Peroneal Tendon Injury

The peroneal tendons are two tendons that lie immediately behind the outside bone of the ankle (the fibula). These two tendons are responsible for moving the foot outwards in a direction called eversion. They are important tendons because they balance the ankle and the back of the foot and prevent the foot from turning inwards repetitively. They are slightly weaker than the muscles and tendons on the inside of the ankle and are prone to injury as the ankle turns, rolls or becomes sprained.

Tears of these tendons do occur. One or both of the tendons can be torn. This leads to swelling, pain and a sense of instability behind the outside of the ankle. Occasionally the tendons can be injured in either a fall or an athletic injury. They pop out of the supporting ligaments that hold them in place and dislocate. Once this occurs, recurrent dislocation and tearing of the tendons is inevitable.

If the tendons dislocate acutely in an injury, they need to be repaired to prevent future tearing of the tendons.

The peroneal tendons were dislocated in an acute twisting injury. Left: Note the ridge of tendons lying in front of the ankle. Right: The thumb is attempting to push the tendons back. Once dislocated, the tendons can only be replaced through surgery.

The diagnosis of peroneal tendon injury is made through careful examination and palpation by the orthopedic surgeon. An MRI may be required to more clearly document the extent of the tear. Once a tear is diagnosed, surgery is necessary.

The tendons can be repaired by stitching. If they are severely torn, they need to be replaced with new tendon tissue. Sometimes this tendon tissue can be obtained from the same leg. At other times allograft tendons are used. These come from the cadaver bank. The allograft tendons are safe to use, have no immunogenic properties and are not rejected. This procedure has been successfully performed on professional athletes who have returned to national level competition.

The peroneal tendons are shown on the left, where they lie behind the fibula bone behind the outside of the ankle. On the right, you can see a large tear in the tendon.