Bone is composed of organic and inorganic elements. By weight, bone is approximately 20% water. The weight of dry bone is made up of inorganic calcium phosphate (65-70% of the weight) and an organic matrix of fibrous protein and collagen (30-35% of the weight).[10,19,21,22]
Osteoid is the unmineralized organic matrix secreted by osteoblasts. It is composed of 90% type I collagen and 10% ground substance, which consists of noncollagenous proteins, glycoproteins, proteoglycans, peptides, carbohydrates, and lipids.[20,22] The mineralization of osteoid by inorganic mineral salts provides bone with its strength and rigidity.
The inorganic content of bone consists primarily of calcium phosphate and calcium carbonate, with small quantities of magnesium, fluoride, and sodium. The mineral crystals form hydroxyapatite, which precipitates in an orderly arrangement around the collagen fibers of the osteoid. The initial calcification of osteoid typically occurs within a few days of secretion but is completed over the course of several months.
Neurosurg Focus. 2001;10(4) © 2001 American Association of Neurological Surgeons
Cite this: Principles of Bone Healing - Medscape - Apr 01, 2001.