The peroneal tendons connect the muscles on the outside of the lower leg with the outside of the foot. These tendons can cause ankle problems through inflammation, tearing, and instability. How do peroneal tendons cause ankle problems? Learn about these tendons and associated conditions and what you should do about them.

What are the peroneal tendons?

peroneal tendon anatomy

The peroneal tendons arise from the muscles contained on the outside of the lower leg. The tendons form into two tendons just above the ankle – peroneus longus and peroneus brevis. The tendons course on the outside of the ankle and insert onto the foot. In general, the action of the peroneus muscles and tendons is to evert the foot – ie moving the foot in an outward motion.

The peroneal tendons are closely related and in fact, sit on top of each other behind the fibula bone. This close relationship is part of the reason why we see so many problems with these tendons. The tendons can rub together causing inflammation.

How does a peroneal tendon cause ankle problems?

The peroneal tendons can be damaged by an acute injury such as an ankle sprain or a gradual repetitive injury. The tendons can be inflamed, torn, or unstable. It is important to get an assessment to find out the exact cause of the peroneal problem as treatments are often different.

Peroneal tendonitis

peroneal tendonitis on ultrasound

This is the most common problem when the tendons inflame just behind the fibula bone at the ankle joint. Most cases are caused by overuse. Typical symptoms include pain and swelling behind the ankle bone. Generally, the tendons are tender to touch and stretching of the tendons by rolling the foot inwards usually causes pain.

Imaging such as ultrasound and MRI can diagnose the condition.

Simple treatments such as ice, compression, and anti-inflammatory tablets will reduce swelling. Physiotherapy to strengthen the tendons, calf muscles, and small muscles of the foot will help. Shoe selection and orthotics can reduce forces on the tendons and help with the pain. Finally, a cotisone shot into the tendon sheath helps with more difficult cases. It is important that we do this injection with ultrasound guidance to make sure the cortisone is injected into the tendon sheath rather than the tendon.

Peroneal tendon tear

While less common than tendonitis, peroneal tendon tears can occur. Moreover, they are more likely to occur in the peroneus brevis tendon.

Tears occur for two reasons. First, the blood supply to the peroneus brevis is different throughout the tendon. In the area near the fibula bone, the blood supply is the poorest reducing healing potential. Second, the peroneus brevis tendon wedges between the peroneus longus and the bone as it wraps around the fibula. This leads to rubbing, friction, and potential tearing.

Overall, we treat tears the same as tendonitis. Physical therapy for a peroneal tendon tear is important. However, we tend to avoid cortisone injections due to the risk of worsening a tear. In these cases, we would consider other injections such as platelet-rich plasma or PRP. Finally, peroneal tendon tear surgery is an option to repair the tear or suture the tendon to the other normal tendon.

Peroneal tendon dislocation

Usually, this condition occurs after an ankle sprain. In most cases, the peroneal sheath keeping the tendons in place behind the fibula bone is torn. This results in the tendons being ripped out of their groove resulting in severe pain, clicking or locking. Sometimes, the tendons remain outside their groove.

Most doctors use ultrasound to visualise the peroneal tendon dislocation moving out of the groove. The video below shows a rarer type of dislocation where the tendons switch positions in the groove

Generally, these peroneal tendon dislocation cases require surgery to repair to sheath and increase the depth of the groove.

Final word from Sportdoctorlondon on peroneal tendon problems

The peroneal tendons hug the outside of the ankle. They can swell tear or dislocate. It is important to diagnose the peroneal tendon problem and treat it quickly.

Other foot and ankle conditions:

Dr. Masci is a specialist sport doctor in London. 

He specialises in muscle, tendon and joint injuries.

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