Learn about Repair of Bone in this educational video from dizzo95.
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Male Speaker: The fracture of a bone is usually caused by direct violence or by a strong twisting strain. When a bone fracture is the two fragments separate and in so doing tear the arties in the have a shunt systems across the fracture line. This damage results in the leakage of blood into the fracture were it is trapped soon clots. After a short time the haversian arteries go in to spasm causing the death of active bone cells not only at the fracture side but also fro some distance along the shaft. About two days after the break the blood clot is invaded by capillaries and fibroblast. The fibroblasts differentiate into bone forming cells or osteoblast and cells that form periosteal tissue on the outside of the bone. New tissue called callus surrounds the fracture and replaces the dead bone. The dead bone is absorbed and replaced by new bone born by osteoblast and the callus which is remodeled by cells called osteoblast to its original shape. This remodeling process is so effective that after a few months it is difficult to detect the fracture side.