“One of the most frequent sites of lameness is the hock joint,” said Hilary Clayton, BVMS, PhD, MRCVS, Mary Anne McPhail Dressage Chair in Equine Sports Medicine at Michigan State University (MSU), in her presentation “A New Look at the Hock Joint” at the 2003 Bluegrass Laminitis Symposium in Louisville, Ky. “Various shoeing modifications are used with the objective of modifying hock motion and/or force transmission across the joint; however, it is not possible to evaluate the effect of these treatments in the absence of reliable data describing normal and pathological function of the joint.”

Clayton presented the results of several MSU hock studies, beginning with a description of normal hock motion. The hock, she explained, is a very complex joint with several smaller joints between its many bones. The majority of its motion occurs at the tarsocrural joint (between the tibia and the talus in the upper joint of the hock. Aside from flexion and extension when viewed from the side, which is the primary motion, the hock also is capable of sliding and small amounts of lateral and rotational motion. “The distal tarsal joints are thought to undergo small amounts of movement during normal locomotion, and these movements may be important in the etiology of hock lameness, such as bone spavin,” she said