Bone structure and metabolism

The bones of the skeleton provide mechanical support for joints, tendons and ligaments, protect vital organs from damage and act as a reservoir for calcium and phosphate in the preservation of normal mineral homeostasis. Bone is a complex and dynamic tissue which undergoes renewal and repair throughout life as the result of bone remodelling. Most diseases of bone occur as the result of abnormalities in bone remodelling which compromise the architecture, structure and mechanical strength of bone, leading to clinical symptoms such as pain, deformity, fracture and abnormalities of calcium and phosphate homeostasis. Over recent years, tremendous advances have been made in defining the molecular mechanisms by which bone remodelling is regulated at a local level and how systemic hormones affect the expression of local regulatory factors to influence bone turnover. In this review bone development, anatomy and composition are discussed, together with a review of the molecular mechanisms by which bone remodelling is regulated.