The influence of loading conditions on equine hoof capsule deflections and stored energy assessed by finite element analysis

The biomechanical effects on the hoof capsule of the location of the centre of pressure of the ground reaction force may be important to understand the functioning of the hoof capsule. This study investigated the effect of changes in loading and contact friction on hoof deflections and elastic energy storage by varying the boundary conditions applied to finite element models. For all cases a load of 10 N kg−1, typical of the peak load in the trot gait, was used. In one scenario the coefficient of contact friction was varied from 0 (frictionless) to 1, at a constant non-zero joint moment, to simulate the effects of restriction of the hoof at the ground surface. In the other scenario a varying joint moment, with contact friction set at 0, was used to move the centre of pressure (COP) forward. Both increasing the ground surface friction and moving the COP forward caused the hoof capsule deflections and stored elastic energy to decrease. Peak strain energy in the capsule occurred when the frictional coefficient was 0 and when the COP was below the centre of rotation of the distal interphalangeal joint. Minimum strain energy occurred when the frictional coefficient was 1.0 and when the COP location was 30 mm forward of the joint centre. Hoof expansion and elastic energy storage are considerably influenced by ground surface friction and centre of pressure location. Therefore model validation studies should account for these parameters. Maximising the energy absorption may explain why heel first landing is preferred.