Bimalleolar Ankle Fracture

Definition

  • Fracture of both the medial and lateral malleoli, disrupting both sides of the ankle ring
  • Bimalleolar equivalent is a lateral malleolar fracture with deltoid ligament rupture

Aetiology

  • Rotational injury, most often supination external rotation (Lauge-Hansen SER IV)
  • Pronation external rotation and pronation abduction patterns also produce bimalleolar injuries

Classification

Weber

Based on fibular fracture level relative to the syndesmosis

TypeFibular fracture level
ABelow the syndesmosis
BAt the syndesmosis
CAbove the syndesmosis

Lauge-Hansen

  • Foot position then deforming force, giving SER, SA, PER and PA patterns
  • Predicts the sequence of ligament and bone failure

Clinical Features

  • Pain, swelling and bruising on both sides of the ankle
  • Check skin for tenting or blistering and assess neurovascular status

Investigations

Ankle Fractures, radiograph of a bimalleolar ankle fracture
Radiograph of a bimalleolar ankle fracture. Image by Article authors: Nazzar Tellisi, I S Abdulkareem, P G Giannoudis, Wikimedia Commons, CC BY 4.0.
  • AP, lateral and mortise radiographs of the ankle
  • Medial clear space widening over 4 mm suggests deltoid incompetence
  • Full length tibia films if a proximal fibular fracture (Maisonneuve) is suspected
  • CT if a posterior malleolar fragment is seen or suspected

Management

  • Urgent closed reduction and backslab for any talar shift or skin compromise
  • Unstable injury, so ORIF is standard in fit patients
  • Lateral malleolus fixed with lag screw and neutralisation plate, or posterior antiglide plate
  • Medial malleolus fixed with two partially threaded cancellous screws or tension band wiring
  • Syndesmosis stressed intraoperatively after bony fixation
  • AIM trial showed close contact casting matched ORIF function at 6 months in patients over 60
  • Delay surgery until swelling settles if skin wrinkles are absent

Complications

  • Wound breakdown and infection, higher in diabetes, smokers and the elderly
  • Malunion with fibular shortening or rotation leads to talar shift
  • Post-traumatic arthritis
  • Symptomatic hardware
  • DVT

Prognosis

  • Accurate restoration of the mortise gives good results in most patients
  • Talar shift of 1 mm reduces tibiotalar contact area by about 40% (Ramsey and Hamilton)

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