Knee shape is associated with kinematic changes during deep flexion

Knee shape is intimately linked to the kinematics of the knee joint. Deep flexion is important for both cultural and recreational activities. However, the relationship between knee shape and kinematics in deep flexion are not well understood. The aim of this study was to examine the association between shape and kinematics during kneeling. Statistical shape models were generated for the femur and tibia by running a PCA on aligned bony meshes generated from CTs. Six-degree-of-freedom kinematics were calculated by registering 3D-static CT onto the 2D-dynamic fluoroscopic images. Variations in geometry of the knee were associated with kinematics of the knee joint during kneeling. Specifically, increased femoral mediolateral width, posterior-condylar height, and axial-condylar orientation, were associated with a more posterior-medial femoral position. A flatter tibial plateau and increased tibial-spine height were associated with a more internally rotated tibia at 120°.