Peroneal Tendon Tear

Overview

what it is and why it matters

Two tendons, the peroneals (peroneus brevis and peroneus longus), run together in a groove right behind the bony bump on the outside of your ankle. Their job is to roll your foot outward and stop your ankle from rolling inward. The most common injury is a lengthwise split in the peroneus brevis, right where it sits in that groove behind the ankle bone. It often comes along with a chronically loose ankle that's been sprained over and over. The classic clue: lateral ankle pain that just won't quit after what was supposed to be a routine ankle sprain.

Symptoms

what you may notice

Pain behind the outer ankle bone, a sharp or aching pain right behind the bony bump on the outside of your ankle, worse when you push off or change direction.
Swelling along the peroneal tendons, puffiness running down the groove behind the ankle bone toward the outside of your foot.
Ankle giving way, your ankle feels loose or buckles, especially on uneven ground.
Snapping or popping sensation, you feel (or even hear) the tendon flipping in and out of its groove when you roll your foot.
Lingering pain after a "healed" sprain, weeks or months after an ankle sprain, the outer ankle still hurts and isn't improving.

Diagnosis

exam first, imaging second

The diagnosis starts with a focused physical exam of the ankle, checking where the pain sits and how the tendons behave when the foot moves. An MRI is the definitive test, a split tendon shows up flattened or as two separate slips on the cross-section views. A live ultrasound (where the technician moves your foot during the scan) can also catch a tendon snapping in and out of its groove.

How We Treat It

what we try first, in order

For a partial tear, care starts conservatively and builds step by step. The idea is to take the load off the tendon long enough for it to settle, then rebuild the strength and balance that protect it. Each step is added on top of the one before, not instead of it.

Immobilization

The first step is a stretch of time in a cast or walking boot to take the load off the tendon while it settles down.

Physical Therapy

Once the tendon has calmed down, physical therapy takes over. It focuses on strengthening the muscles that pull your foot outward and on retraining your ankle's sense of balance, both of which take pressure off the healing tendon.

Surgical Options

if non-operative care isn't enough

Surgery is the answer when the tendon is split all the way through, when it keeps snapping out of its groove, or when months of bracing and rehab haven't quieted the pain.

Frequently Asked

questions we hear in clinic

Where exactly is a peroneal tendon tear?

The peroneal tendons, the peroneus brevis and peroneus longus, run together in a groove right behind the bony bump on the outside of your ankle. The most common injury is a lengthwise split in the peroneus brevis, right where it sits in that groove behind the ankle bone.

What do the peroneal tendons do?

They roll your foot outward and stop your ankle from rolling inward. That is why a tear shows up as pain on the outside of the ankle and a feeling that the ankle wants to give way.

Why does my ankle still hurt after a sprain that was supposed to heal?

A peroneal tendon tear often comes along with a chronically loose ankle that has been sprained over and over. The classic clue is lateral ankle pain that just won't quit after what was supposed to be a routine ankle sprain. If the outer ankle still hurts weeks or months later and isn't improving, the tendon is worth checking.

Will I need an MRI?

An MRI is the definitive test. A split tendon shows up flattened or as two separate slips on the cross-section views. A live ultrasound, where the technician moves your foot during the scan, can also catch a tendon snapping in and out of its groove.

Can a peroneal tendon tear be treated without surgery?

For a partial tear, yes. The first step is immobilization in a cast or walking boot to take the load off the tendon, followed by physical therapy that strengthens the muscles pulling your foot outward and retrains your ankle's balance.

When is surgery needed?