Efficient Computation of Cartilage Contact Pressures within Dynamic Simulations of Movement.

The objective of this study was to assess the use of an advanced collision detection algorithm to simulate cartilage contact pressure patterns within dynamic musculoskeletal simulations of movement. We created a knee model that included articular cartilage contact for the tibiofemoral and patellofemoral joints. Knee mechanics were then predicted within the context of a dynamic gait simulation. At each time step of a simulation, ray-casting was used in conjunction with hierarchical oriented bounding boxes (OBB) to rapidly identify regions of overlap between articulating cartilage surfaces. Local cartilage contact pressure was then computed using an elastic foundation model. Collision detection implemented in parallel on a GPU provided up to a 10× speed increase when using high resolution mesh densities that had >10 triangles/mm2. However, pressure magnitudes converged at considerably lower mesh densities (2.6 triangles/mm2) where CPU and GPU implementations of collision detection exhibited equivalent performance. Simulated tibiofemoral contact locations were comparable to prior experimental measurements, while pressure magnitudes were similar to those predicted by finite element models. We conclude the use of ray-casting with hierarchical OBB for collision detection is a viable method for simulating joint contact mechanics in human movement.