Wow! This week I had the worst chronic peroneal tendon rupture I have ever seen! My patient had sustained an “ankle sprain” about two years ago and wondered why her ankle looked more like a “cankle” two years later. She had a large lump just behind her fibular malleolus (a.k.a. the bone on the outside of your ankle). She noticed swelling on and off, but it never really went down all the way. She also had intermittent pain and felt like her ankle was unstable. Like most women with several children, she ignored it until it really became a lifestyle issue. She felt like she couldn’t exercise at all because her ankle felt so unstable.

Peroneal tendon injuries often occur with ankle sprains and are commonly overlooked until your ankle pain becomes chronic. The peroneal tendons stabilize the outside of your foot and ankle and allow you to turn your foot outward. There are two tendons which run side by side, behind your outer ankle bone, then split in the foot; one to the outside while the larger one dives under your foot and inserts in the arch just behind your big toe joint.

People with high-arched feet are more likely to experience peroneal tendon injuries.

Peroneal tendon injuries fall into three categories: tendonitis, tears, and subluxation. They are more common in active, athletic patients and can be acute (sudden) or chronic (lingering) in nature.

Tendonitis is inflammation, acute tears are caused by an injury and tendonosis (chronic tears) are usually caused by overuse and repetitive stress or chronic tendonitis. Subluxation usually occurs in an acute injury, like an ankle sprain, where the tendons actually dislocate onto the outer ankle bone and snap back and forth with activity.

The symptoms of a peroneal tendon injury can include swelling, pain, warmth, weakness and instability of the foot and ankle. Subluxation can also include a snapping feeling and sporadic pain with activity.

Treatment of peroneal tendon injuries is often delayed by misdiagnosis. If you are experiencing any of the symptoms of a peroneal injury, seek medical attention from a foot and ankle surgeon urgently. The longer the tendons go untreated, the more damage occurs. X-rays and physical examination usually lead to an MRI to solidify the diagnosis.

My patient’s MRI showed a severe rupture of peroneus brevis with a bulbous scar tissue formation which you can see in the below picture. Peroneus longus was normal.

Treatment include rest, casting, functional orthotics, anti-inflammatory medication or injection therapy, physical therapy, bracing, and in some cases surgery. Obviously, my patient needed a repair. We excised the torn and hypertrophied part of the tendon, then repaired the rest and fixed her ligaments so she would stop being so unstable and finally lose her “cankle”.


Here is the piece of abnormal tendon we excised. Wow! Big chunk!!



Your disability from a peroneal tendon injury can be significantly reduced by early intervention, so if you are experiencing any of these symptoms, call or contact the office and be evaluated. The sooner you have a proper diagnosis, the faster you will return to normal activity levels pain-free. If my patient had come in earlier to have her “ankle sprain” evaluated, conservative therapy might have healed her tendon injury!