Fracture and repair of bones
Types of fracture
1. Open/ Compound fracture: The broken ends of bones extend beyond the skin.
2. Comminuted fracture: The bone is crushed into the pieces at the site of impact and the smaller fragments lie between two main fragments.
3. Greenstick fracture: One side of the bone is broken and the other side is bent.
4. Impacted fracture: One end of the bone is driven forcefully into the interior of the other part of the fractured bones.
5. Pott fracture: Fracture in the distal end of lateral leg bones (fibula).
6. Collesfracture: Fracture in the distal end of forearm leg bones (radius).
Steps of bone repair
1. Haematoma (mass of blood clot) formation Haematoma is formed usually within 6-8 hours of injury by the blood leak from the torn blood vessels of fracture line. Thereafter, blood circulation stops followed by the death of bone cells and migration of leukocyte to the site of injury. The neutrophils and macrophages then remove the dead cells and provoke the inflammatory responses, which lasts for several weeks.
2. Fibrocartilaginous callus formation: Collagen is produces by the fibroblasts, present in the Periosteum and fibrocaritlage is produced by the chondroblasts of the region which leads to the development of fibrocartilaginous callus that bridges the broken ends of the bone. At least 3 weeks is required to form fibrocartilaginous callus.
3. Bony callus formation: Spongy bone trabeculae is produced by osteoblasts following the formation of osteoblasts by osteogenic cells of healthy bone, near the fracture area. The trabeculae join the living bone with the dead portion of fragments followed by the formation of hard callus.
4. Bone remodelling: This is the final step of the repair where the dead portion of the fractured bone is removed by the Osteoclasts and the deposition of new collagen and minerals occur by the osteoblasts.
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