What is it: The peroneal tendon runs behind the lateral malleolus and partly attaches to the base of the fifth metatarsal. The peroneal tendon can be injured with a sprain, microtears or less commonly with a full thickness tear. This tendon can also sublux out of its normal location.
How does it present: Patients usually present with lateral ankle pain and perhaps swelling. If the tendon is subluxing, the patient may feel a "pop" in the ankle with dorsiflexion and eversion motions. The symptoms commonly start after an ankle twisting injury.
Common exam findings: The patient may present with tenderness along the peroneal tendon behind the lateral malleolus and there may be swelling present. If the tendon is subluxing, this may be appreciated manually by the examiner. In the case of more severe tears of the tendon, ecchymosis may also be present and patients may have some difficulty standing on their toes.
Tests and treatment: An ankle x-ray may be indicated if bony injury needs to be ruled out. The peroneal tendon can be visualized with musculoskeletal ultrasound or MRI if necessary. Treatment of tendonopathy includes conservative measures, support and functional rehabilitation. Full thickness tears or recurrent subluxation may require surgical intervention.