Peroneal Tendon Repair & Groove Deepening

Indication. Symptomatic peroneal tendon pathology — recurrent subluxation or dislocation with documented superior peroneal retinaculum (SPR) insufficiency, or a symptomatic longitudinal tendon tear — that has failed conservative management (physiotherapy with peroneal strengthening and proprioception, bracing, activity modification and at least one injection) over 3–6 months. In high-demand athletes and military personnel, an acute complete SPR rupture or an acute dislocation with a bony avulsion is usually managed operatively from the outset because non-operative treatment carries a high redislocation rate. Absolute indications

• Recurrent peroneal tendon subluxation or dislocation with documented SPR insufficiency
• Symptomatic longitudinal peroneal tendon tear greater than 50% width after failed conservative management
• Acute complete SPR rupture in a high-demand athlete or military personnel
• Peroneal tendon dislocation with an associated avulsion fracture requiring fixation Relative indications
• Chronic peroneal tenosynovitis refractory to conservative treatment
• A tendon tear less than 50% width with mechanical symptoms
• A shallow retromalleolar groove (less than 5 mm depth) with symptomatic subluxation
• Failure of prior conservative management: physiotherapy, bracing, activity modification, injections Contraindications. Absolute: active infection overlying the surgical site; severe peripheral vascular disease with inadequate perfusion; medical comorbidities prohibiting surgery. Relative: uncontrolled diabetes with poor wound-healing potential; heavy tobacco use; poor patient compliance with post-operative restrictions; significant ankle arthritis requiring a different approach; a neuropathic (Charcot) ankle. Pre-operative assessment. Clinically, look for swelling posterior to the lateral malleolus, ecchymosis and a visible or palpable subluxation; palpate for tendon tenderness and reproduce subluxation with circumduction (dorsiflexion plus eversion reproduces the snap, and resisted eversion is painful). Assess associated lateral ligament injury (anterior drawer, talar tilt) and test function (single-leg heel raise, toe-walking) and lateral foot sensation in the sural distribution. Image with weight-bearing AP, lateral and mortise ankle plus AP and lateral foot radiographs (look for the os peroneum and avulsion fractures); an MRI is critical — axial sequences assess tendon tears, tenosynovitis, SPR integrity and groove depth; ultrasound gives a dynamic real-time view of subluxation (operator-dependent); and a CT is used to measure retromalleolar groove depth when deepening is contemplated (less than 5 mm is shallow). Key MRI findings are T2 hyperintensity (tendinosis), a longitudinal split (the tram-track sign), a torn or attenuated SPR, a flat or convex groove, and any ankle effusion, lateral malleolar marrow oedema or os peroneum. Match the operation to the pathology. The single most important decision is whether the groove needs deepening at all — it usually does not.

Setup & positioning. Position lateral decubitus with the affected side up (preferred — gravity assists exposure and optimal visualisation) or supine with a bump under the ipsilateral hip (easier anaesthesia access). Apply a thigh tourniquet to 250–300 mmHg and pad all bony prominences (add an axillary roll if lateral). Consent specifically for sural nerve injury or a painful neuroma, wound complications from the thin lateral skin, recurrent subluxation from an inadequate SPR repair, residual eversion weakness, and ankle stiffness.

The goal: expose the tendons through the lateral approach posterior to the fibula, identify and protect the sural nerve, repair any tendon tear, selectively deepen a flat or convex groove, and then — the indispensable step — reconstruct the SPR so the tendons track stably through full range of motion. The exposure is laid out in full as the first steps below (and in depth on the approach to the posterior tibial and peroneal tendons page).

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SPR repair — three options. Pick by tissue quality; whichever you choose, repair with the ankle in neutral dorsiflexion and slight eversion.

Rehabilitation | Phase | Timing | Weight-bearing & immobilisation | Therapy focus | |-------|--------|----------------------------------|---------------| | 1 | 0–2 weeks | Short-leg splint or CAM boot in slight eversion and neutral dorsiflexion; non-weight-bearing with crutches | Elevation, ice and ankle pumps of the non-operative joints; multimodal analgesia; DVT prophylaxis if high-risk; sutures out at 10–14 days | | 2 | 2–6 weeks | Tendon-repair-only: begin partial weight-bearing at week 2–3; groove deepening: non-weight-bearing to week 4; progress 25% body weight per week | Gentle active-assisted ROM from week 4 (plantar/dorsiflexion in the boot); avoid inversion; start with a 10–15° arc | | 3 | 6–12 weeks | Full weight-bearing in the boot by week 6; wean to a supportive shoe by week 8 if ROM is adequate and pain controlled | Progressive active ROM in all planes (full dorsiflexion/plantarflexion by week 8); isometric then resistance-band peroneal strengthening; proprioception from week 8 | | 4 | 3–6 months | Lace-up ankle brace for sport initially (3–6 months), weaned as confidence builds | Plyometrics, cutting and figure-8 drills, sport-specific training; return to sport at 4–6 months once peroneal strength is greater than 85% and the single-leg hop is greater than 90% of the other side | Good-to-excellent results are reported in the large majority after anatomic SPR repair, with the AOFAS hindfoot score typically improving from the high 50s into the low 90s (Cho 2014, Raikin 2009, Hu and Xu 2018). A minority have residual symptoms (mild pain, scar tenderness, subjective instability), and most athletes return to sport around 3–6 months depending on the procedure performed. Complications

