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

Peroneal tendon subluxation occurs when the peroneus longus and brevis tendons slip out of the retromalleolar groove behind the lateral ankle — a condition frequently misdiagnosed as a lateral ankle sprain. Unlike a sprain, subluxation involves mechanical instability requiring specific targeted treatment rather than rest and bracing alone.

Anatomy of the Peroneal Tendons

The peroneus longus and peroneus brevis tendons run behind the lateral malleolus in a fibro-osseous tunnel retained by the superior peroneal retinaculum (SPR). The SPR is the primary static stabilizer preventing subluxation. A shallow or convex retromalleolar groove (present in 11–18% of individuals) predisposes to recurrent subluxation even after minor trauma.

Mechanism of Injury

Acute subluxation classically occurs with forceful dorsiflexion of an inverted foot — common in skiing, basketball, and soccer. The sudden peroneal muscle contraction against resistance tears or avulses the SPR, allowing the tendons to displace anteriorly over the lateral malleolus. Patients often hear or feel a “pop” and may initially be evaluated for lateral ankle sprain, delaying correct diagnosis by weeks to months.

Classification (Oden Classification)

Grade I injury involves SPR elevation from the fibula with periosteal stripping. Grade II involves avulsion of the fibular periosteum with a cortical rim fracture (“flake fracture”) visible on X-ray. Grade III involves avulsion of the posterior fibular cortex. Grade IV — the rarest — involves intrasubstance SPR tear. Grades I and II are most common and generally treated successfully with operative SPR repair.

Clinical Presentation and Diagnosis

Patients present with posterior lateral ankle pain, swelling, and a subjective sense of ankle instability or “popping.” On examination, reproducing subluxation with resisted eversion and dorsiflexion (the peroneal provocation test) is pathognomonic. MRI confirms SPR injury, characterizes tendon integrity, and identifies associated peroneus brevis longitudinal split tears — present in 33% of surgical cases. Weight-bearing radiographs may reveal a flake fracture at the fibular tip.

Conservative Treatment

Acute Grade I subluxation in reliable patients may be managed with 6 weeks of immobilization in a non-weight-bearing cast followed by functional rehabilitation. Recurrence rates with conservative management range from 40–70%, substantially higher than surgical outcomes. Chronic or recurrent subluxation has poor response to conservative care and generally requires surgical correction.

Surgical Treatment Options

SPR repair or reconstruction restores the primary restraint. In patients with a shallow retromalleolar groove, fibular groove deepening (retromalleolar groove deepening procedure) is performed concurrently to reduce recurrence risk. Concurrent peroneus brevis tear repair is performed when identified. Postoperative immobilization for 4–6 weeks is followed by progressive rehabilitation over 3–4 months. Return to sport averages 4–6 months with excellent long-term outcomes (>90% satisfaction in surgical series).

Expert Peroneal Tendon Care at Balance Foot & Ankle

Dr. Biernacki at Balance Foot & Ankle evaluates peroneal tendon subluxation with on-site MRI coordination and weight-bearing imaging at your first visit. Both conservative management protocols and surgical correction are available for all grades of injury. Call (810) 206-1402 for a same-week appointment.

Peroneal Tendon Subluxation Treatment in Michigan

Peroneal tendon subluxation causes a painful snapping sensation behind the outer ankle — often misdiagnosed as a chronic ankle sprain. Our podiatrists recognize this condition and offer both conservative stabilization and surgical repair.

Get Expert Peroneal Tendon Care → | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Eckert WR, Davis EA. “Acute Rupture of the Peroneal Retinaculum.” Journal of Bone and Joint Surgery. 1976;58(5):670-672.
2. Raikin SM, et al. “Peroneal Tendon Disorders.” Foot and Ankle Clinics. 2009;14(2):299-312.
3. Porter D, et al. “Peroneal Tendon Subluxation in Athletes.” American Journal of Sports Medicine. 2019;47(8):1984-1992.

Dr. Tom Biernacki, DPM

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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.