Peroneal tendonitis

Peroneal tendonitis is a condition characterized by inflammation of the peroneal tendons located on the outer side of the ankle. It commonly affects athletes and individuals involved in repetitive ankle movements. Early recognition and management are crucial to prevent chronic degeneration and functional impairment.

Anatomy of the Peroneal Tendons

Peroneus Longus

The peroneus longus tendon originates from the lateral aspect of the fibula and travels posterior to the lateral malleolus. It passes under the foot to insert on the medial cuneiform and the base of the first metatarsal. This tendon is responsible for eversion and plantarflexion of the foot, contributing to lateral stability of the ankle.

Peroneus Brevis

The peroneus brevis tendon lies beneath the peroneus longus and originates from the lower two-thirds of the lateral fibula. It passes behind the lateral malleolus and inserts onto the base of the fifth metatarsal. Its primary functions are foot eversion and stabilization during gait, particularly on uneven surfaces.

Retinacula and Supporting Structures

The superior and inferior peroneal retinacula are fibrous bands that hold the peroneal tendons in place behind the lateral malleolus. These structures prevent tendon subluxation during ankle movement. Additionally, the tendons are surrounded by synovial sheaths that facilitate smooth gliding and reduce friction.

Blood Supply and Innervation

The peroneal tendons receive blood supply from branches of the peroneal artery and small vessels from surrounding tissues. Innervation is provided primarily by the superficial peroneal nerve, which also contributes to sensation along the lateral foot and ankle. Adequate vascularization is important for tendon healing and repair.

Pathophysiology

Mechanism of Injury

Peroneal tendonitis typically results from overuse or repetitive stress, leading to microtrauma of the tendons. Acute injuries can occur during forced inversion or eversion movements, while chronic overloading from activities such as running or jumping gradually damages tendon fibers.

Inflammatory Process

Repeated microtrauma initiates an inflammatory response within the tendon sheath, leading to swelling, pain, and reduced tendon gliding. Cellular infiltration and increased vascular permeability contribute to the symptomatic presentation of tendonitis.

Chronic Degeneration vs Acute Tendinitis

Acute tendonitis involves active inflammation and is usually reversible with conservative management. Chronic degeneration, also known as tendinosis, is characterized by tendon fiber disorganization, thickening, and reduced elasticity. This stage may occur without significant inflammation and requires targeted rehabilitation to restore tendon function.

Risk Factors

Intrinsic Factors

• Foot Anatomy: Structural variations such as pes cavus, hindfoot varus, or high arches increase lateral ankle stress and predispose to peroneal tendon overload.
• Muscle Imbalances: Weakness or imbalance in the peroneal muscles compared to the tibialis anterior and calf muscles can alter biomechanics and increase tendon strain.
• Previous Ankle Injuries: History of ankle sprains or fractures can lead to chronic instability, increasing the risk of tendonitis.

Extrinsic Factors

• Overuse: Repetitive activities such as running, soccer, basketball, and dancing place repeated stress on the peroneal tendons.
• Improper Footwear: Shoes that do not provide adequate lateral support or cushioning may increase tendon loading.
• Surface and Training Errors: Training on uneven or hard surfaces, sudden increases in intensity or volume, and poor technique can all contribute to tendon injury.

Clinical Presentation

Symptoms

• Lateral Ankle Pain: Pain localized behind the lateral malleolus or along the course of the peroneal tendons, often exacerbated by activity.
• Swelling and Tenderness: Mild to moderate swelling may be present, with tenderness on palpation over the tendon sheath.
• Snapping or Instability: Some patients may experience a snapping sensation during ankle movement or feelings of lateral ankle instability.

Physical Examination Findings

• Palpation: Tenderness along the peroneus longus and brevis tendons, sometimes with thickening.
• Range of Motion: Pain may increase with resisted eversion or plantarflexion of the foot.
• Special Tests: Clinical maneuvers, such as the peroneal tendon subluxation test, may reproduce symptoms or reveal tendon displacement behind the lateral malleolus.

Diagnostic Evaluation

Imaging Studies

• X-ray: Primarily used to rule out bony abnormalities, fractures, or osteochondral lesions; does not directly visualize tendons.
• Ultrasound: Useful for dynamic assessment of tendon structure, detecting tears, subluxation, and inflammation within the tendon sheath.
• MRI: Provides detailed evaluation of tendon integrity, surrounding soft tissue, and chronic degenerative changes; considered the gold standard for complex cases.

Differential Diagnosis

• Lateral Ankle Sprain: Ligament injury presenting with similar lateral ankle pain but usually with acute trauma and joint instability.
• Fibular Stress Fractures: Stress reactions of the distal fibula can mimic tendon pain and may require imaging for confirmation.
• Osteochondral Lesions: Cartilage or subchondral bone damage in the talus can produce lateral ankle discomfort.
• Other Tendon Pathologies: Involvement of the Achilles or posterior tibial tendons should be considered in atypical presentations.

Treatment Options

Conservative Management

• Rest and Activity Modification: Reducing or avoiding activities that exacerbate symptoms allows the tendon to heal.
• Physical Therapy: Stretching, strengthening, and proprioception exercises to restore tendon function and ankle stability.
• Immobilization and Bracing: Short-term use of ankle supports, walking boots, or braces to limit stress on the tendon.
• Anti-inflammatory Medications: NSAIDs may be prescribed to reduce pain and inflammation in the acute phase.

Interventional Treatments

• Corticosteroid Injections: Rarely used due to risk of tendon weakening; may be considered in refractory cases under imaging guidance.
• Platelet-Rich Plasma Therapy: Emerging treatment aimed at promoting tendon healing and regeneration in chronic tendonitis.

Surgical Management

• Tendon Repair or Debridement: Indicated for partial tears, persistent pain, or chronic degeneration unresponsive to conservative therapy. Damaged tendon tissue is cleaned or sutured to restore function.
• Tendon Reconstruction or Grafting: Required in cases of complete rupture or severe degeneration. Autografts or allografts may be used to reconstruct the tendon and restore stability.
• Postoperative Rehabilitation: Gradual mobilization, strengthening, and proprioception exercises are essential to restore normal ankle mechanics and prevent recurrence.

Prevention Strategies

• Proper Footwear Selection: Shoes with adequate lateral support and cushioning help reduce tendon stress during activities.
• Strengthening and Flexibility Exercises: Regular peroneal muscle strengthening and stretching programs maintain tendon resilience and ankle stability.
• Gradual Training Progression: Incremental increases in activity intensity, frequency, and duration minimize overuse injuries.
• Biomechanical Correction: Orthotics or corrective devices may be used for foot deformities or gait abnormalities that predispose to tendon overload.

Prognosis

The prognosis of peroneal tendonitis is generally favorable with early diagnosis and appropriate management. Patients who adhere to conservative treatment protocols, including rest, physical therapy, and activity modification, often experience symptom resolution within several weeks to months. Chronic or severe cases requiring surgical intervention may have a longer recovery period, but most patients regain full ankle function with proper rehabilitation.

Recurrence is possible, particularly if underlying risk factors such as abnormal foot biomechanics, inadequate footwear, or premature return to high-impact activities are not addressed. Long-term outcomes are improved through targeted strengthening, flexibility exercises, and ongoing preventive measures to maintain tendon health.

References

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