Avulsion Fracture Causes and Treatments

An avulsion fracture is a bone injury that occurs when a piece of bone that attaches to a tendon or ligament is pulled off the rest of the bone. Avulsion fractures can occur anywhere in the body, but they are most common in the elbow, ankle, and hip.

Recovery from an avulsion fracture can take six weeks to six months, and surgery is not always needed. However, in children who have an avulsion fracture involving the growth plate, or the area of the bone that is actively growing, surgery may need to be done.

Causes 

Often an avulsion fracture occurs when there is a sudden forceful pull on a tendon while the bone is moving in the opposite direction. An example is an injury to the fifth metatarsal, the bone on the outside of the midfoot. The peroneal tendon attaches to the base of this bone.

Often when the foot is twisted, a forceful contraction of the peroneal tendon pulls the foot in one direction, while the twisting force is acting on the foot in the opposite direction. This causes the bone to crack where the tendon attaches to the bone. The good news is that these fractures almost always heal with simple rest and time. 

Diagnosis

An avulsion injury noted on an X-ray film can be confusing, because often these may be related to an old injury. Sometimes a small piece of bone pulled away from the body a long time ago, and only when an X-ray is obtained months or years later is the fragment of bone seen.

Treatment 

Most often, an avulsion fracture can be treated without surgery. Only when the pulled off fragment of bone is pulled more than several centimeters from its normal position does surgery need to be considered.

In addition, some avulsion fractures affect such small pieces of bone there's no need to repair them. For example, ankle sprains often cause small avulsion fragments. These injuries typically can be treated like an ankle sprain, as the small piece of bone really does not affect the treatment decisions or outcome of the patient.

There are some concerns about treatment when the avulsion fracture involves the growth plate in a child. Because growth plates are important for normal skeletal development, these injuries must be carefully treated. If there is a concern that a growth plate is not correctly positioned, surgery may be performed to align and stabilize the growth plate.

Surgery may not be needed if the avulsion fracture is well aligned, or if the patient is near enough to growth plate closure that this injury will not cause lasting growth problems.