A fracture is simply a broken bone. Why do bones break? They are very rigid. They have to be, in order to form a strong skeleton to support the body and protect the softer tissues in the body. But this rigidity means that they can only bend a little bit when an outside force hits them. If that force is too great for the bone to absorb the impact, the bone will break, or fracture.
There are many different types of fractures. A weak force may only crack a bone rather than causing a clean break. This is known as an incomplete fracture. One common type of incomplete fracture is a greenstick fracture, in which the bone is bent. It occurs most often in children, whose bones are not as hard as adults'.
A very strong force may shatter a bone. There are also open and closed fractures. In a closed fracture, the broken ends of the bone do not protrude through the skin. The bones do protrude through the skin in an open fracture, which is sometimes called a compound fracture.
If the muscle has pulled a portion of the bone away from the site where it is normally attached, this is called an avulsion fracture. In an impacted fracture, the broken ends of a bone drive into each other.
In a stress fracture -- common among athletes -- tiny fractures are caused by repeated jarring and overuse of a bone. Bones that are weakened or damaged by disease can sometimes cause fractures called pathological fracture. Spiral or oblique fractures are usually caused by sudden violent twisting movements, such as twisting the leg or ankle during a fall. Compression fractures occur because of extreme pressure on the bone.
The only way to diagnose a fracture is through medical examination or X-rays. Contrary to popular belief, it is often possible to use a fractured arm or leg, although it may be painful or difficult.

