What is the treatment for an unstable ankle due to a posterior malleolar fracture?

Treatment of Unstable Ankle Due to Posterior Malleolar Fracture

Direct surgical repair of the posterior malleolus through a posterolateral or posteromedial approach (based on fracture pattern) is the recommended treatment for unstable ankle fractures involving the posterior malleolus, as this provides the highest rate of anatomic reduction, stability, and healing. 1

Diagnostic Approach

• CT imaging is essential for proper evaluation of posterior malleolar fractures
  • Multidetector CT is particularly useful for complex injuries such as posterior malleolar fractures and posterior pilon variant fractures 2
  • CT provides superior detection of occult fractures compared to radiographs (87% vs 78% sensitivity) 2
  • Fracture pattern classification based on CT findings guides surgical approach selection 3

Fracture Classification and Surgical Approach Selection

Based on CT findings, posterior malleolar fractures can be classified using either:

1. Haraguchi Classification:

   • Type I (posterolateral-oblique): Use posterolateral approach
   • Type II (medial-extension): Use posteromedial approach
   • Type III (small-shell): Use posterolateral approach

2. Bartoníček Classification:

   • Types 1,2,4: Use posterolateral approach
   • Type 3: Use posteromedial approach

Surgical Management

Posterolateral Approach

• Indicated for Haraguchi I/III and Bartoníček 1/2/4 fractures
• Patient positioned prone
• Allows direct visualization and fixation of posterolateral fragments
• Fibula fracture can be addressed through the same approach or through a subcutaneous window 3

Posteromedial Approach

• Indicated for Haraguchi II and Bartoníček 3 fractures
• Can be performed with patient supine
• Allows direct visualization of articular reduction
• Usually combined with a lateral approach for fibular fixation 3, 4

Fixation Technique

• Direct fixation of posterior malleolus with buttress plate and/or lag screws
• Anatomic reduction of the articular surface is critical
• Direct posterior malleolus repair may eliminate the need for transsyndesmotic fixation (only 1.3% of patients required transsyndesmotic fixation following posterior malleolus repair) 1

Expected Outcomes and Complications

• High healing rate (100% in a recent study) with mean healing time of 2.9 months 1
• Excellent anatomic reduction rates (98.8%) 1
• Potential complications:
  • Superficial wound complications (11.3%) - more common with ankle fracture dislocations 1
  • Sural nerve dysesthesia (3.8%) 1
  • Loss of reduction (1.3%) 1

Rehabilitation Protocol

• Early mobilization is recommended to prevent stiffness and improve functional outcomes 2
• Progressive weight-bearing based on stability of fixation and healing
• Monitor for complications such as chronic pain, post-traumatic arthritis, malunion, and infection 2

Clinical Pearls

• The size of the posterior malleolar fragment alone should not determine management; other factors like displacement, articular congruency, and tibiotalar subluxation are more important 5
• Direct posterior malleolus fixation provides better stability than indirect reduction techniques
• Anatomic reduction of both the articular surface and fibular notch is essential for ankle stability and functional outcomes 3
• CT imaging is crucial for proper pre-operative planning and surgical approach selection