If you have clicking or snapping on the outside of the ankle after an injury—and it’s sharp, painful, and feels like something is “flicking” out of place—don’t let it be dismissed as simple tendinopathy.
One important cause is peroneal tendon subluxation. This means one (or both) of the peroneal tendons is slipping out of its normal groove behind the lateral malleolus (the bony bump on the outside of the ankle), then snapping back into place.
A common story: the scan shows one thing, the patient describes another
This often follows a twisting injury. The person may be told an MRI shows “peroneal tendinopathy” and is sent to physiotherapy. Rehab can help tendinopathy—but it won’t fix a mechanical problem if a tendon is physically subluxing.
The giveaway symptom is the one patients often describe clearly:
- Clicking, snapping, or flicking on the outside of the ankle
- Sudden, severe pain when it happens
- Symptoms triggered by certain movements, often dorsiflexion
- Ongoing fear of movement because it feels unstable
If the main complaint is painful snapping, the problem may be instability rather than inflammation.
Why dynamic ultrasound is the key test
Peroneal tendon subluxation is a movement problem. That’s why it can be missed if imaging is done at rest. Dynamic ultrasound allows the clinician to watch the tendons move while the patient reproduces the symptom.
During the scan, the patient is guided through movements such as dorsiflexion and plantarflexion. In subluxation, you may see a tendon (often the peroneus brevis) migrate forward (anteriorly) and then snap back into position.
This is not subtle when it’s present—and it matches what the patient feels.
What does it mean if the tendon is subluxing?
By definition, peroneal tendon subluxation usually involves injury to the structure that holds the tendons in place, often the superior peroneal retinaculum. If the retinaculum is torn or lax, the tendons can slip out of the groove.
That’s why persistent, painful subluxation is often referred for orthopaedic assessment. Conservative treatment can be tried in selected cases, but if symptoms are severe, ongoing, or clearly mechanical, surgical repair may be considered to restore stability.
Conservative management vs surgery
Treatment depends on severity, timing, and impact on function. Options may include:
- Activity modification and bracing during flare-ups
- Physiotherapy focusing on strength, control, and ankle mechanics
- Footwear adjustments and proprioceptive rehab
- Orthopaedic opinion when subluxation is confirmed and symptoms are significant
If symptoms are severe and reproducible with snapping, surgery may be discussed—particularly when the retinaculum is injured and instability is ongoing.
Bottom line
Persistent painful clicking on the outside of the ankle after a twisting injury is not something to ignore. If an MRI report says “tendinopathy” but your main symptom is snapping or flicking, ask whether peroneal tendon subluxation has been considered. Dynamic ultrasound is often the most direct way to confirm the diagnosis because it shows the tendons moving in real time.