Prediction of individual carpal kinematics during hammer motion: an in-vivo validation

The relationship between form and function of the carpal joint during functionally relevant tasks remains unclear. We hypothesize that the articulations are shaped by an adaptation process aiming at optimally distribute contact loads [1]. The goal of this study was to test this hypothesis by simulating a hammering motion using assumptions of optimal congruence. The hammer motion was chosen because it represents a functionally relevant task, optimized in terms of radiocarpal stability [2]. To test this hypothesis, we developed a congruence-based forward model and validated it with in vivo data. In the model, two degrees of freedom (DOF) were imposed, while the remaining 40 DOF were computed to optimize load distribution by maximizing a measure of the joint congruence [3]: the more congruent the articular surfaces, the smaller the peak contact pressure. This approach was previously validated for the ankle and the knee [4,5] and is here tested on the wrist.