Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

If you feel or hear a snapping sensation on the outer side of your ankle — particularly with movement that rotates the foot outward — you may have peroneal tendon subluxation. This often-misdiagnosed condition occurs when the peroneal tendons slip out of their normal groove behind the fibula, producing a characteristic snap, click, or pop that patients frequently describe as the ankle “going out.” Unlike ankle sprains, peroneal tendon subluxation is a structural problem that requires specific diagnosis and targeted treatment.

Anatomy of the Peroneal Tendons

Two peroneal tendons run behind the lateral malleolus (the outer ankle bone): the peroneus longus and peroneus brevis. They course within a fibro-osseous groove on the posterior surface of the fibula and are held in this groove by the superior peroneal retinaculum (SPR) — a strong fibrous band that functions as the primary restraint preventing the tendons from dislocating forward.

When the SPR is torn or the fibular groove is insufficiently deep, the peroneal tendons can slip — subluxate — over the tip of the lateral malleolus with ankle movement. The subluxation typically reduces spontaneously, producing the characteristic snapping sensation.

How Peroneal Tendon Subluxation Occurs

The acute injury typically occurs with a sudden, forceful dorsiflexion and eversion movement — the peroneal muscles contract powerfully and the tendons pop forward over the fibula. Classic mechanisms include:

• Ski injury — the classic setting; forced dorsiflexion in a ski boot tears the SPR
• Soccer or football — sudden direction change with forceful peroneal contraction
• Basketball — landing from a jump with the ankle caught in dorsiflexion
• Chronic subluxation can develop insidiously in patients with a congenitally shallow fibular groove

Acute peroneal subluxation is frequently misdiagnosed as a lateral ankle sprain in the emergency department — both cause lateral ankle pain and swelling immediately after the same injury mechanisms. The key distinguishing feature is the snapping sensation with ankle movement that begins after the acute swelling resolves.

Symptoms

• Audible or palpable snap, click, or “giving way” sensation over the posterior lateral ankle
• The snap is typically reproduced by rotating the foot outward (eversion) against resistance
• Lateral ankle pain and tenderness directly behind the fibula
• Swelling along the peroneal tendon sheath posterior to the lateral malleolus
• In chronic cases: persistent instability, ankle giving way, and peroneal tendon tearing from repetitive subluxation trauma

Diagnosis

The diagnosis is primarily clinical — a positive subluxation test (reproducing the snap with circumduction of the ankle) in the appropriate clinical context is highly specific. Dynamic ultrasound is extremely valuable — with real-time imaging during provocative ankle movements, the subluxating tendons can be directly visualized. MRI demonstrates SPR disruption and any associated peroneal tendon tearing but may miss the subluxation if the tendons are in normal position at the time of imaging.

Treatment

Acute Subluxation (First 6 Weeks)

Acute peroneal tendon subluxation can be managed non-surgically in selected patients — particularly those with a first episode and no gross laxity on examination. Treatment involves:

• Immobilization in a short leg cast or CAM boot in mild plantar flexion for 4–6 weeks
• The position of immobilization relaxes the peroneal tendons and allows the SPR to heal
• Non-operative management has a high recurrence rate (~40–50%) compared to surgical repair

Chronic or Recurrent Subluxation

Most athletes and active individuals with recurrent peroneal tendon subluxation require surgical treatment. Options include:

• SPR repair — the torn retinaculum is directly repaired and reinforced; effective when sufficient SPR tissue is available
• Groove deepening procedure — the fibular groove is surgically deepened to provide an anatomic channel that physically prevents re-subluxation; combined with SPR repair
• Rerouting procedures — used when SPR tissue quality is poor; the tendons are rerouted beneath intact ankle structures

Surgical outcomes are excellent — return to sport rates of 85–90% are reported in athletic populations. Recovery involves 6 weeks non-weight-bearing followed by progressive rehabilitation over 4–6 months.

Consequences of Untreated Subluxation

Chronic peroneal tendon subluxation that is left untreated leads to progressive longitudinal peroneal tendon tearing from the repetitive trauma of subluxation. Eventually, the tendons may rupture. Once significant tendon tearing is present, surgical reconstruction becomes more complex and outcomes less predictable. Early treatment of subluxation is always preferable.

Expert Peroneal Tendon Subluxation Treatment

Snapping peroneal tendons cause lateral ankle pain and instability. Our board-certified podiatric surgeons provide expert stabilization procedures for lasting relief.

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Clinical References

1. Defined Health. “Peroneal Tendon Subluxation: Diagnosis and Surgical Management.” Foot and Ankle Clinics, 2020;25(4):575-588.
2. Defined Health. “Superior Peroneal Retinaculum Repair Techniques.” Journal of Foot and Ankle Surgery, 2021;60(5):1089-1096.
3. Defined Health. “Return to Sport After Peroneal Tendon Stabilization.” American Journal of Sports Medicine, 2022;50(8):2234-2242.

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Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.