Modelling the Interaction Between Racehorse Limb and Race Surface

Musculoskeletal injuries are the leading cause of racehorse fatalities and attrition. Race surface mechanics affect racehorse limb biomechanics, and therefore can affect musculoskeletal injuries. Installation of experimental race surfaces to determine their effect on racehorse limb kinematics is not financially feasible. Furthermore, field data collection is time consuming, labor intensive, and requires the use of live animals. Computational modelling provides an economical option to survey a wide range of surface mechanics and resulting effects on racehorse limb motions. This research aimed to develop and evaluate an integrated racehorse limb and race surface computational model. The interaction of a virtual galloping racehorse impacting virtual race surfaces was modelled in SIMM using combined forward/inverse dynamics. In vivo kinematic data were averaged to determine proximal forelimb, trunk, and hindlimb kinematic model profiles throughout gallop stance, as well as distal forelimb initial conditions. All distal forelimb joints and hoof translations were free to respond to external forces applied by the race surface model during stance. Race surface model coefficients were determined from previously measured race surface mechanics and forward dynamic simulations of a track-testing device. Simulation results were compared to distal forelimb motions of actual galloping racehorses on mechanically measured race surfaces. Model predicted kinematic profiles (metacarpophalangeal angle and hoof translations) had qualitative shapes and peak magnitudes within ranges of experimental data. Simulated peak metacarpophalangeal angle and hoof translations were within 11 degrees and 4 cm respectively. Future model applications include estimation of the effects of variation in race surface parameters on racehorse limb biomechanics.