# Bone Fractures and Repair A **fracture** is a medical term for a broken bone, occurring when the physical force exerted on the bone is stronger than the bone's structural integrity. ## Common Types of Fractures - **Simple (Closed) Fracture:** The bone is broken, but the overlying skin remains intact. - **Compound (Open) Fracture:** The broken bone ends penetrate the skin, creating an open wound. This carries a higher risk of infection. - **Complicated Fracture:** A fracture that causes damage to adjacent organs or tissues. ## Bone Repair Bone is a living tissue capable of self-repair. The healing of a simple fracture occurs in four main stages: ### 1. Haematoma (Clot) Formation - Immediately after the fracture, blood vessels within the bone and surrounding tissues are torn, leading to haemorrhage (bleeding). - A **haematoma** (a mass of clotted blood) forms at the fracture site. - Bone cells deprived of their nutrient supply die. - The area becomes swollen, painful, and inflamed. ### 2. Fibrocartilaginous (Soft) Callus Formation - Occurs within a few days. - New capillaries grow into the haematoma. - Phagocytic cells (like macrophages) invade the area to clean up cellular debris. - The ruptured periosteum stimulates **osteoblasts** (bone-building cells) and cartilage-forming cells. - These cells secrete a porous mass of bone and cartilage called a **callus** (or soft callus), which replaces the blood clot and splints the broken ends together. - This stage takes approximately three to four weeks. ### 3. Bony Callus Formation (Callus Ossification) - Beginning about a week after soft callus formation, it is gradually converted into a **bony callus** of spongy bone. - **Osteoclasts** (bone-resorbing cells) break down the cartilage. - **Osteoblasts** replace the cartilage with bone. - A firm union of the bone ends is typically formed after about two months. ### 4. Bone Remodelling - This is the final phase, where the bony callus is remodelled. - Compact bone is formed across the fracture line to connect both sides. - **Osteoclasts** remove the excess bone material produced during healing. - The final structure of the repaired area resembles the original unbroken bone, as it adapts and responds to mechanical stressors. ## Science, Technology and Society Connections - **Improper Posture and Bone/Joint Health:** Maintaining improper posture increases stress on joints and their supporting structures. This can lead to injury, chronic pain, and premature degeneration of bones and joints.