Bates Nathaniel A, Schilaty Nathan D, Krych Aaron J, Hewett Timothy E
Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, Minnesota, USA.
Orthop J Sports Med. 2019 Nov 27;7(11):2325967119884906. doi: 10.1177/2325967119884906. eCollection 2019 Nov.
The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC.
To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC.
Descriptive laboratory study.
A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors.
Strain responses during simulated landing tasks for the ACL ( ≥ .545) and MCL ( ≥ .489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL ( < .001) and MCL ( < .001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC.
Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture.
Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.
现有文献已充分探讨了着陆任务中初始接触（IC）时及之后膝关节韧带的动力学和应变情况。然而，对于IC之前飞行过程中膝关节韧带的生物力学情况却知之甚少。
量化并比较IC之前相对于IC之后前交叉韧带（ACL）和内侧副韧带（MCL）应变的变化。
描述性实验室研究。
在机械冲击模拟器中对40个尸体标本进行模拟着陆实验后进行分析。施加不同大小的外部关节负荷，以模拟来自体内队列的相对损伤风险负荷水平，并结合冲击力来代表初始地面接触。植入的应变片持续记录韧带应变。Kruskal-Wallis检验评估风险水平以及IC前后因素的显著性，而Wilcoxon配对检验评估两个因素内部的差异。
在每次模拟着陆任务中，无论每次试验模拟的相对损伤风险水平如何，IC之后ACL（≥0.545）和MCL（≥0.489）的应变反应都是一致的。在IC之前，施加于标本的损伤风险动力学水平可区分ACL（<0.001）和MCL（<0.001）的应变反应，因为更高的风险概况会使韧带应变产生更大变化。ACL的平均基线应变为4.0%，MCL为1.0%。ACL应变的平均变化在IC之前为0.1%至3.9%，在IC之后为2.9%至5.7%，而MCL在IC之前为0.0%至3.0%，在IC之后为0.9%至1.3%。
在每条韧带内，IC之后的应变反应在模拟风险概况之间缺乏统计学差异，而IC之前反应取决于模拟的风险概况。单独来看，IC前后的应变变化都不足以导致ACL断裂，但在整个着陆任务过程中综合起来，它们可能导致破裂。
预防和康复技术应旨在限制着陆前飞行中增加风险生物力学的出现，因为IC时的冲击力传递是不可避免的。
