Using Spherical Contact Pairs to Model the Contact Areas in the Joints of the Wrist

This study aimed to analyze the possibility of using spherical contact pairs to model the articular surfaces of the joints of the wrist. To do so, a three-dimensional surface model of the bones in the wrist was created based on medical scans from computer tomography. Twenty-two pairs of surfaces, which represented the contact areas, were selected and cut out of the model. After that, these pairs were imported into custom software in Python, which allowed for numerical sphere fitting using optimization. The obtained results were then analyzed in terms of the validity of the obtained contact pairs, whether they formed actual ball-and-socket joints and based on fit quality. To verify the results obtained from the first model, a second set of meshes was obtained. The obtained results showed that for most of the joints in the wrist, the spherical approximation might be a viable choice. In some of the cases, the returned radii of the spheres were unusually large, which could mean that different contact pairs, such as the sphere-plane type might be more accurate.