Trimalleolar Ankle Fracture

Definition

  • Fracture of the medial, lateral and posterior malleoli
  • Posterior malleolus is the posterior lip of the distal tibial plafond

Aetiology

  • Rotational injury, most often SER IV or PER IV Lauge-Hansen patterns
  • Posterior fragment avulsed by the posterior inferior tibiofibular ligament (PITFL)

Anatomy

  • PITFL attaches to the posterior malleolus, so the fragment carries syndesmotic stability
  • Posterolateral fragment is also called the Volkmann fragment

Classification

Haraguchi (CT based)

TypeDescription
1Posterolateral oblique
2Medial extension
3Small shell fragment

Original publication Haraguchi N, Haruyama H, Toga H, Kato F. Pathoanatomy of posterior malleolar fractures of the ankle. J Bone Joint Surg Am. 2006;88(5):1085-92.

Bartonicek

  • Five types based on fragment shape, fibular notch involvement and tibial stability

Clinical Features

  • Marked swelling and possible posterior talar subluxation or dislocation
  • Fracture dislocations need urgent reduction to protect skin

Investigations

Open Reduction Internal Fixation, trimalleolar ankle fracture before and after open reduction and internal fixation
Trimalleolar ankle fracture before and after open reduction and internal fixation. Image by Chaim Mintz, Wikimedia Commons, CC BY-SA 4.0.
  • AP, lateral and mortise radiographs
  • Lateral view underestimates fragment size
  • CT recommended to define fragment morphology and plan approach

Management

  • Closed reduction and backslab, then ORIF when soft tissues allow
  • External fixator for unstable dislocation or poor skin
  • Posterior fragment fixation indicated for talar subluxation or articular step over 2 mm
  • The older 25 to 33% fragment size rule is less favoured now
  • Fixing the posterior malleolus restores PITFL tension and may avoid a syndesmotic screw
  • Posterolateral approach between peroneals and FHL allows fibula and posterior malleolus fixation
  • Posteromedial approach for fragments with medial extension
  • Anterior to posterior lag screws are an option for undisplaced fragments

Complications

  • Post-traumatic arthritis, more frequent than in bimalleolar fractures
  • Wound breakdown and infection
  • Malreduction of the posterior fragment and syndesmosis
  • Sural nerve injury with the posterolateral approach

Prognosis

  • Worse functional outcomes than bimalleolar fractures
  • Anatomic reduction of the articular surface and syndesmosis gives the best results

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.