Peroneal Tendon Repair and Reconstruction: An Intraoperative Masterclass

Introduction and Epidemiology

Pathology of the peroneal tendons represents a significant yet frequently underappreciated source of lateral ankle pain and dysfunction. These injuries may arise from a singular traumatic episode, such as a severe inversion ankle sprain, or manifest as an insidious consequence of chronic lateral ankle instability. In populations undergoing operative intervention for chronic ankle instability, intraoperative evaluation reveals that approximately 25% of patients harbor concomitant peroneal tendon tears. Despite this high prevalence in the unstable ankle, the true incidence of peroneal tendon pathology in the general population remains unknown due to widespread underdiagnosis.

Isolated tears of the peroneus brevis and peroneus longus are considered rare entities. However, delays in accurate diagnosis are alarmingly common, with contemporary literature indicating that up to 40% of peroneal tendon disorders are missed at the initial clinical evaluation. This diagnostic delay allows for progressive structural deterioration. When recognized early, direct primary repair of the peroneus brevis is highly feasible and consistently yields favorable functional outcomes. Conversely, neglected tears undergo progressive fibrocartilaginous metaplasia, retraction, and irreversible degeneration, often necessitating complex reconstructive procedures such as tenodesis, allograft interposition, or tendon transfer.

The natural history of peroneal tendon pathology is intimately linked to the mechanical environment of the retromalleolar groove. Tendons that frequently subluxate or frankly dislocate are subjected to abnormal shear forces, causing progressive fraying and longitudinal splitting at the distal tip of the fibula. Furthermore, chronic instability induces hypertrophy of the fibrocartilage lining the distal fibula, which exacerbates the mechanical impingement and accelerates the splitting of the peroneus brevis tendon.

Surgical Anatomy and Biomechanics

A profound comprehension of the lateral compartment anatomy and the intricate biomechanical interplay of the hindfoot is requisite for the successful surgical management of peroneal tendon disorders.

Musculotendinous Origins and Insertions

The peroneus brevis and peroneus longus muscles reside within the lateral compartment of the lower extremity and are innervated by the superficial peroneal nerve. The peroneus longus originates from the head and proximal two-thirds of the lateral fibula. Its tendon courses posterior to the lateral malleolus, traverses the cuboid tunnel, and inserts onto the plantar-lateral aspect of the base of the first metatarsal and the medial cuneiform. Biomechanically, the peroneus longus is a primary plantarflexor of the first ray and a secondary evertor of the foot. Its primary muscular antagonist is the tibialis anterior.

The peroneus brevis originates from the distal two-thirds of the lateral fibula. The muscle belly frequently extends distally, occasionally into the retromalleolar groove—a variant known as a low-lying muscle belly. The tendon inserts onto the tuberosity at the base of the fifth metatarsal. The peroneus brevis serves as the primary evertor of the foot and assists in ankle plantarflexion. Its primary muscular antagonist is the tibialis posterior.

Retinacular Structures and Fibular Groove

At the level of the lateral malleolus, the peroneus brevis tendon lies directly posterior to the fibular bone, while the peroneus longus tendon is situated posterior to the brevis. This orientation creates a mechanical vulnerability; during forceful dorsiflexion and eversion, the peroneus longus compresses the peroneus brevis against the fibula, generating a "nutcracker" effect that contributes to longitudinal split tears.

Both tendons are stabilized within the retromalleolar fibular groove by the superior peroneal retinaculum. This structure is a 1- to 2-cm wide fibrous sling extending from the posterolateral ridge of the distal fibula to the lateral wall of the calcaneus. The superior peroneal retinaculum is the primary restraint against peroneal tendon subluxation.

Distally, the inferior peroneal retinaculum provides further stabilization. It is continuous with the inferior extensor retinaculum anteriorly and passes obliquely to insert onto the lateral surface of the calcaneus. Within this region, the peroneal tubercle of the calcaneus acts as a bony fulcrum and physical separator for the two tendons. Injury to the inferior retinaculum rarely results in tendon subluxation but can contribute to localized tenosynovitis or stenosis.

Vascular Supply and Anatomic Variants

The vascular supply to the peroneal tendons is segmental. Injection studies have demonstrated distinct avascular zones within both tendons at the level of the lateral malleolus, precisely where they undergo the sharpest directional change. This reduced vascularity at the fibular turn significantly impairs intrinsic healing potential following microtrauma.

Anatomic variants frequently predispose patients to peroneal pathology. A shallow or convex retromalleolar groove reduces the containment volume for the tendons, predisposing them to subluxation. The presence of a peroneus quartus muscle—an accessory muscle found in up to 20% of the population—can cause overcrowding within the superior peroneal retinaculum, leading to stenosis and attritional wear. Similarly, a low-lying peroneus brevis muscle belly can functionally occlude the retromalleolar space, exacerbating mechanical impingement.

Indications and Contraindications

Surgical intervention is predicated on a thorough clinical evaluation, failure of appropriate non-operative modalities, and the presence of structural tendon damage or instability that correlates with the patient's symptomatology.

