Biomechanical Modeling of Finger Joints Based on Dimeric Kinematics

Abstract In the literature, the proximal and distal interphalangeal joints (PIP and DIP) are usually described as singleaxis hinge joints, whereas the metacarpophalangeal (MCP) joint is typically described as a two-axis joint. Biomechanical research studies revealed that due to the anatomical incongruence between the articular head (condyle) and the concave base of the adjacent phalanx, there exist additional rotational and translational movements. These findings indicate that the human finger joint is not a single-axis joint but rather a dimeric joint system. This study focuses on the accurate kinematic model to represent the configuration space and the biomechanical forces of the dimeric system. The configuration space of the single-axis hinge joint model is a subspace of the dimeric system’s configuration space. Vice versa, the dimeric system’s configuration space is a manifold over the single-axis system’s configuration space, enabling an uncountable set of configurations for each configuration of the subspace. This study enhances the understanding of the human finger kinematics as a basis for developing more realistic biomechanical models.