The peroneal tendons connect the muscles on the outside of the lower leg to the outside of the foot. These tendons can cause ankle problems through tendonitis, tears, and instability. So how do the peroneal tendons cause ankle problems, and what should you do about them?
This is the overview page. For the most common problem in detail, see our dedicated page on peroneal tendonitis and how to treat it.
What are the peroneal tendons?
The peroneal tendons arise from the muscles on the outside of the lower leg. They form two tendons just above the ankle — the peroneus longus and the peroneus brevis — which run around the outside of the ankle and attach to the foot. Their main action is to evert the foot (turn it outward).
The two tendons sit close together, on top of each other, behind the fibula bone. This close relationship is why problems arise: the tendons can rub against each other, causing inflammation.
How do peroneal tendons cause ankle problems?
An acute injury, such as an ankle sprain, or gradual repetitive overload, can damage these tendons. They can become inflamed, torn, or unstable. An accurate assessment is essential to determine the exact problem, because the treatments differ.
Peroneal tendonitis
The most common problem is peroneal tendonitis — inflammation of the tendons just behind the fibula at the ankle, usually from overuse. Typical symptoms are pain and swelling behind the outer ankle bone, tenderness to touch, and pain when the tendons are stretched by rolling the foot inward. Ultrasound and MRI confirm the swelling.
Most cases settle with simple measures — ice, rest, anti-inflammatories, physiotherapy, and orthotics — with an ultrasound-guided cortisone injection for stubborn cases. Because this is the most common peroneal problem, we cover it in full on our peroneal tendonitis treatment page.
Peroneal tendon tears
Less common than tendonitis, peroneal tendon tears most often affect the peroneus brevis for two reasons. First, the blood supply to the peroneus brevis is poorest near the fibula, reducing its healing capacity. Second, the brevis is wedged between the peroneus longus and the bone as it wraps around the fibula, causing friction and potential tearing.
We generally treat peroneal tendon tears as we would tendonitis, with physiotherapy central to recovery. However, we avoid cortisone injections, which risk worsening a tear, and instead consider PRP. Peroneal tendon tear surgery is an option to repair the tear or stitch the tendon to the adjacent normal tendon.
Peroneal tendon subluxation and dislocation
Peroneal tendon subluxation and dislocation usually follow an ankle sprain. The sheath holding the tendons behind the fibula tears, allowing the tendons to slip out of their groove — causing severe pain, clicking, or locking. Sometimes the tendons stay out of their track.
Ultrasound is excellent here, showing the tendons moving out of the groove in real time. The video below shows a rarer type of dislocation in which the tendons switch positions within the track.
Subluxation or dislocation generally needs surgery to repair the sheath and deepen the groove.
[KEEP THE EXISTING VIDEO HERE — /wp-content/uploads/2021/04/My-Movie-1.mp4 — it’s genuine first-hand ultrasound footage and a strong E-E-A-T asset.]
Frequently asked questions about peroneal tendon problems
What does a peroneal tendon problem feel like?
Most cause pain and swelling on the outside of the ankle, behind the bony bump, worse with activity. Tears can feel similar to tendonitis; subluxation adds clicking, snapping, or a sense of the tendon slipping, often after an ankle sprain.
How do I know if it’s tendonitis or a tear?
You often can’t tell from symptoms alone — both cause outer-ankle pain and swelling. Ultrasound or MRI distinguishes them, which matters because a tear changes the treatment (we avoid cortisone and consider PRP or surgery).
Which peroneal tendon usually tears?
The peroneus brevis is prone to injury because of its poorer blood supply near the fibula and the friction from being wedged between the longus tendon and the bone.
Do peroneal tendon problems need surgery?
Most tendonitis and many tears settle without surgery. Surgery is mainly reserved for significant tears that fail conservative treatment, and for subluxation or dislocation, where the sheath needs repair and the groove deepening.
What’s the difference between this and os peroneum syndrome?
Os peroneum syndrome involves a small bone within the peroneus longus tendon, causing pain further forward in the outer mid-foot. It’s a related but distinct peroneal problem.
Final word from Sport Doctor London about peroneal tendon problems
The peroneal tendons run along the outer side of the ankle and can swell, tear, or dislocate. Diagnosing the specific problem is essential because treatments differ — and getting it right early yields the best outcome.
To book a one-stop ankle assessment with Dr Masci in London, contact the team here or call +44 (0) 203 488 0350.
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