Primary and secondary restraints of human and ovine knees for simulated in vivo gait kinematics

Abstract

Knee soft tissue structures are frequently injured, leading to the development of osteoarthritis even with treatment. Understanding how these structures contribute to knee function during activities of daily living (ADLs) is crucial in creating more effective treatments. This study was designed to determine the role of different knee structures during a simulated ADL in both human knees and ovine stifle joints. A six degree-of-freedom robot was used to reproduce each species' in vivo gait while measuring three-dimensional joint forces and torques. Using a semi-randomized selective cutting method, we determined the primary and secondary structures contributing to the forces and torques along and about each anatomical axis. In both species, the bony interaction, ACL, and medial meniscus provided most of the force contributions during stance, whereas the ovine MCL, human bone, and ACLs of both species were the key contributors during swing. This study contributes to our overarching goal of establishing functional tissue engineering parameters for knee structures by further validating biomechanical similarities between the ovine model and the human to provide a platform for measuring biomechanics during an in vivo ADL. These parameters will be used to develop more effective treatments for knee injuries to reduce or eliminate the incidence of osteoarthritis.

Keywords: Activities of daily living; Anterior cruciate ligament; Knee kinetics; Meniscus; Ovine.

Figure 1

Human total force during gait. Sum of the average translational components of intact knee force and the corresponding drop in all structurally deficient knee forces during the gait cycle in the human knee joint. Human toe-off occurs at 64% of gait, though loading continues to be compressive. Bony interaction accounts for the majority of total load in stance and swing, followed by the medial meniscus.

Figure 2

Ovine total force during gait. Sum of the average translational components of intact knee force and the corresponding drop in all structurally deficient knee forces during the gait cycle in the ovine stifle joint. Ovine toe-off occurs at 68% of gait when loading is primarily distractive. Bony interaction accounts for the majority of total force in stance, followed by the medial meniscus. The MCL and ACL account for the majority in swing.