Skip to main content

Health condition · Clinically reviewed

Peroneal tendon dislocation, the classic snapping ankle — from bracing to groove-deepening with retinacular repair.

Traumatic or recurrent dislocation of the peroneal tendons from behind the lateral malleolus — a commonly missed lateral-ankle injury. Modern stratified care: bracing for acute injury; surgical retinaculum repair and groove-deepening for recurrent dislocation.

Jump to treatment See red-flag ankle signs
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Every claim is checked against BOFAS, NICE and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects current UK guidance on bracing, dynamic ultrasound and fibular groove-deepening surgery.

Key facts

Peroneal tendon dislocation at a glance.

The essentials, in plain English — what peroneal tendon dislocation is, why it snaps behind the outer ankle, and what a proper diagnosis and repair actually involve.

  • Definition

    Peroneal tendon dislocation is displacement of the peroneus longus and brevis tendons from behind the lateral malleolus (fibula).

  • Commonly missed

    Often mistaken for an ordinary lateral ankle sprain — the snapping sensation is the clue that something more is going on.

  • Eckert-Davis grading

    Injury of the superior peroneal retinaculum is classified by the Eckert-Davis system — it guides whether repair or reconstruction is needed.

  • Dynamic ultrasound

    Dynamic ultrasound of the ankle is the diagnostic gold-standard — it can actually visualise the tendon subluxing in real time.

  • MRI role

    MRI confirms retinaculum injury and any coexisting tendon tear — essential planning for surgical decisions.

  • Groove-deepening

    For recurrent dislocation, fibular groove-deepening combined with retinaculum repair is the modern reference operation.

Why this guide matters

The snapping ankle nobody names.

Peroneal tendon dislocation is regularly missed for months or years — this guide sets out what to look for and what modern care actually looks like.

  • A snap is not a sprain

    Any snapping or clicking behind the outer ankle deserves specific assessment — it is not just a bad sprain.

  • Dynamic ultrasound is decisive

    It visualises the tendons subluxing in real time — a static scan can miss the diagnosis entirely.

  • Recurrent dislocation is a surgical problem

    Bracing rarely holds recurrent dislocation — fibular groove-deepening and retinacular repair are the durable answer.

How the diagnosis is made

From snapping ankle to a clear plan.

The steps a UK foot and ankle team will normally follow, in order — so you know what to expect and why.

  1. 01

    Recognising

    Trauma or sport history

    A twisting ankle injury, often with a snapping or popping sensation behind the fibula — classic in football, skiing and ballet.

  2. 02

    Recognising

    Palpation posterior to lateral malleolus

    Focal tenderness immediately behind the fibula — different from the anterior talofibular ligament of a typical sprain.

  3. 03

    Recognising

    Provocative eversion test

    Resisted eversion with the ankle in dorsiflexion can reproduce dislocation and the audible snap.

  4. 04

    Confirming

    Dynamic ultrasound of the ankle

    The gold-standard test — visualises the tendons subluxing over the fibula in real time during eversion.

  5. 05

    Confirming

    MRI ankle

    Assesses the superior peroneal retinaculum, tendon integrity and any longitudinal split of peroneus brevis.

  6. 06

    Managing

    Assess for coexisting cavus foot

    A high-arched cavus foot loads the peroneals and drives recurrence — it must be recognised and addressed.

  7. 07

    Managing

    Foot & ankle surgery consultation

    For confirmed recurrent dislocation, referral to a specialist foot and ankle surgeon for definitive care.

Typical timeline: 2–6 weeks from first appointment to a definitive plan.

Symptoms

What peroneal tendon dislocation actually feels like.

The story is telling — a twisting ankle injury with an audible snap behind the fibula, followed by recurrent snapping, clicking and a wobbly, unreliable ankle.

  • Snapping ankle

    The classic symptom — an audible or palpable snap behind the outer ankle during eversion or push-off.

  • Lateral ankle pain

    Pain focused behind the fibula rather than at the front of the ankle — different from a routine sprain.

  • Clicking / catching

    A clicking or catching sensation as the tendons roll over the lateral malleolus with movement.

  • Local swelling

    Swelling and tenderness posterior to the lateral malleolus, often mistaken for ligament sprain oedema.

  • Feeling of instability

    A sensation of the ankle giving way, particularly on uneven ground or when pushing off the foot.

  • Behind-fibula tendon subluxation

    Visible or palpable tendon movement out of its groove during active eversion of the foot.

  • Recurrent dislocation

    Repeated episodes of the tendons popping in and out — the strongest indication for surgical stabilisation.

  • Red flag

    Acute traumatic dislocation with a peroneal tendon tear needs urgent foot and ankle surgical review.

Treatment

How peroneal tendon dislocation is treated in the UK.

A stratified approach — casting and rehab for a first acute injury, and definitive surgical repair with fibular groove-deepening for recurrent dislocation.

  • Below-knee cast (acute non-displaced)

    For a first acute injury without displaced tendons — 4–6 weeks of immobilisation in a below-knee cast, foot slightly plantarflexed and inverted.

  • Ankle brace

    A supportive lace-up or semi-rigid ankle brace during rehab and return to sport — helps control eversion and reassures the joint.

  • Physiotherapy

    Peroneal strengthening, proprioception and balance work — the backbone of both non-operative and post-operative rehab.

  • Activity modification

    Temporary avoidance of high-risk pivoting sports while the retinaculum heals — a common-sense first-line measure.

