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

What Is Peroneal Tendon Subluxation?

Peroneal tendon subluxation occurs when one or both peroneal tendons — the peroneus longus and peroneus brevis — slip out of the groove behind the lateral malleolus (the bony bump on the outside of the ankle). Instead of staying within their fibro-osseous tunnel, the tendons pop anteriorly over the malleolus, creating the characteristic snapping or clunking sensation that patients describe.

This condition is frequently underdiagnosed because it is often mistaken for a lateral ankle sprain. Many patients sustain the original injury during an ankle inversion event and are treated for a sprain, only to develop persistent lateral ankle instability and snapping that does not resolve with conventional sprain treatment.

Anatomy: Why the Tendons Dislocate

The peroneal tendons normally run behind the fibula in a groove stabilized by the superior peroneal retinaculum (SPR) — a thick band of connective tissue that acts as a restraint. When the ankle is forcefully dorsiflexed combined with sudden peroneal muscle contraction (as in a ski fall or sudden deceleration), the SPR can avulse or tear, allowing the tendons to escape their groove.

In some patients, the fibular groove is anatomically shallow, creating a predisposition to subluxation even with minor trauma. These individuals may experience recurrent subluxation episodes starting in adolescence or young adulthood.

Symptoms of Peroneal Tendon Subluxation

The hallmark symptom is a palpable and often audible snap on the outer ankle during dorsiflexion and eversion — the same movement that occurs when pushing off in running or pivoting in sport. Many patients can reproduce the subluxation voluntarily by circling the ankle. Other symptoms include lateral ankle swelling, a feeling of giving way, and chronic outer ankle pain that is distinct from the ligament tenderness seen in classic sprains.

Diagnosis

Diagnosis begins with a clinical examination in which the physician attempts to reproduce the subluxation by placing the ankle through range of motion while palpating the peroneal tendons. Dynamic ultrasound — performed while the patient moves the ankle — can directly visualize tendon displacement in real time. MRI provides additional information about SPR integrity, associated peroneal tendon tears (particularly the peroneus brevis longitudinal split tear), and fibular groove morphology.

Treatment Options

Conservative Treatment for Acute Subluxation

Acute first-time subluxation in a young patient may be treated conservatively with six weeks of cast immobilization followed by progressive rehabilitation. The goal is to allow the avulsed SPR to scar down in an anatomic position. However, conservative treatment has a high recurrence rate — studies report 50 to 75 percent of patients treated nonoperatively experience ongoing instability. Surgical repair is generally recommended for athletes and for patients with recurrent episodes.

Surgical Repair: SPR Reconstruction

The most common surgical approach involves directly repairing or reconstructing the superior peroneal retinaculum through a small lateral incision. Anchors or sutures reattach the retinaculum to the fibula, restoring the restraining function. If the fibular groove is shallow, a groove-deepening procedure — rerostreplasty — is performed simultaneously by creating a trough in the posterior fibula to deepen the channel and prevent future subluxation.

Recovery after SPR repair typically involves six weeks of non-weight-bearing in a boot, followed by progressive rehabilitation over three to four months. Athletes typically return to sport between four and six months postoperatively.

Addressing Associated Peroneus Brevis Tears

A longitudinal split tear of the peroneus brevis tendon frequently accompanies subluxation. During surgery, the tendon is inspected through the same incision. Small tears are tubularized — the split edges are sutured together to restore tendon continuity. Larger tears involving more than 50 percent of the tendon may require tenodesis to the peroneus longus.

Outcomes and Return to Activity

Surgical outcomes for peroneal tendon subluxation are excellent, with the majority of patients achieving full return to sport and complete resolution of snapping. The key to good outcomes is accurate diagnosis — particularly distinguishing subluxation from lateral ligament instability, which requires different surgical repair. If you experience lateral ankle snapping, popping, or persistent outer ankle pain after an ankle injury, contact Balance Foot & Ankle for a comprehensive evaluation.

Expert Foot & Ankle Care in Michigan

Whether you’re dealing with chronic foot pain, a sports injury, or a complex deformity, Dr. Tom Biernacki provides evidence-based diagnosis and treatment at Balance Foot & Ankle in Howell and Bloomfield Hills.

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Clinical References

1. Thomas MJ, et al. “The population prevalence of foot and ankle pain in middle and old age: a systematic review.” Pain. 2011;152(12):2870-2880.
2. Garrow AP, et al. “The grading of hallux valgus: the Manchester Scale.” J Am Podiatr Med Assoc. 2001;91(2):74-78.
3. Riskowski JL, et al. “Measures of foot function, foot health, and foot pain.” Arthritis Care Res. 2011;63(S11):S229-S236.

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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.