Knee joint mechanics - assessment and modeling

膝关节前交叉韧带（ACL）的完整性丧失或重建也会改变关节的稳定性和动力学，导致骨关节炎（OA）的风险和发病率增加。然而，关节结构中关节接触力学的直接无创体内量化一直受到限制。因此，正常健康的关节力学特征和导致病理状况的特征并没有很好地确定。此外，重建关节结构以重建损伤前关节力学的最佳标准和治疗方法也缺乏。研究的总体目标是了解关节力学、关节健康状况、关节损伤和修复机制之间的关系，以及与韧带损伤和修复相关的退行性变化的发展。本文将检验两个主要假设：（H1）关节错位、前交叉韧带缺陷和重建导致关节力学紊乱；（H2）前交叉韧带重建手术存在最佳几何形状和动态控制，可重建正常膝关节运动学和动力学。将对健康组、OA组、ACL缺失组和不同膝关节屈曲和负荷条件下重建的4组膝关节接触和组织特征进行成像和量化。使用新的图像配准技术，将开发组织特征的规范范围。将使用3D运动分析评估每个组的关节动态稳定性，并使用共同参考标记，肌电图和螺旋轴分析与关节结构的MR图像相关联。在动态运动范围内构建一个三维膝关节模型，包括。实验对象为特定的骨节、骨骼肌和被动组织。使用多体动力学和优化原理建立结构之间的运动学和动力学关系。验证后的三维数值模型将用于评估韧带重建变量对关节动力学和功能的影响。本研究将对膝关节结构损伤引起的关节力学变化产生更全面的理解，从而提高我们设计有效的关节健康诊断、治疗和设备的能力。

The loss of integrity or reconstruction of the anterior cruciate ligament (ACL) in the knee can also alter joint stability and dynamics and lead to higher risk and incidence of osteoarthritis (OA). However, direct non-invasive in-vivo quantification of joint contact mechanics within the joint structures has been limited. Consequently, characteristics of normal healthy joint mechanics, and those leading to pathological conditions are not well established. Further, the optimal criteria and treatments for reconstruction of joint structures to re-establish pre-injury joint mechanics are also lacking. The overall research goals are to understand relations amongst joint mechanics, joint health status, joint injury and repair mechanisms, and the development of degenerative changes associated with ligament injury and repair. Two main hypotheses will be tested: (H1) Joint malalignment, ACL deficiency and reconstruction result in perturbed joint mechanics, and (H2) an optimal geometry and dynamic control exists for an ACL reconstruction surgery that re-establishes normal knee joint kinematics and kinetics. Knee joint contact and tissue characteristics will be imaged and quantified for 4 in-vivo groups: healthy, OA, ACL deficient and ACL reconstructed under various knee flexion and loading conditions. Using novel image registration techniques, normative ranges for tissue characteristics will be developed. Joint dynamic stability will be assessed for each group using 3D motion analysis, linked to MR images of joint structure using common reference markers, EMG and helical axis analysis. A 3D knee joint model over a dynamic range of motion will be constructed including. subject specific bony segments, skeletal muscles, and passive tissues. Kinematic and kinetic relationships between structures will be established using principles of multibody dynamics and optimization. The validated 3D numerical model will be applied to evaluate the influence of ligament reconstruction variables on joint dynamics and function. This research will generate a more comprehensive understanding of changes in joint mechanics due to compromises of knee structure, thus enhancing our ability to design effective diagnoses, treatments and devices for joint health.