Improved rig for the analysis of knee behaviour under dynamic motion tasks

The evaluation of the knee joint behaviour is of great interest for medicine. A new rig to test knees in vitro in loaded and unloaded conditions is presented in this paper. Its loading system based on a cable-driven parallel manipulator allows the application of general loads typical of common daily activities. Its force-control permits the evaluation of the joint natural response to the loads in terms of movement, measured thanks to a stereophotogrammetric system. In addition, the principal muscles that control the knee flexion and extension can be simulated and their contributions to the joint equilibrium can be evaluated thanks to a dedicated control system. The rig is an evolution of a previously presented version, of which it preserves the low cost and simplicity, together with the versatility and accuracy.