A Workspace Analysis for a Planar Model of a Tibiofemoral Joint - A Preliminary Study

Abstract

The aim of this study was to compute and analyze the workspace of a tibiofemoral joint. To facilitate this research, an established, planar multibody model the joint was used. The model was composed of two rigid bodies corresponding to the tibia/fibula complex and the femur. These bodies were connected by a system of four nonlinear cables representing the ligaments and two Hertzian contact pairs, which modeled the cartilage of the knee. The workspace was computed by iteratively modifying the location of the tibia/fibula segment, specified by two linear coordinates and one angular coordinate. At each location, custom software prepared in Python iterated over the six elements of the joint and computed the loads that they generated. These loads were then compared to the maximal safe loads taken from published experimental studies. The obtained workspace of the tibiofemoral joint was moon-shaped with varying thickness. The largest workspace area was observed for a partially bent knee at 40.00°. Furthermore, significant reductions in the workspace were noted for hyperextension and deep flexion.