A HYPOTHETICAL REGULATION MECHANISM OF ADAPTIVE BONE REMODELING - (TRANSPORT OF GROWTH-FACTORS BY MECHANICAL LOADS)

A hypothetical regulation mechanism of adaptive bone remodeling is proposed. In this hypothesis, the growth factors and bone cells are involved in the mechanim as follows: first osteoclasts activate the growth factors contained in the bone matrix and release them into bone fluid, then the growth factors are transported to the bone surface with fluid flow induced by the mechanical loads applied to the bone, and finally the growth factors transported regulate the activities of osteoblasts which are responsible for bone formation. It is shown that many curious features which have been reported for adaptive bone remodeling are explained by the proposed hypothesis. Furthermore, a simple analytical model is constructed based on the hypothesis, which can simulate some typical adaptation processes such as the adaptation to applied repetitive moments and the correction of abnormal curvature after misaligned fracture.