The role of menisci in knee contact mechanics and secondary kinematics during human walking

Background: Meniscectomy is likely to result in an increase of joint loading on articular cartilage and initiates cartilage damages. However, the induced alterations in knee contact mechanics and secondary kinematics after the meniscal removal are still unclear during a walking gait. In this study, the role of menisci on the knee contact mechanics and secondary kinematics were investigated during a walking simulation. Methods: Two natural knee models with or without menisci were established using a musculoskeletal multibody dynamics framework. Walking simulation were performed to qualify the knee contact forces and secondary kinematics, and ligament forces in these models. Findings: After the meniscal removal, the redistributed contact forces on the medial tibial cartilage increased by twofold, while the contact area remained almost the same. The subsequent increase of contact pressure suggested potential cartilage damages. In terms of the kinematic alterations, the tibia moved more posteriorly and internally with respect to the femur. And, the displacement in the medial-lateral direction reversed. In addition, the sharp force increase in the anterior cruciate ligament explained the reason why meniscal and anterior cruciate ligament injuries always happened concurrently. And, the anterior lateral ligament may act as the stabilizer in the tibial posterior displacement and varus rotation. Interpretation: This study shows that menisci served as the joint load distribution, and also as the kinematics constraints in the posterior and medial-lateral direction, which is beneficial to the rehabilitation plan-making of meniscal injuries.