Pre Operative Planning and Patient Positioning

Thorough preoperative planning requires a meticulous physical examination and appropriate advanced imaging to clearly define the extent of the pathology and identify any concomitant biomechanical deformities that must be addressed concurrently.

Clinical Evaluation and Physical Examination

Patients typically present following a severe inversion ankle sprain or with a history of chronic lateral ankle instability. Acute or chronic swelling, accompanied by pain localized along the posterior border of the distal fibula, serves as a cardinal clinical indicator of peroneal pathology.

Palpation along the anatomic course of the tendons is critical. Pain localized precisely at the tip of the lateral malleolus is highly suggestive of a peroneus brevis tear. Conversely, pain localized more distally, near the base of the fifth metatarsal or at the cuboid tunnel, is more indicative of peroneus longus pathology.

Provocative testing should include active, resisted eversion and resisted ankle dorsiflexion. This maneuver frequently elicits sharp pain and may provoke palpable or visible subluxation of the tendons over the lateral malleolus. Eversion strength must be graded; significant weakness in the presence of pain suggests a high-grade tear or complete rupture.

Crucially, the overall alignment of the affected lower extremity must be assessed in a weight-bearing state. A cavovarus foot posture places excessive tension on the lateral ligamentous and musculotendinous structures. A fixed hindfoot varus deformity, often assessed via the Coleman block test, is a primary driver of peroneal tendon attrition. Failure to correct a fixed varus deformity at the time of tendon repair will inevitably lead to surgical failure and recurrent tearing.

Radiographic and Advanced Imaging

Standard weight-bearing radiographs of the foot and ankle (anteroposterior, lateral, and mortise views) are mandatory. While tendons are radiolucent, radiographs can reveal a "fleck sign"—a small cortical avulsion from the lateral ridge of the distal fibula pathognomonic for superior peroneal retinaculum avulsion. Radiographs also allow for the assessment of hindfoot alignment and the identification of a hypertrophic peroneal tubercle or an os peroneum.

Magnetic Resonance Imaging (MRI) without contrast is the gold standard for evaluating peroneal tendon pathology. Axial T2-weighted sequences are particularly useful for identifying fluid within the tendon sheath, tenosynovitis, and the classic "C-shape" or "boomerang" morphology of a peroneus brevis tendon undergoing longitudinal splitting. MRI also reliably identifies anatomic variants such as a peroneus quartus or a low-lying brevis muscle belly. Dynamic ultrasound is a valuable adjunct, offering real-time visualization of tendon subluxation and dynamic impingement, though it is highly operator-dependent.

Patient Positioning and Anesthesia

Surgery is typically performed under regional anesthesia (popliteal block) combined with general anesthesia or deep sedation. The patient is positioned in the lateral decubitus position to provide unhindered access to the posterolateral ankle. Alternatively, a supine position with a large bump placed under the ipsilateral hip can be utilized, allowing the leg to internally rotate. This position is particularly advantageous if concomitant procedures, such as a lateral ligament reconstruction (Broström-Gould) or a lateralizing calcaneal osteotomy, are planned. A well-padded thigh tourniquet is applied to maintain a bloodless surgical field.

Detailed Surgical Approach and Technique

The surgical management of peroneus brevis tears demands meticulous tissue handling, precise restoration of anatomy, and a structured algorithmic approach based on intraoperative findings.

Incision and Superficial Dissection

A longitudinal incision is made along the posterior border of the distal fibula, extending from approximately 3 to 4 cm proximal to the tip of the lateral malleolus down to the base of the fifth metatarsal. The incision should follow the natural curve of the tendons.

Careful subcutaneous dissection is paramount to avoid injury to the sural nerve and the lesser saphenous vein. The sural nerve typically crosses the surgical field posteroinferiorly; it must be identified, mobilized gently, and protected with a vessel loop throughout the procedure. The crural fascia is then incised to expose the peroneal tendon sheath.

Tendon Debridement and Tubularization

The superior peroneal retinaculum is identified and incised longitudinally. It is critical to leave a 2- to 3-mm cuff of retinacular tissue attached to the fibula to facilitate robust anatomical repair during closure. Once the retinaculum is reflected, the peroneal tendon sheath is opened, and tenosynovectomy is performed to allow for complete visualization of both tendons.

The peroneus brevis and longus are systematically inspected. The peroneus brevis is often found flattened and splayed around the peroneus longus. A longitudinal split tear is the most common pathological finding. The surgical decision-making process at this juncture is dictated by the percentage of viable tendon remaining.

If less than 50% of the cross-sectional area of the peroneus brevis is severely degenerated, the diseased, fibrillated central portion of the tendon is sharply excised. The remaining healthy tendon edges are then approximated and tubularized using a running locking suture of 4-0 non-absorbable or slowly absorbable material (e.g., Prolene or PDS). The knots are buried to minimize postoperative adhesions.

