Meeting Abstract

11.5  Monday, Jan. 4  Cushioning the blow: Foot-substrate interactions in elephants MILLER, C.E.*; REN, L.; HUTCHINSON, J.R.; Royal Veterinary College, University of London; Kings College, University of London; Royal Veterinary College, University of London cmiller@rvc.ac.uk

Although the external features of the elephant’s foot appear relatively simple, the underlying anatomy is far more complex, comprising a full complement of five ‘true’ digits, and a cartilaginous rod, known as the ‘predigit’. These bones are embedded in a large, fatty, fibrous foot pad, which is in turn encased in a thick, highly keratinised slipper of skin. In walking the foot rolls over from heel to toe, with a lateral bias in pressure distribution, and a medial shift during toe-off, much like that seen in apes and humans. The fatty heel pad deforms significantly under the applied forces. But what happens below the surface? How do the digits and predigits react to load? Here we use computed tomography (CT) scanning to track the movements of the bones and cartilaginous structures of the elephant’s foot under controlled load application. We assess these internal movements in the context of external deformations recorded using motion analysis techniques in vivo, and in cadaveric studies under controlled loading conditions. We focus on the movements of the predigits, whose function is postulated as support to prevent collapse of the fatpad under load. In addition we compare differences in fore and hindlimb loading conditions with differences in the underlying anatomy. By gaining a better understanding of the biomechanics of the elephant’s foot, the area of interaction between the largest living land animal and the ground, we can gain insight into other, less extreme animal-substrate interactions, and gain a better understanding of the energy storage and vibration damping mechanisms involved.