What is the treatment for a longitudinal split tear of the peroneus brevis?

Treatment of Longitudinal Split Tear of Peroneus Brevis

Surgical repair is the standard of care for longitudinal split tears of the peroneus brevis tendon, as conservative treatment rarely provides adequate relief for this mechanical tendon injury. 1, 2

Initial Conservative Management (Limited Role)

While conservative measures are almost always attempted initially, they have limited success for true longitudinal splits 1:

• Immobilization with below-knee cast or walking boot for 4-6 weeks may be trialed in acute presentations 3
• Transition to ankle bracing with supportive therapy and analgesics after immobilization 4
• Structured rehabilitation program including proprioceptive training, coordination exercises, and functional activities if conservative approach is pursued 5

Important caveat: Conservative treatment frequently fails because longitudinal splits represent a mechanical structural abnormality rather than simple tendinopathy, making surgical intervention necessary in most symptomatic cases 1, 2

Surgical Treatment (Standard of Care)

Surgical Approach Selection

The extent of tendon damage determines the surgical technique 1, 2:

For less extensive tears (<50% tendon involvement):

• Débridement and tubularization (side-to-side suturation of the split tendon) 1, 2
• This involves repairing the longitudinal split with direct suturing to restore tendon continuity 3

For more severe tears (>50% tendon involvement or extensive damage):

• Resection of damaged tendon segments with tenodesis of proximal and distal segments to the peroneus longus 1, 2
• This sacrifices the irreparable portion while maintaining some peroneal function 6

Addressing Contributing Factors

Critical surgical principle: Always identify and treat underlying causes during the same procedure 6:

• Repair chronic peroneal tendon subluxation or dislocation if present (common contributing factor) 6
• Correct lateral ankle instability with ligament reconstruction if mechanical instability exists 6
• Address hindfoot varus deformity with calcaneal osteotomy if present, as this predisposes to recurrent injury 6
• Smooth any sharp posterior fibular ridge that may cause mechanical irritation 1

Postoperative Protocol

Standard immobilization: 3, 6

• 4 weeks in below-knee cast with non-weightbearing or protected weightbearing
• Followed by progressive mobilization and transition to ankle brace
• Structured rehabilitation focusing on proprioception, strength, and coordination 5
• Gradual return to activities based on functional recovery rather than arbitrary timeframes 5

Diagnostic Considerations

MRI is the most accurate imaging modality for diagnosing peroneus brevis splits preoperatively 3

Ultrasound offers dynamic assessment with 100% positive predictive value for tendon subluxation when compared to surgical findings 5

Common pitfall: These injuries are frequently misdiagnosed as simple lateral ankle sprains, leading to delayed treatment and worse outcomes 3, 1. Suspect peroneus brevis pathology in patients with:

• Persistent lateral ankle pain after "ankle sprain" 3
• Swelling along the peroneal tendon sheath 1, 4
• Pain with resisted eversion 1
• History of recurrent ankle sprains or chronic inflammatory disease 3

Expected Outcomes

With appropriate surgical treatment: 1, 6

• Good to excellent results in 91% of patients achieving normal or moderate peroneal muscle strength 6
• Mean postoperative AOFAS ankle scores of 82 points 6
• Return to maximum activity is prolonged (typically several months) but functional outcomes are favorable with proper patient selection 1

Warning: Inadequate treatment of contributing factors (instability, subluxation, varus deformity) leads to poor outcomes and potential rerupture 3, 6