A combined magnetic resonance (MR) imaging method has been proposed to investigate individual’s knee functionality quantitatively under weight-bearing condition. High resolution MR data were acquired first to reconstruct the subject-specific anatomical model. A dynamic MR acquisition was obtained afterwards to record the motion of knee joint. A tri-rigid registration was applied to retrieve the knee joint motion, leading to a 12 degree-of-freedom (DoF) knee functional model. Using this model, the tibiofemoral contact mechanism was studied and analysed in both 2D and 3D. A mathematical definition of contact points of cartilage surfaces is given by modelling these surfaces as manifolds. It is believed that such subject-specific motion of contact points on cartilage surfaces of femur and two tibia plateaus can provide valuable insights for clinical applications such as knee replacement surgery.