What are the treatment guidelines for a patient with a non-displaced or minimally displaced avulsion fracture of the distal fibula?

Treatment Guidelines for Avulsion Fracture of Distal Fibula

For non-displaced or minimally displaced avulsion fractures of the distal fibula, initial management consists of posterior splinting from below the knee to the toes with the ankle in neutral position for approximately 3 weeks, combined with immediate active toe motion exercises. 1

Initial Assessment and Stability Determination

Before initiating treatment, you must evaluate for associated injuries that would change management:

• Check for medial ankle tenderness, bruising, or swelling – these findings suggest deltoid ligament injury and potential instability requiring surgical consideration rather than conservative management 1
• Assess the medial clear space on weight-bearing radiographs – if less than 4mm, the fracture is stable and appropriate for conservative treatment 1
• Examine the fracture location relative to the syndesmosis – fibular fractures above the syndesmosis carry higher risk of syndesmotic injury 1
• Evaluate for peroneal tendon pathology – avulsion fractures of the distal fibula tip are pathognomonic of superior peroneal retinaculum rupture with or without peroneal tendon displacement 2

Conservative Management Protocol

For stable, isolated, minimally displaced avulsion fractures:

• Apply a posterior splint extending from below the knee to the toes with the ankle at 90 degrees to prevent equinus contracture and accommodate anticipated swelling in the first 48-72 hours 1
• Initiate immediate active toe motion exercises to prevent stiffness, which is one of the most functionally disabling complications 1
• Maintain immobilization for approximately 3 weeks with radiographic follow-up to confirm adequate healing 1
• Obtain weight-bearing radiographs at follow-up to provide critical information about fracture stability, particularly the medial clear space 1

When Surgical Intervention is Indicated

Conservative management is inappropriate in several scenarios:

• Symptomatic nonunion with chronic ankle instability – surgical fixation or ligament reconstruction is required, as nonunion results in dysfunction of the anterior talofibular ligament 3, 4
• Displaced fractures with ankle instability – concomitant ankle instability should be addressed surgically when present 3
• Bi- or trimalleolar fractures – these are inherently unstable and typically require surgical fixation 1
• Open fractures or high-energy mechanisms – warrant immediate orthopedic consultation 1

Surgical outcomes for symptomatic os subfibulare (posttraumatic avulsion fragment) generally result in substantial improvement with relatively low complication rates 3. In the elderly population with displaced fractures, minimally invasive intramedullary nailing has emerged as an alternative to traditional open reduction and internal fixation 5.

Critical Pitfalls to Avoid

• Do not miss associated peroneal tendon pathology – recognition and proper management by immobilization or surgery prevents future tendon dysfunction 2
• Do not overlook Maisonneuve fracture patterns – always examine the proximal fibula 1
• Monitor for immobilization complications including skin irritation and muscle atrophy, which occur in approximately 14.7% of cases 1
• In pediatric patients, recognize that chronic ankle instability may result from avulsion fracture nonunion rather than typical ligamentous injury, requiring different surgical approaches 4