The Importance Of Including Knee Joint Laxity In Dynamic Musculoskeletal Simulations Of Movement

Download or read book The Importance of Including Knee Joint Laxity in Dynamic Musculoskeletal Simulations of Movement written by and published by . This book was released on 2012 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Musculoskeletal simulations of movement are often used to estimate soft tissue and joint contact loads. However, traditional modeling approaches do not incorporate knee laxity, which could affect both kinematic and kinetic estimates. The first objective of this study was to empirically assess how in vivo knee kinematics vary with quadriceps loading. Dynamic magnetic resonance imaging was used to track knee kinematics during a cyclic task in which quadriceps activity was induced with knee extension or flexion. The results show that quadriceps loading in a flexed knee induces a significant inferior shift of the finite helical axis of the tibiofemoral joint, which diminishes the patellar tendon moment arm about the knee. The second objective was to investigate whether a muscle-actuated computational knee model that includes ligament compliance and tibiofemoral contact could emulate in vivo kinematic patterns. A co-simulation framework was implemented in which neuromusculokeletal dynamics and knee mechanics were simultaneously solved. The co-simulation model predicted similar load-dependent variations in knee kinematics as seen in vivo, with predictions being dependent on both ligament compliance and the loading state. The final objective was to use the co-simulation framework to investigate the influence of knee laxity on tibiofemoral kinematics and kinetics during walking. Muscle activation patterns were computed that drove a lower extremity musculoskeletal model to track normal hip, knee, and ankle flexion patterns during gait. During the load acceptance phase of gait, the models with laxity predicted increased anterior tibia translation and internal tibia rotation due to quadriceps loading. These variations in tibiofemoral kinematics resulted in a more inferior finite helical axis, a diminished patellar tendon moment arm, and increased quadriceps loading, relative to what would be computed using a traditional kinematic knee model. Simulating gait with an ACL-deficient knee shifted tibia plateau cartilage contact posteriorly and laterally, which is a biomechanical affect that could contribute to early onset knee osteoarthritis. It is concluded that a co-simulation framework that incorporates joint laxity is important when using models to predict the effect of injury, surgical, and rehabilitation strategies on knee mechanics during human movement.