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

描述（由申请人提供）：该提案解决了当前的知识差距：为什么女性对ACL损伤的敏感性是男性的2至8倍。许多ACL损伤发生在跳跃时单脚着地或跑步和切割时。在01-03年，我们使用装有仪器的尸体结构来识别导致最大峰值ACL应变的脉冲复合3D载荷的方向：压缩+屈曲力矩+内部胫骨轴向扭矩。我们现在寻求资金，以使用这种尸体测试结构，完成非线性股四头肌拉伸刚度，以确定性别对峰值ACL相对应变在上述复合脉冲负载情况下的影响。每个膝关节最初将通过预张紧的股四头肌、内侧和外侧腘绳肌和腓肠肌肌腱等同物以15度的初始屈曲角定位，这些等同物允许膝关节在冲击载荷下屈曲。在AIM 1中，我们将在来自尺寸匹配尸体的22例男性和女性膝关节中检验以下假设：由于2*BW冲击力和上述复合冲击载荷，性别不会影响峰值ACL相对应变。初步数据表明，女性膝关节的ACL应变更大。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个尺寸匹配的膝关节来检验以下假设：与外侧优势肌肉力量相比，内侧优势股四头肌和腘绳肌膝关节肌肉力量显著增加ACL峰值相对应变，尤其是在女性中。试点数据表明情况确实如此。在AIM 3中，我们将使用重复测量设计来检验10个膝关节的假设，即在复合脉冲载荷下，将女性股四头肌肌肉等效物替换为更坚硬的男性对应物将显著降低女性膝关节的峰值ACL应变;在10个男性膝关节中，相应的效果将不会达到显著性。试点数据表明事实确实如此。这项研究的见解将有助于解决更好地了解性别在ACL损伤机制中的作用的迫切需要，以改善风险因素监测和预防计划。 公共卫生相关性：本研究的目的是更好地了解导致ACL损伤的机制，女性比男性更常见。考虑到女性ACL的横截面积较小，在AIM 1中，我们将使用完全内固定的尸体膝关节来检验假设，即在模拟跳跃着陆过程中，女性的峰值ACL应变大于相同尺寸的男性。在AIM 2中，我们将检验这一假设，即当腿部内侧和外侧穿过膝盖的肌肉力量不平衡时，女性的这种应变会升高。在AIM 3中，我们将测试这样的假设：增加女性股四头肌的拉伸刚度可显着降低ACL峰值应变。这项研究的见解应该有助于提高预防计划的有效性，以减少ACL损伤的风险，特别是在女性中。

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.