Development of a kinematic 3D carpal model to analyze in vivo soft-tissue interaction across multiple static postures.

We developed a subject-specific kinematic model to analyze in vivo soft-tissue interaction in the carpus in static, unloaded postures. The bone geometry was extracted from a reference computed tomography volume image. The soft-tissue geometry, including cartilage and ligament tissues, was computationally modeled based on kinematic constraints; the constraints were extracted from multiple computed tomography scans corresponding to different carpal postures. The data collected in vivo was next coupled with numerical simulation in order to analyze the role of soft-tissues in different postures. The resulting model extends the state of biomechanical modeling by incorporating soft-tissue constraints across the carpus range of motion, while successfully using only physiological constraints. The model results suggest that soft-tissue wrapping constraints have substantial impact on carpus stability.