A FINITE-ELEMENT MODEL OF THE PROXIMAL SESAMOID BONES OF THE HORSE UNDER DIFFERENT LOADING CONDITIONS

Fracture of the proximal sesamoid bones is a common injury of racing h orses, usually resulting from over-dorsiflexion of the metacarpophalan geal joint. The purpose of this study was to develop a computer-aided method utilizing stereo-radiography, computed tomography, and finite e lement method to determine three-dimensional stress distribution in th e proximal sesamoid bones during metacarpophalangeal joint dorsiflexio n. The stress pattern was characterized by a compressive component on the articular part of the bone and a tensile component on the non-arti cular part of the bone. Maximum principal stresses were 2.5, 9.1 and 1 5.5 MPa and minimum principal stresses were -1.9, -9.2 and -14.9 MPa f or metacarpophalangeal joint angles of 140-degrees, 125-degrees- and 1 10-degrees, respectively. The distal portion of the articular part of the bone experienced the largest compressive stress. In this study cha nges in the orientation and magnitude of the ligament force vectors di d not significantly change stress patterns of the proximal sesamoid bo ne.