A tendon is a band of tissue that connects a muscle to a bone. In the foot, there are two peroneal tendons. They run side-by-side behind the outer ankle bone. One tendon, the peroneus brevis attaches to the outer part of the midfoot, while the other tendon, the peroneus longus, runs under the foot and attaches near the inside of the arch. The main function of the peroneal tendons is to stabilize the foot and ankle and protect them from sprains.
Peroneal tendon injuries may be acute (occurring suddenly) or chronic (developing over a period of time). They most commonly occur in individuals who participate in sports that involve repetitive ankle motion. In addition, people with higher arches are at risk for developing peroneal tendon injuries. The following are the three basic types of peroneal tendon injuries:
Tendonitis is an inflammation of one or both tendons. The inflammation is caused by activities involving repetitive use of the tendon, overuse of the tendon or trauma (such as an ankle sprain). Symptoms of tendonitis include:
- Warmth to the touch
Acute tears are caused by repetitive activity or trauma. Immediate symptoms of acute tears include:
- Weakness or instability of the foot and ankle
As time goes on, these tears may lead to a change in the shape of the foot, in which the arch may become higher.
Degenerative tears (tendonosis) are usually due to overuse and occur over long periods of time—often years. In degenerative tears, the tendon is like taffy that has been overstretched until it becomes thin and eventually frays. Having high arches also puts you at risk for developing a degenerative tear. The signs and symptoms of degenerative tears may include:
- Sporadic pain (occurring from time to time) on the outside of the ankle
- Weakness or instability in the ankle
- An increase in the height of the arch
Subluxation occurs when one or both tendons have slipped out of their normal position. In some cases, subluxation is due to a condition in which a person is born with a variation in the shape of the bone or muscle. In other cases, subluxation occurs following trauma, such as an ankle sprain. Damage or injury to the tissues that stabilize the tendons (retinaculum) can lead to chronic tendon subluxation. The symptoms of subluxation may include:
- A snapping feeling of the tendon around the ankle bone.
- Sporadic pain behind the outside ankle bone.
- Ankle instability or weakness.
Early treatment of a subluxation is critical, since a tendon that continues to sublux (move out of position) is more likely to tear or rupture.
Because peroneal tendon injuries are sometimes misdiagnosed and may worsen without proper treatment, prompt evaluation is advised. To diagnose a peroneal tendon injury, the surgeon will examine the foot and look for pain, instability, swelling, warmth and weakness on the outer side of the ankle. In addition, imaging studies such as an MRI or ultrasound may be needed to fully evaluate the injury.
An ankle sprain may sometimes accompany a peroneal tendon injury. The surgeon is trained to look for signs of this and other related injuries. Proper diagnosis is important because prolonged discomfort after a simple sprain may be a sign of additional problems.
Treatment depends on the type of peroneal tendon injury, however, most can be treated non-operatively thru:
- Immobilization - A cast or splint may be used to keep the foot and ankle from moving and allow the injury to heal.
- Medications - Oral or injected anti-inflammatory drugs may help relieve the pain and inflammation.
- Physical therapy - Ice, heat or ultrasound therapy may be used to reduce swelling and pain. As symptoms improve, exercises can be added to strengthen the muscles and improve range of motion and balance.
- Bracing - The surgeon may provide a brace to use for a short while or during activities requiring repetitive ankle motion. Bracing may also be an option when a patient is not a candidate for surgery.
Surgery may be warranted to repair the tendon if non-operative measures fail. The type of surgery depends on what kind of tendon problem the patient has as well as the patient’s condition and lifestyle. After surgery, physical therapy is an important part of rehabilitation. Surgery may be recommended as a first line of treatment particularly if the patient has suffered a tendon subluxation.