A simple rig for precise measurements of the knee and ankle joint motion under static loading conditions

In this paper a rig for the analysis of the motion of the knee and ankle joints under static loading conditions is presented and described. The rig is simple, versatile and precise: experimental tests can be performed both on the knee and ankle joints, by a wide range of anatomical specimen sizes; the loads applied to the joints during tests can be measured and controlled with a high precision; specimen position and orientation can be precisely set. Thus, this structure makes it possible to measure precise and repeatable experimental data on the joint motion under static loading conditions, by means of a stereophotogrammetric device. Such experimental data are generally not available in the literature, where all details on the loading conditions are generally not reported, but are necessary in many applications, such as joint modelling and prosthesis and orthosis design.