Abstract:
The biomechanics of the equine hoof are not well understood. Therefore biomechanical models of the hoof were developed, using finite element analysis and finite deformation elasticity, to provide a means of analysing the mechanisms underlying hoof function and dysfunction. One goal of the research was to investigate the biomechanical effects of different hoof shapes. A parametric geometry model that could be configured to represent commonly observed variations in hoof shape was developed for this purpose. Tissue behaviour models, accounting for aspects of the nonlinearity, inhomogeneity due to a moisture gradient and anisotropy of the tissues, were developed and configured using data from the literature. A method for applying joint moment loads was incorporated into the model to allow the direct use of published hoof load data. These aspects of the model were improvements over previously published hoof models. Both hoof capsule deflections and stored elastic energy were predicted to be increased by increased moisture content and by caudal movement of the centre of pressure of the ground reaction force. These results confirm that hoof deflections may play an important role in attenuating potentially damaging load impulse energy and support the geometry hypothesis to explain the mechanism by which the hoof expands under load. Further analyses provided insights into aspects of hoof mechanics that challenge conventional beliefs. The model predicts that load in the dorsal lamellar tissue is increased, rather than decreased, when hoof angle is increased. Simulations of different ground surface shapes indicate that hoof deformability and not ground deformability, may be responsible for the concave quarter relief observed in naturally worn hooves. A hypothesis is proposed for the mechanism by which heel contraction occurs and implicates heel unloading due to bending of the caudal hoof capsule and contraction under load bearing of the caudal coronet as probable causes. Biomechanical analyses of this kind enable improved understanding of hoof function, and a rational, objective basis for comparing the efficacy of different therapeutic strategies designed to address hoof dysfunction.