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May 2007 • VOLUME 21 • © HORSES For LIFE™ Magazine
Bone Remodeling of the Equine Distal Limb Mark D. Fischer M.D. Orthopedic Surgeon University Minnesota, USA. Sheri L. Fischer R.N., B.S.N. Fischer Equine Lameness Foundation www.Healthehoof.com INTRODUCTION The coffin bone (third phalanx) provides structural support and an internal mold for the hoof. It also transmits weight up the axial skeleton of the legs. Conditions which result in the loss of bone tissue in the coffin bone are devastating, because loss of substance from this bone typically cannot be recovered, and the change in the architecture of the coffin bone results in pathologic adaptations of the hoof and its supporting structures. Alterations in posture and gait to accommodate, lead to further maladaptations. Much of the rationale for trimming is to preserve the position and integrity of the coffin bone. This paper will describe the cellular mechanisms of bone loss as well as bone formation. The concept of bone remodeling and the circumstances in which it occurs will be discussed. The paper will also describe the influence of mechanical forces on bone remodeling (Wolfe's law). It is tempting to think of bone as inert structural supporting tissue, but unlike girders in a building, bone is biological tissue which has living cells, a blood supply (pipeline of nutrients), and it reacts to both chemical and mechanical influences by changing its own internal and external structure.
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