Bone and bone healing.

Bone is composed of cells and organic matrix (30%), and minerals (70%). A vascular network consisting of nutrient, metaphyseal, and periosteal vessels richly supplies adult bone. Fracture healing consists of three interrelated phases: inflammatory, repair, and remodeling, and culminates in the ability of bone to return to original tissue structure. Many growth factors and regulatory proteins have been implicated in bone repair. Of these, transforming growth factor-B appears to be the major regulator of bone metabolism. This regulates differentiation and proliferation of mesenchymal cells into chondroblasts, osteoblasts, and osteoclasts.