Peroneal Tendinopathy

Soft Tissue Conditions· Also known as: peroneal tendinitis, peroneal tendonitis, fibularis tendinopathyUpdated Oct 2026

Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPod, October 2026

At a Glance

Peroneal tendinopathy is pain and reduced strength in the peroneal tendons, two strong cords that run down the outside of your ankle. Doctors now see it as a significant cause of outer ankle pain in active people and after ankle sprains, although it was once thought to be rare. The main symptom is pain on the outer foot or just behind the outer ankle bone, which builds with activity and eases with rest. Care that doesn't involve surgery is the usual first step, and surgery is kept for cases that don't respond.

What is it?

Your peroneal tendons are two strong cords that run down the outside of your ankle. A tendon is a tough band that joins muscle to bone. These two help keep your ankle and foot steady, especially on uneven ground or when you stand on one leg.

Peroneal tendinopathy means pain and reduced strength in these tendons. It is thought to be mainly an overuse problem: small injuries to the tendon fibres happen faster than your body can repair them. You may also hear it called peroneal tendonitis or tendinitis.

Problems with these tendons fall into three groups: tendinopathy, a tear or rupture, and instability, where the tendon slips out of place. This page is mostly about the first. The other two matter because they can feel similar.

Who does it affect?

It is a significant cause of outer ankle pain in active people. It is also a serious cause of ongoing symptoms after an ankle sprain. Around 40 per cent of ankle sprains lead to long-lasting ankle pain, and peroneal tendinopathy is one possible cause.

It often follows a change in how much you do. That might be a sudden jump in activity, such as taking up running, or a long break from activity.

Signs and symptoms

The main symptom is pain on the outer side of your foot or just behind the outer ankle bone. Some people feel it above or below the ankle bone, or along the outer edge or arch of the foot. There can be swelling too, though the ankle often looks quite normal.

The pain usually comes on slowly and gets worse over time. It builds with walking, running and jumping, and eases with rest. Many people also feel it after sitting still and first thing in the morning. Rising up onto the ball of your foot can bring it on.

Some people feel unsteady on uneven ground, or find it harder to balance on the sore leg. You may notice that pushing outwards with your foot feels weaker than on the other side. Pain under the foot or higher up the leg is less typical.

What causes it?

Tendon problems usually start when your daily activity is more than your tendon can cope with. This can happen after a one-off injury such as an ankle sprain, or after a sudden increase in activity. It can also follow doing much less than usual, for example after an illness or a long rest, and then going back to normal activity. Walking or running on uneven ground in worn shoes can add to the strain.

Several other things are linked with it:

a past ankle sprain, foot or ankle injury, or foot or ankle surgery
foot shapes such as high arches or flat feet
a tight space behind the outer ankle bone, which can crowd the tendons
shoes that don't support your feet
carrying extra weight
smoking
long-term use of steroid tablets, or a group of antibiotics called fluoroquinolones

These are links, not proven causes. Having one doesn't mean you will get the problem.

How is it diagnosed?

Your podiatrist will ask where the pain is, when it comes on, and what has changed in your activity or footwear. They will also ask about past sprains, your ankle giving way, and the medicines you take. They will feel along the tendons, look for swelling, and compare both ankles. They may test how strongly you can push outwards with your foot and how well you balance on one leg.

No single test settles it. Other problems can cause similar pain, including a tendon tear, a tendon slipping out of place, and a small break in the bone at the outer ankle. Peroneal problems are also often mistaken for a simple sprain. Delayed or wrong diagnosis can let the problem progress to a tendon tear, and can limit how well treatment without surgery works. That is why outer ankle pain that lingers after a sprain is worth having checked.

Treatment

Care without surgery is the first choice for almost everyone. It isn't yet clear which exercises or programmes work best.

Looking after it at home

In the early days, rest, ice, compression and elevation (raising your foot) can help. For the first 4 to 6 weeks, avoid the activities that hurt most, and avoid running and jumping. Gentle, low-impact activity such as walking, swimming and cycling is usually fine, as long as you take care.

