ABSTRACT
Bone is a dense, semi rigid, porous, calcified connective tissue forming the major portion of the skeleton of most vertebrates. It consists of a dense organic matrix and an inorganic mineral component. Bone remodelling is a complex process by which old bone is continuously replaced by new tissue, which requires interaction between different cell phenotypes and is regulated by a variety of biochemical and mechanical factors. In a homeostatic equilibrium, the process of resorption and formation are balanced so that old bone is continuously replaced by new tissue and it adapts to mechanical load and strain. Several local and systematic factors which cause disturbances in bone resorption and deposition leads to abnormal or defective development of bone commonly termed as osteodystrophy - A defective ossification of bone usually is associated with disturbed calcium and phosphorus metabolism. The better understanding of molecular cellular biology and pathogenic mechanism aids to define the abnormalities in osteoblastic and osteoclastic lineages and to develop new therapeutic approaches.
