Modeling the tendon-bone dynamic interaction while wrapping and unwrapping using bond graph.

The dynamic wrapping and unwrapping of tendons or ligaments around bones critically influence tendon stretch, bone-periosteum contact forces, and joint motion. Accurately modeling this interaction over irregular bone surfaces is complex. This study introduces a novel framework using 3D point cloud bone geometry enveloped by a soft periosteum layer, modeled via nonlinear stiffness and damping fields. Tendons/ligaments are represented as elastic strings with distributed point masses linked by nonlinear stiffness and damping. Multibond graph submodels capture the coupled dynamics between tendon, periosteum, and bone. Simulations in planar and 3D cases demonstrate the model's robustness, offering new insights into biomechanical motion and joint mechanics.