Tenodesis and Reconstruction Options

If greater than 50% of the peroneus brevis tendon is irreparably degenerated or absent, primary tubularization will result in a structurally incompetent unit. In these instances, a tenodesis is indicated. The diseased segment of the peroneus brevis is resected entirely. The proximal stump of the peroneus brevis is then sutured to the intact peroneus longus tendon under appropriate physiological tension (side-to-side tenodesis). The distal stump of the brevis is similarly tenodesed to the longus to maintain the eversion vector at the fifth metatarsal base.

In rare cases of massive, combined defects involving both the peroneus brevis and longus, more complex reconstructions are required. Options include the use of semitendinosus or gracilis allografts, or a flexor hallucis longus (FHL) tendon transfer to restore active eversion and plantarflexion.

Retromalleolar Groove Deepening

Following tendon repair, the depth of the retromalleolar groove must be assessed. If the groove is shallow or convex, or if tendon subluxation is reproducible intraoperatively, a groove deepening procedure is mandatory.

The most anatomically sound technique is the trapdoor procedure. A sharp osteotome is used to elevate a cortical flap of articular cartilage and bone from the posterior aspect of the lateral malleolus, leaving it hinged laterally. A high-speed burr is then utilized to excavate the underlying cancellous bone. The cortical trapdoor is then tamped back into the newly created concavity, effectively deepening the groove while preserving the smooth fibrocartilaginous gliding surface for the tendons.

Superior Peroneal Retinaculum Repair

The final, critical step is the meticulous repair of the superior peroneal retinaculum. The tendons are reduced into the deepened groove, and the ankle is taken through a full range of motion to ensure stability and absence of impingement. The retinaculum is then repaired to the fibular cuff using interrupted figure-of-eight sutures. If the retinaculum is redundant or attenuated, a "pants-over-vest" imbrication technique should be employed to securely tension the tissue.

If the fibular cuff is deficient, suture anchors may be placed directly into the posterolateral fibula to secure the retinaculum. Care must be taken not to overtighten the retinaculum, which could lead to postoperative stenosis and restricted tendon excursion.

Complications and Management

Surgical management of peroneal tendon tears carries inherent risks. Anticipation, early recognition, and aggressive management of complications are essential to preserve functional outcomes.

Post Operative Rehabilitation Protocols

A standardized, multiphasic rehabilitation protocol is crucial to balance the protection of the healing tendon repair with the prevention of debilitating peritendinous adhesions.

Phase I: Protection and Healing (Weeks 0-2)
Immediately postoperatively, the patient is placed in a bulky, non-weight-bearing short leg splint. The ankle is positioned in slight plantarflexion and eversion to minimize tension on the peroneal tendon repair and the superior peroneal retinaculum. Elevation and strict non-weight-bearing status are enforced to promote wound healing and reduce edema.

Phase II: Controlled Mobilization (Weeks 2-6)
At the two-week mark, sutures are removed. The patient is transitioned to a controlled ankle motion (CAM) boot. Weight-bearing status is gradually advanced from partial to full weight-bearing as tolerated. Active range of motion exercises in the sagittal plane (dorsiflexion and plantarflexion) are initiated to encourage tendon gliding and prevent adhesions. Inversion and eversion are strictly prohibited during this phase to protect the repair.

Phase III: Strengthening and Proprioception (Weeks 6-12)
The patient is transitioned out of the CAM boot into a supportive lace-up ankle brace. Physical therapy intensifies, focusing on progressive isometric, concentric, and eventually eccentric strengthening of the peroneal musculature. Proprioceptive training using balance boards and foam pads is initiated to restore neuromuscular control of the lateral ankle complex.

Phase IV: Return to Sport (Weeks 12+)
Sport-specific dynamic training, plyometrics, and agility drills are introduced. Return to high-impact activities or competitive sports is typically permitted between 3 and 5 months postoperatively, contingent upon the restoration of symmetric eversion strength, pain-free full range of motion, and successful completion of functional testing.

Summary of Key Literature and Guidelines

The academic foundation for the treatment of peroneal tendon tears is built upon several landmark studies and classification systems. Krause and Brodsky fundamentally categorized peroneus brevis tears, establishing the >50% cross-sectional area rule that continues to dictate the choice between primary tubularization and tenodesis. Their long-term outcome studies demonstrated excellent functional results when this algorithm is strictly applied.

Furthermore, the Eckert and Davis classification of superior peroneal retinaculum injuries remains the standard for understanding the varied pathology of retinacular avulsions and their contribution to tendon subluxation. Modern literature heavily emphasizes the necessity of addressing the osseous architecture. Studies by Title et al. and others have definitively shown that failure to correct a cavovarus foot deformity dramatically increases the failure rate of isolated peroneal tendon repairs.

Current orthopedic consensus guidelines strongly advocate for early MRI evaluation in patients with chronic lateral ankle pain and instability to minimize the 40% missed diagnosis rate. When surgical intervention is undertaken, a comprehensive approach that includes tendon debridement, anatomical repair, groove deepening when indicated, and meticulous retinacular reconstruction provides the most reliable pathway to full functional recovery and return to pre-injury activity levels.

Clinical & Radiographic Imaging