Risk-factor mitigation. Patient factors driving wound and nerve complications include diabetes (wound complications around 15% versus 5%), smoking (around 12% versus 5%), obesity, neuropathy and prior lateral ankle surgery (which roughly doubles the sural nerve injury risk). The surgical drivers of failure are an inadequate SPR repair, a poorly placed incision (too posterior risks the nerve, too anterior compromises exposure), perforation or fracture from excessive groove deepening, and a haematoma from poor hemostasis. Red flags requiring urgent assessment

• Sudden increase in pain with swelling — fracture, DVT or infection
• Fever, wound drainage or increasing erythema — infection
• A palpable or visible tendon subluxation — repair failure
• Disproportionate pain, colour changes or allodynia — CRPS
• Calf swelling, tenderness or a positive Homan sign — DVT
• Worsening numbness or paraesthesia — nerve injury Follow-up
• 6 weeks — clinical review plus radiographs if groove deepening was performed
• 3 months — assess ROM and strength; plan return to activity
• 6 months — functional assessment and return-to-sport clearance
• 1 year — final outcome assessment and patient satisfaction

Pathoanatomy. Peroneal tendon disorders — tendinosis, longitudinal tears, subluxation or dislocation, and a painful os peroneum — are strongly associated with hindfoot varus, chronic lateral ligament instability, an enlarged peroneal tubercle and a low-lying peroneus brevis muscle belly, all of which should be sought and corrected to prevent recurrence (Roster 2015). In the retromalleolar groove the brevis sits anterior and the longus posterior; the brevis is compressed between the longus and the fibula, which is why it carries the classic C-shaped longitudinal split. The superior peroneal retinaculum is the primary restraint, running from the posterior fibular ridge to the lateral calcaneus, and a flat or convex retromalleolar groove reduces the bony buttress and predisposes to subluxation. Eckert-Davis classification of acute SPR injury. Acute injury is graded by the integrity of the SPR and its fibular attachment — the lesion you must address at operation.

Intrasheath subluxation. Raikin (2009) defined intrasheath subluxation — painful snapping with an INTACT retinaculum, missed on static imaging and diagnosed on dynamic ultrasound. Type A: the tendons switch their relative position within the sheath; Type B: the longus subluxes through a longitudinal split in the brevis. Of his 14 patients, 13 had a convex (not concave) groove intra-operatively, and this is the one clear indication in which groove deepening (with retinacular reefing) is the primary corrective step. What the evidence actually shows

• The SPR is the indispensable restraint. Anatomic SPR repair or reattachment alone gives good-to-excellent results and low recurrence (Cho 2014, Park 2021); the older claim that groove deepening alone is curative is not supported.
• Groove deepening is an adjunct, not a default — indicated chiefly for a flat or convex (shallow) groove, or for intrasheath subluxation with a convex groove (Raikin 2009). Adding it to SPR repair did not improve scores in the one comparative trial and lengthened operating time (Cho 2014).
• Concomitant tears need an algorithm, not a single technique (Redfern and Myerson 2004), and coexisting hindfoot varus, lateral instability or a prominent peroneal tubercle must be corrected (Roster 2015). Outcome benchmarks. The AOFAS hindfoot score typically improves from the high 50s pre-operatively into the low 90s post-operatively (Cho 2014, Raikin 2009, Hu and Xu 2018). Recurrent dislocation after anatomic SPR repair is low (single-digit percentages in the reattachment series), and most failures are re-injuries (Park 2021). Sural nerve symptoms are the most frequently reported complication and are usually a transient neuropraxia (Park 2021, Roster 2015). Guidelines, registries & global practice
• No high-level society guideline (AAOS, BOA/BOFAS, AOFAS, EFORT) mandates a single technique, and there is no implant registry for this soft-tissue procedure; practice follows the evidence above.
• Groove deepening, yes or no — many UK/European (BOFAS-aligned) and Asian centres favour SPR repair alone for a normal-depth groove and reserve deepening for a flat or convex groove, while some North American practice deepens more liberally. The comparative evidence (Cho 2014) supports the selective approach.
• Open versus tendoscopic deepening — tendoscopic deepening and SPR procedures are increasingly used in specialist centres; reported outcomes are comparable but the evidence remains lower level.
• Acute primary repair — for an acute Eckert-Davis grade injury in a high-demand athlete, early operative repair is widely favoured over non-operative cast treatment because non-operative management carries a high redislocation rate.