  • Ultrasound-guided injection (peritendinous)

    Selective peritendinous injection for coexisting peroneal tendinopathy — used cautiously and always image-guided.

  • Fibular groove-deepening

    The modern reference operation for recurrent dislocation — the shallow fibular groove is surgically deepened to house the tendons securely.

  • Superior peroneal retinaculum repair

    Direct repair of the torn superior peroneal retinaculum — usually combined with groove-deepening for durable stability.

  • Anatomic retinaculum reconstruction

    Where the retinaculum is attritional or previously failed, reconstruction using local tissue or tendon graft restores the anatomy.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, physiotherapist or foot and ankle team knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • British Orthopaedic Foot and Ankle Society (BOFAS). Clinical standards for lateral ankle pathology.

  • NICE MSK guidance. Assessment and management of ankle injuries.

  • American Orthopaedic Foot & Ankle Society (AOFAS). Peroneal tendon disorders — clinical guidance.

  • Eckert WR, Davis EA. Acute rupture of the peroneal retinaculum — the Eckert-Davis classification.

Red flags

When a snapping ankle needs specialist review.

Most peroneal tendon dislocations do well with the right diagnosis and stratified care. These are the situations that need extra vigilance.

  • Missed dislocation as sprain

    A snapping sensation dismissed as an ordinary sprain — recurrent dislocation risk is high without appropriate diagnosis.

  • Concurrent peroneus brevis tear

    A longitudinal split of peroneus brevis often accompanies dislocation — needs MRI and surgical planning.

  • Recurrent dislocation

    Repeated episodes despite bracing — a clear indication for surgical stabilisation with groove-deepening and repair.

  • Post-op sural nerve injury

    New numbness or altered sensation on the outer border of the foot after surgery — needs surgical review.

  • Post-op wound complication

    Redness, discharge or wound breakdown after surgery — same-day contact with the surgical team.

  • Post-op re-dislocation

    Recurrent snapping after surgery suggests failed retinaculum repair or an insufficiently deepened groove — needs re-assessment.

  • Cavus foot with recurrent dislocation

    A high-arched cavus foot drives recurrence — must be identified and often needs a corrective osteotomy alongside soft-tissue repair.

  • Chronic ankle instability

    Coexisting lateral ligament instability is common — needs to be addressed at the same operation to prevent failure.

  • Post-op stiffness

    Persistent post-operative stiffness limiting rehab — early physiotherapy escalation and, if needed, surgical review.

Living with it

A treatable injury, with the right diagnosis.

Four things that make the biggest difference — targeted rehab, bracing, gradual return to sport, and early review of any recurrent symptoms.

A quiet reminder

A snap behind the ankle is a signal, not a nuisance.

Recurrent snapping is the clearest sign the retinaculum has not healed — early review saves years of low-grade damage.

  1. 01 Rehab

    Commit to peroneal strength work

    Progressive eversion strengthening and balance training — done consistently, it protects the repair and reduces recurrence.

  2. 02 Bracing

    Use a brace for return to sport

    A supportive brace during the return-to-sport phase reassures the ankle and reduces the risk of a repeat dislocation.

  3. 03 Load

    Progress activity gradually

    A graded return to pivoting sports over months, not weeks — the retinaculum and tendons need time to remodel.

  4. 04 Reviews

    Reassess if symptoms return

    Any recurrent snap, click or instability warrants review — early recognition prevents years of low-grade damage.

Frequently asked

Everything we get asked about peroneal tendon dislocation.

Quick answers on diagnosis, imaging, bracing, groove-deepening surgery and when to seek help.

  • What actually causes peroneal tendon dislocation?

    An acute injury — usually a forceful dorsiflexion with contraction of the peroneal muscles — tears the superior peroneal retinaculum that normally holds the tendons in a groove behind the fibula. Once torn, the tendons can slip out of place, often repeatedly.

  • Why is it so often missed?

    It is regularly mistaken for a lateral ankle sprain because the mechanism and swelling look similar. The clue is the snapping or clicking sensation behind the outer ankle — and focal tenderness behind, rather than in front of, the fibula.

  • Do I need a scan?

    Yes, if peroneal tendon dislocation is suspected. Dynamic ultrasound is the gold-standard test because it visualises the tendons subluxing in real time. MRI is complementary and assesses the retinaculum and any tendon tear.

  • Can it be treated without surgery?

    A first acute injury with the tendons back in place can be managed with a below-knee cast for 4–6 weeks and structured rehab. Recurrent dislocations, however, generally need surgery — bracing rarely holds them long-term.

  • What is fibular groove-deepening?

    A surgical procedure to deepen the shallow bony groove behind the fibula so the peroneal tendons sit more securely. Combined with repair or reconstruction of the superior peroneal retinaculum, it is the modern reference operation for recurrent dislocation.

  • What is the red flag I should not ignore?

    An acute traumatic dislocation with a suspected peroneal tendon tear — sudden severe lateral ankle pain, marked swelling and a visible or palpable tendon out of place — needs urgent foot and ankle surgical review.

Related content

Keep reading.

WhatsApp Call us

Nearby in the library

More conditions to explore

Browse all →
Pulse Healthcare concierge

Send us your enquiry

A concierge service for UK private healthcare. We match you with the best vetted clinics and consultants in our network - they then contact you directly.

So we can match you to the right clinician close to you.

Confidential. We respond within one working day.