In vivo quantification of patellofemoral joint contact force using a mathematical model

Abnormal patellofemoral joint contact mechanics are speculated to play a role in cartilage degeneration. A two-dimensional joint contact model of the human patellofemoral joint was presented to quantify joint contact force and stress. Internal joint geometry was determined non-invasively using magnetic resonance imaging of the knee under physiologic loading conditions. Knee joint moment arms were determined from magnetic resonance images, measured from a functional joint centre calculated from individual knee kinematics. Hamstrings muscle forces were quantified for inclusion in the 2D patellofemoral joint model using a technique to estimate muscular force distribution non-invasively. Inclusion of these parameters in the patellofemoral joint contact model is expected to yield contact force and stress estimates that account for joint adaptations that may accompany knee injury or pathology. The methodology presented in this study was tested on healthy human knee joints to provide a basis for future comparison with injured subject groups.