What is the management for a patient with an avulsion fracture (avulsion fx) of the lateral malleolus, as evidenced by x-ray, who is weight-bearing?

Management of Avulsion Fracture of the Lateral Malleolus in a Weight-Bearing Patient

Treat this patient with functional treatment using a lace-up ankle brace, allow protected weight-bearing as tolerated, and initiate immediate exercise therapy—this approach is superior to immobilization for avulsion fractures of the lateral malleolus. 1

Initial Assessment and Fracture Characterization

• Confirm the diagnosis with standard three-view ankle radiographs (anteroposterior, lateral, and mortise views) to assess fragment size, displacement, and ankle mortise alignment 1
• If the avulsion fragment is not clearly visible on standard views, obtain an anterior talofibular ligament (ATFL) view radiograph, as up to 50 patients in one series showed negative standard radiographs but positive ATFL views 2
• Assess for ankle mortise instability by measuring the medial clear space on mortise radiographs—widening >4mm indicates deltoid ligament disruption and requires surgical intervention 3
• Examine for associated injuries including syndesmotic disruption, deltoid ligament injury, and peroneal tendon subluxation (which presents with tenderness at the peroneal groove and anterior subluxation of tendons) 4

Treatment Protocol for Stable Avulsion Fractures

Apply a lace-up ankle brace immediately as it provides superior outcomes compared to elastic bandages or tape, with better reduction of swelling, fewer complications, and faster return to work 1

Weight-Bearing and Mobilization

• Allow protected weight-bearing as tolerated from the outset—functional supports permit controlled loading of damaged tissues, which is superior to complete immobilization 5
• Continue brace use for the full 4-6 week period to ensure adequate healing while maintaining mobility 5
• Avoid prolonged immobilization as it results in worse outcomes, slower return to work, and increased risk of chronic instability 5, 1

Exercise Therapy (Start Immediately)

• Initiate neuromuscular and proprioceptive exercises immediately, as this reduces recurrent injury risk and prevents functional ankle instability 5
• Add manual joint mobilization combined with exercise therapy for better outcomes—this improves dorsiflexion range of motion and decreases pain more effectively than exercise alone 5
• Prescribe a home exercise program for patient independence and continued rehabilitation 5

When Surgical Intervention Is Required

Surgery is indicated if:

• Medial clear space measures >4mm on mortise radiographs, indicating bimalleolar equivalent injury with deltoid ligament disruption 3
• The avulsion fragment is large enough to compromise ankle mortise stability or involves significant articular surface 3
• There is evidence of peroneal tendon subluxation with retinaculum avulsion (pathognomonic finding: avulsion fracture from lateral cortex of lateral malleolus) 4

Note that research shows outcomes of avulsion fractures treated functionally are inferior to pure ligament injuries, but still achieve good results with appropriate management 2

Follow-Up and Monitoring

• Re-examine at 4-5 days post-injury when the anterior drawer test has optimized sensitivity and specificity 5
• Look for four findings indicating complete lateral ligament rupture: hematoma, pain on palpation, positive anterior drawer test, and significant swelling 5
• If pain persists beyond 1-3 weeks despite appropriate treatment, order MRI without contrast to evaluate for occult fractures, osteochondral lesions, bone marrow edema, peroneal tendon injury, or syndesmosis injury 5
• Obtain weight-bearing radiographs at follow-up to assess dynamic stability and ensure proper healing 1

Expected Recovery Timeline

• Return to light work: 2-3 weeks for most avulsion fractures 5
• Full return to former work: 3-6 weeks depending on physiotherapy response 5
• Therapeutic response should be evident within 2 weeks of functional treatment 5

Critical Pitfalls to Avoid

• Do not miss associated deltoid ligament injury—5-8mm medial clear space widening on stress testing may still have intact or partially torn deep deltoid on MRI, but complete rupture requires surgery 6
• Avoid using ultrasound, laser therapy, electrotherapy, or short-wave therapy as they have no proven benefit 5
• Do not use elastic bandages or tubigrip as sole treatment—they are inferior to proper ankle braces 5
• Recognize that 5-33% of patients still have pain and instability complaints after 1 year, and 3-34% experience recurrent ankle sprains, emphasizing the importance of proper exercise therapy 1
• Failure to recognize peroneal retinaculum injury can lead to chronic subluxation requiring operative reconstruction 4