Broken bones

Fractures

If you haven't broken a bone yourself, you probably know someone who has. There are many different types of fracture, the most common of which is a simple fracture, when a bone breaks cleanly. If you put out your arms when you fall, you could end up with an impacted fracture, where the ends of two bones are forced into one another. A sharp sudden twist of a bone in a game of football could result in a jagged spiral fracture. Road accidents often cause comminuted fractures, where a bone breaks into fragments, or compression fractures, where a bone is crushed.

Realignment

In order to stop broken bones from healing in the wrong shape, it is important that they are realigned. The bones can be coaxed back into position by a doctor's hands, or the bone ends can be secured together with pins and wires. If a bone is severely fractured in several places, an incision is made in the skin to expose the bone, and a combination of plates, wires, screws, rods and nails are inserted to hold the pieces of bone in place. The broken bones are then immobilised, often with a plaster cast, so they can start to heal.

Repair

Simple fractures usually take about 6-8 weeks to heal, although larger or elderly bones take longer. There are four main steps to bone repair:

1. The blood vessels ruptured in a broken bone cause a blood filled swelling called a haematoma at the site of the fracture


2. A cartilage callus forms in place of the haematoma. It acts to splint the broken bone


3. A bony callus forms, replacing the cartilage with a callus made of spongy bone


4. The bony callus remodels in response to stress placed on it, forming a strong, permanent patch at the fracture site

Source: http://www.bbc.co.uk/science/humanbody/body/articles/skeleton/broken_bones.shtml