Management of Avulsion Injury of Medial Malleolus
For isolated avulsion fractures of the medial malleolus tip, conservative management with immobilization and radiographic follow-up is the primary treatment, but surgical fixation is required for large fragments (>15mm) or when the medial clear space exceeds 4mm, indicating ankle instability. 1
Initial Diagnostic Evaluation
Radiographic Assessment
- Obtain standard three-view ankle radiographs (anteroposterior, lateral, and mortise views) to evaluate the fracture fragment size, displacement, and overall ankle alignment 1
- Apply Ottawa Ankle Rules to determine imaging necessity in acute ankle trauma 1
- Measure the medial clear space on mortise views—a measurement >4mm confirms instability and mandates surgical intervention 1, 2
- Consider CT scanning for complex cases to determine exact fragment extent, displacement, and intra-articular extension 1
- Obtain weight-bearing radiographs during follow-up to assess dynamic stability, as these provide critical information about ankle mortise integrity 1, 2
Critical Assessment Points
- Evaluate for associated ligamentous injuries, particularly deltoid ligament disruption, which commonly accompanies medial malleolar avulsion fractures 1, 3
- Search for concomitant anterolateral tibial plafond fractures when oblique medial malleolar fractures are identified, as these injuries occur together through external rotation, dorsiflexion, and abduction mechanisms 4
- Assess for posterior tibial tendon dislocation, which can occur with medial malleolar avulsion fractures 5
Treatment Algorithm
Conservative Management (Primary Approach for Small Fragments)
- Immobilize isolated avulsion fractures of the medial malleolus tip with fragments <15mm that maintain ankle stability 1
- Perform regular radiographic follow-up to confirm healing progression 1
- Ensure medial clear space remains <4mm on serial radiographs to confirm maintained stability 1
Surgical Management Indications
- Large fragments >15mm that may affect joint stability require surgical intervention 1
- Any displacement >2mm in the setting of bimalleolar fractures mandates surgical management due to inherent instability 2
- Medial clear space >4mm on mortise radiographs is an absolute indication for open reduction and internal fixation (ORIF) 1, 2
- Arthroscopically assisted reduction and fixation can restore medial ankle stability while allowing direct visualization of the ankle mortise and deltoid ligament integrity 3
- For traumatic posterior tibial tendon dislocation with medial malleolar avulsion, surgical repair using periosteal flap and suture anchor fixation provides stable tendon gliding 5
Surgical Timing
- Perform ORIF as soon as medically feasible, ideally within 24-48 hours if soft tissue conditions permit 2
- Delays beyond one week increase risks of soft tissue complications, surgical difficulty, and malunion 2
Post-Treatment Management
Follow-Up Protocol
- Obtain serial radiographs at 2,6, and 12 weeks to confirm maintenance of reduction and fracture healing 2
- Use weight-bearing radiographs to assess stability, confirming medial clear space <4mm 1
- Implement early mobilization with functional treatment after adequate initial healing, as this improves outcomes compared to prolonged immobilization 2
Critical Pitfalls to Avoid
- Failure to recognize associated ligamentous injuries (particularly deltoid ligament disruption) compromises outcomes and may lead to chronic instability 1, 2
- Inadequate radiographic evaluation may miss subtle fracture patterns, associated anterolateral tibial plafond fractures, or syndesmotic injuries 1, 4
- Overly aggressive rehabilitation before adequate healing can lead to fragment displacement or nonunion 1
- Underestimating the significance of medial clear space widening leads to missed instability and poor long-term outcomes 1, 2
- Failing to obtain weight-bearing radiographs in equivocal cases misses dynamic instability that requires surgical intervention 1, 2