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

We hypothesize that the articular surfaces of the carpals are shaped to optimally distribute contact loads. To test this hypothesis, we developed a congruence-based forward model and validated it with in vivo data. A single wrist was analyzed by taking a high-resolution MRI and three CT scans during a simulated hammering motion. In the kinematic model, two degrees of freedom (DOF) were imposed, while the remaining 40 DOF were computed to optimize load distribution. Maximum mean absolute errors (MAE) between CT measures and model predictions were 6.52° and 1.27 mm for rotations and translations, respectively. These preliminary results support the validity of the model and further confirm the functional relevance of the hammer motion.