A three-dimensional multivariate model of passive human joint torques and articular boundaries

OBJECTIVE: The development of a novel three-dimensional mathematical model of passive human joint torques that is of practical use, takes into account the complex non-linear interactions that exist between the moments generated by the various passive structures spanning the joint in question, and is applicable to all types of articular joints. DESIGN: Mathematical model validated by practical implementation. BACKGROUND: Previous models of passive human joint torques were predominantly one-dimensional and did not take into account the interactions of the various structural components. METHODS: Mathematical modelling is used in conjunction with repeated passive torque experiments on the right elbow joint of a healthy 29-year-old male. On the basis of the experimentally observed torque-angle data, the full set of articular model parameters characterizing the two-dimensional passive elastic torque function of the subject's right elbow joint could be determined. RESULTS: In addition to the passive elastic torque functions, the two-dimensional contour of the elbow joint's articular boundaries was also obtained. CONCLUSIONS: The present model is especially useful for assessing certain pathological conditions in any body joint investigated, and in addition is best suited for the inclusion in large-scale dynamic simulation models of the human neuromusculoskeletal system.