险因素。先前的尸体研究表明，在标本上模拟相同运动学情况时，对侧下肢之间的韧带应变没有显著差异。最近的方法学进展已将体内膝关节动力学应用于对尸体下肢施加着陆力，以模拟ACL损伤事件，但尚不清楚在冲击模拟器测试期间对侧肢体是否以一致的方式失效。
假设对侧下肢在韧带应变方面不会表现出左右差异。此外，假设失效负荷和失效位置与肢体优势无关。
对照实验室研究。
从解剖捐赠项目中获取14对对侧尸体下肢（8名女性，6名男性；平均±标准差：年龄，41.7±8.1岁；体重，86.8±27.0千克；体重指数,29.4±9.0千克/平方米）。使用机械冲击模拟器重新创建体内着陆任务期间产生的脉冲地面反作用力。通过植入ACL和内侧副韧带（MCL）上的差动可变力传感器记录韧带应变。
在5种加载条件下，ACL峰值应变或MCL峰值应变均未观察到显著差异。费舍尔独立性精确检验表明，肢体优势与失效时的负荷和失效位置均无关。
在体外冲击模拟测试期间，肢体两侧的ACL和MCL应变值没有显著差异。这一发现表明，肢体优势不会影响ACL的失效阈值，因为失效应变没有显著差异。来自同一健康标本的对侧肢体之间，ACL的功能力学具有可比性。
损伤机制和关节内力学在体内环境中无法进行符合伦理的研究。本研究为临床运动医学环境中运动员之间观察到的肢体不对称提供了更多见解。
