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An ankle avulsion fracture occurs at the point where a tendon or ligament attaches to a bone. A force on the tendon or ligament, causes a piece of bone to be pulled away.
Symptoms of an ankle avulsion fracture are very similar to an ankle sprain and it is very difficult to tell the difference without an X-ray or MRI scan. There will be pain in the ankle immediately after the injury occurs with immediate swelling. Bruising may develop later and the athlete will most likely have difficulty moving or putting weight on the ankle.
Avulsion fractures can occur anywhere in the body, usually at joints. the ankle is one of the most common places for it to happen. When the ankle is sprained (twisted), a force is passed through the ligaments and tendons (usually on the outside of the ankle). One of two things can then happen. Either the ligament or tendon tears, resulting in a sprained ankle, or the ligament / tendon pulls so hard on its bony attachment, that it pulls a small piece of bone off.
It is impossible to know which of these has happened following an ankle injury, without an x-ray. This is why it is always important to get an x-ray following a moderate to severe ankle injury.
Although treatment is often the same whether there is an avulsion fracture or just a sprain, it may depend on the severity of the fracture and also its alignment. Children are also more likely to be offered alternative treatment for a fracture as otherwise this could affect their skeletal growth.
More severe avulsion fractures or fractures in children, may require casting for 6-8 weeks to allow the bone to heal. Following this, a period of rehabilitation will be required to ensure that full strength and mobility are regained.