Effect of 3-D Compound Impulsive Loading on Relative ACL Strain

描述（由申请人提供）：本提案解决了当前的知识差距：为什么女性比男性更容易发生前交叉韧带损伤2至8倍。许多前交叉韧带损伤发生在单脚起跳或奔跑和切割时。在01-03年，我们使用仪器化的尸体结构来确定导致最大峰值ACL应变的脉冲复合三维载荷的方向：压缩+弯曲力矩+胫骨内轴向扭矩。我们现在正在寻求资金来使用这种具有非线性股四头肌拉伸刚度的尸体测试结构，以确定在上述复合脉冲加载情况下性别对前交叉韧带峰值相对应变的影响。每个膝盖最初将通过拉伸股四头肌、内侧和外侧腘绳肌以及腓肠肌肌腱，使膝盖在脉冲负荷下弯曲，初始屈曲角度为15度。在AIM 1中，我们将在22名来自尺寸匹配的尸体的男性和女性膝盖上测试假设，性别不影响由2*BW脉冲力和上述复合脉冲载荷引起的前交叉韧带相对应变峰值。试验数据显示，女性膝盖的前交叉韧带损伤更大。在AIM 2中，为了进一步描述损伤机制，我们将使用重复测量设计和22个尺寸匹配的膝盖来验证假设，即与外侧优势肌肉力量相比，内侧优势股四头肌和腿筋膝盖肌肉力量显著增加前交叉韧带相对应变峰值，特别是在女性中。试点数据表明情况就是如此。在AIM 3中，我们将使用重复测量设计来测试10个膝盖的假设，即在复合脉冲载荷下，将女性股四头肌等量肌肉与更硬的男性股四头肌等量肌肉交换将显著降低女性膝关节的前交叉韧带峰值应变；10 .男性膝盖相应的效果不会达到显著性。试点数据表明，情况确实如此。这项研究的见解将有助于解决迫切需要更好地了解性别在前交叉韧带损伤机制中的作用，以改善风险因素监测和预防方案。

DESCRIPTION (provided by applicant): This proposal addresses a current knowledge gap: why women are 2 to 8-fold more susceptible to ACL injury than men. Many ACL injuries occur when landing on one foot from a jump or when running and cutting. In Years 01-03 we used an instrumented cadaver construct to identify the direction of the impulsive compound 3-D loading that causes the largest peak ACL strain: compression + flexion moment + internal tibial axial torque. We now seek funds to use this cadaver testing construct, complete with non-linear quadriceps tensile stiffness, to determine the effect of gender on peak ACL relative strain under the above compound impulsive loading scenario. Each knee will initially be positioned at an initial flexion angle of 15 degrees via pretensioned quadriceps, medial and lateral hamstring and gastrocnemius muscle-tendon equivalents that allow the knee to flex under the impulsive load. In AIM 1 we will test the hypothesis in 22 male and female knees from size-matched cadavers that gender does not affect the peak ACL relative strain due to a 2*BW impulsive force and the above compound impulsive loading. Pilot data suggest ACL strain is larger in female knees. In AIM 2, to further delineate the injury mechanism, we will use a repeated measures design and 22 size-matched knees to test the hypothesis that medially-dominant quadriceps and hamstring knee muscle forces significantly increase peak ACL relative strain compared to laterally-dominant muscle forces, especially in females. Pilot data suggest this to be the case. In AIM 3 we will use a repeated measures design to test the hypothesis in 10 knees that swapping out the female quadriceps muscle-equivalent with a stiffer male counterpart will significantly reduce the peak ACL strain in the female knee under the compound impulsive loading; in 10 male knees the corresponding effect will not achieve significance. Pilot data suggest this is indeed the case. Insights from this research will help address the urgent need to better understand the role of gender in the mechanism of ACL injury to improve both risk factor surveillance and prevention programs. PUBLIC HEALTH RELEVANCE: The goal of this research is to better understand the mechanisms causing ACL injuries to be more common in women than men. Given the smaller cross-sectional area of the female ACL, in AIM 1 we will use fully instrumented cadaver knees to test the hypothesis that the peak ACL strain during a simulated jump landing is larger in females than males of the same size. In AIM 2 we will test the hypothesis that this strain is elevated in the female when the muscle forces crossing the knee on the inside and outside of the leg are not balanced. In AIM 3 we will test the hypothesis that increasing the tensile stiffness of the female quadriceps muscle significantly reduces peak ACL strain. Insights from this research should be useful for improving the efficacy of prevention programs designed to reduce the risk of ACL injury, particularly in females.