A study of constrained models for the kinematic analysis of the human knee joint

摘要

In a number of clinical applications such as ligament repair, joint replacement or prosthesis' design, the understanding of knee kinematics is of fundamental importance. Here, the determination of the joint rotation axes is crucial for the interpretation of joint kinematics. However, concurring definitions of knee joint axes based on anatomic landmarks are in use. Regarding any of these definitions, there is a large variability between observers and different sessions or trials. To reduce observer dependence, mathematical procedures based on movement analysis, the so-called functional methods, have been developed. Presently, a number of alternative concepts exist allowing for the determination of joint rotation axes (Ehrig et al. 2007). The finite helical axis (FHA) as an invariant description of joint displacements is a powerful tool; however, the FHA is not easy to interpret clinically (Woltring et al. 1987). Further approaches aim to bridge the gap between clinicians and engineers. The clinical protocol may be conserved whereas, subsequently, mathematical optimisation is used to reorient the clinically determined rotational axes, aiming at an optimal fit between the data and the underlying kinematic model (Baker et al. 1999; Marin et al. 2003). Therein, the intact human tibio-femoral joint (no ligament damage or osteoarthritis) is modelled as a compound hinge joint exhibiting only two rotational axes, flexion/extension (FE) and tibial rotation (TR).