Total rest isn't the goal. Moving is generally better than lying still, and long periods of inactivity can irritate the tendon and weaken your muscles. Keeping the ankle held still (immobilisation) is generally best avoided.

When it is painless, start putting weight on the foot. Then add ankle movement exercises, and after that exercises that load the tendon.

Treatment from your podiatrist

Your podiatrist can check your ankle, help you adjust your activity, and guide your exercises so that you build up safely. If you haven't improved within 6 to 8 weeks of looking after it yourself, see your GP about a physiotherapy referral. If you are improving, even slowly, you can carry on with your plan for up to 3 months.

Other options

If your pain hasn't started to improve after 12 weeks, ask for further review by a specialist or a musculoskeletal service. They may suggest an ultrasound or MRI scan.

Steroid injections around the tendon are debated, because they carry a risk of the tendon rupturing. Talk through the benefits and risks with your clinician before agreeing. There isn't enough proof to support platelet-rich plasma injections (made from your own blood).

Surgery

Irritation of the peroneal tendons (peroneal tenosynovitis) usually settles with care that doesn't involve surgery. Surgery is kept for cases that don't respond.

Recovery

How long it takes to get better isn't clear, but expect weeks to months, not days. A steady, gradual plan matters more than rushing. Return to running and jumping slowly, and ease back if the pain builds up again.

Leaving it untreated can lead to pain that lasts and problems with everyday function. Poor diet, high cholesterol and diabetes are linked to a higher risk of tendon problems and slower healing in general. If you carry extra weight, losing some can ease the load on the tendon. Your GP can help with any of these.

Preventing it

It isn't yet clear what stops it coming back. Sensible steps follow from what is known about how it starts: build up running or new activities gradually, and wear shoes that support your feet. Replace worn shoes, especially if you walk or run on uneven ground.

When to see a podiatrist

Book an appointment if

Pain on the outside of your ankle or foot keeps building with activity, or it lingers after an ankle sprain: book an appointment with your podiatrist. You haven't improved after 6 to 8 weeks of looking after it yourself: see your GP about a physiotherapy referral. Your pain hasn't started to improve after 12 weeks of following the advice: see your podiatrist or GP for further review.

Seek prompt assessment if

Your leg, foot or toes suddenly turn cold and pale or blue, with pain or numbness, or you suddenly can't move your leg or foot: call your local emergency number. You feel a pop or snap, the tendon seems to slip out of place, you have sudden swelling and redness around the tendon (a tendon can tear), or your foot or ankle becomes hot, swollen and tender: see your GP or another doctor today. You have significant swelling, or a colour or temperature change that spreads up your leg, or signs of infection such as a high temperature, unusual night sweats or feeling unwell: see your GP or another doctor today. If your GP can't see you today, go to an urgent care clinic or an after-hours GP. You notice a new lump in your foot or ankle, or you are losing weight and can't explain why: see your GP soon. You still can't put weight on your foot one to two weeks after an injury, or your ankle is giving way more often: see your GP soon.

Frequently asked questions

Is it the same as a sprained ankle?

No. A sprain injures ligaments, while this is a problem in the tendons. The two can feel alike, and the peroneal tendons are often injured during a sprain. If pain on the outside of your ankle drags on after a sprain, ask your podiatrist to check the tendons.

Do I need an ultrasound or MRI?

Not always. Your podiatrist can often work out what is going on from your story and an examination. An ultrasound may show that the tendon is thickened. Scans are more likely to be suggested if you aren't improving, or if a tear or a break in the bone is suspected.

Should I stop a medicine that might be linked to this?

Don't stop a prescribed medicine on your own. Long-term steroid tablets and fluoroquinolone antibiotics have both been linked to tendon problems. Tell your podiatrist which medicines you take, and talk to the doctor who prescribed them about whether any changes are needed.

What if an exercise makes the pain worse?

Stop that exercise if the pain starts or increases, and ask your podiatrist or physiotherapist for advice. They can change the exercise or the amount you do. If you are struggling to manage the problem, contact your GP, who can arrange referral to musculoskeletal services if needed.