High-Yield Summary
- Chronic peroneal tendon subluxation results from superior peroneal retinaculum (SPR) injury or anatomical predisposition, causing lateral ankle pain and instability.
- Diagnosis hinges on dynamic clinical examination and imaging, with MRI and ultrasound critical for assessing tendon integrity and retinacular status.
- Surgical management is indicated for symptomatic chronic subluxation refractory to conservative care or with tendon pathology.
- The preferred surgical approach involves SPR repair or reconstruction combined with groove deepening to restore tendon stability.
- Meticulous soft tissue handling and intraoperative assessment of tendon excursion prevent recurrence and optimize functional outcomes.
Clinical Fundamentals
Anatomy:
The peroneal tendons (peroneus longus and brevis) course posterior to the lateral malleolus within a fibro-osseous tunnel formed by the fibula and the superior peroneal retinaculum (SPR). The SPR acts as a primary restraint preventing anterior subluxation of the tendons during ankle motion.
Biomechanics:
Peroneal tendons stabilize the lateral ankle and subtalar joint, facilitating eversion and plantarflexion. Disruption of the SPR or a shallow fibular groove alters tendon tracking, leading to subluxation or dislocation during dorsiflexion and eversion.
Epidemiology:
Chronic peroneal tendon subluxation is uncommon but underdiagnosed, often seen in athletes and individuals with repetitive ankle trauma or anatomical variants such as a flat or convex fibular groove.
Classification & Diagnosis
| Classification System | Description | Management Implication |
|---|---|---|
| Eckert and Davis Classification | Type I: SPR avulsion with periosteal flap; Type II: SPR avulsion with fibrocartilaginous ridge; Type III: Bony avulsion of fibula | Type I/II often managed with SPR repair; Type III may require bony fixation or groove deepening |
| Oden’s Classification | Focuses on fibular groove morphology: concave, flat, convex | Convex or flat grooves necessitate groove deepening procedures |
Diagnostic Pearls:
- Dynamic ultrasound during active ankle dorsiflexion and eversion is highly sensitive for detecting tendon subluxation.
- MRI provides detailed assessment of tendon tears, SPR integrityand groove morphology.
- Common pitfall: Misdiagnosis as lateral ankle sprain delays definitive treatment.
Decision-Making Algorithm
| Criteria | Non-Operative Management | Operative Management |
|---|---|---|
| Symptom Duration | Acute or intermittent symptoms <6 weeks | Chronic symptoms >6 weeks refractory to conservative care |
| Tendon Integrity | Intact tendons without tears | Tendon tears or degeneration present |
| SPR Status | Partial SPR injury without instability | Complete SPR rupture or persistent instability |
| Fibular Groove Morphology | Concave groove with stable tendons | Flat or convex groove requiring groove deepening |
| Functional Demand | Low-demand patients with minimal instability | High-demand athletes or patients with recurrent subluxation |
Rationale:
Non-operative treatment includes immobilization and physical therapy but has high failure rates in chronic cases. Surgical repair restores the SPR barrier and groove deepening addresses anatomical predisposition, reducing recurrence risk.
Surgical Mastery & Pearls
Step-by-Step Conceptual Overview:
- Patient Positioning and Exposure:
Position supine with a thigh tourniquet. Make a longitudinal incision posterior to the fibula over the peroneal tendons.
- Identification and Protection of Structures:
Carefully identify the peroneal tendons and sural nerve. Retract tendons anteriorly to expose the SPR and fibular groove.
- Assessment of Tendon and SPR:
Evaluate tendon integrity; debride degenerative tissue. Inspect SPR for tears or detachment.
- Groove Deepening:
Using a high-speed burr, create a concave fibular groove if flat or convex. Preserve cortical bone to maintain strength.
- SPR Repair or Reconstruction:
Reattach SPR to fibula with suture anchors or transosseous sutures. In cases of poor tissue quality, augment with local tissue or autograft.
- Tendon Stabilization Test:
Passively move the ankle through dorsiflexion and eversion to confirm tendon stability within the groove.
- Closure and Postoperative Immobilization:
Close in layers, immobilize in a short leg cast with the foot in slight eversion for 4-6 weeks.
Intraoperative Red Flags:
- Excessive tendon laxity after SPR repair suggests inadequate fixation or groove depth.
- Over-aggressive groove deepening risks fibular fracture or tendon attrition.
- Failure to protect the sural nerve can cause postoperative neuropathy.
Evidence-Based Synthesis
Recent literature confirms that isolated SPR repair without groove deepening yields higher recurrence rates, especially in patients with flat or convex fibular grooves. A randomized controlled trial comparing SPR repair alone versus combined repair and groove deepening demonstrated superior functional scores and lower recurrence in the combined group at two-year follow-up.
Ultrasound-guided dynamic assessment has emerged as a reliable diagnostic adjunct, improving preoperative planning. However, controversy persists regarding the optimal method of SPR reconstruction-direct repair versus augmentation-due to limited high-level evidence.
Biomechanical studies underscore the importance of restoring the fibro-osseous tunnel geometry to prevent tendon subluxation, reinforcing the surgical principle of groove deepening in anatomically predisposed patients.
Master Class Pro-Tip
During groove deepening, use intraoperative fluoroscopy to confirm preservation of the fibular cortex and avoid over-resection. Employ a tensioned suture anchor repair of the SPR with the ankle held in slight eversion and dorsiflexion to replicate physiological tendon tension. This nuanced step ensures optimal retinacular tensioning, minimizing postoperative laxity and recurrence, distinguishing the master surgeon’s technique from routine repair.
