• The ankle mortise is the articulation between the talus and the distal tibia/fibula.
• The distal tibia has 3 important parts: The medial malleolus prevents excessive inversion, the plafond (inferior roof), and the posterior malleolus contributes to joint congruency.
• The distal fibula forms the lateral malleolus, which prevents excessive eversion.
• Three ligamentous groups hold the mortise together: deltoid ligament (medial), syndesmosis (tibiofibular) and three lateral ligaments (anterior talofibular, calcaneofibular, posterior talofibular).
• Stability of the mortise is the primary determinant in fracture management.

Common Mechanisms of Injury

• Inversion injuries can disrupt the lateral ligaments, cause avulsion to the lateral malleolus or with increasing force impact the talus into the medial malleolus, causing medial malleolar fracture.
• Eversion injuries can transmit force up the fibula, causing a syndesmotic injury and/or higher fibular fracture.
• High energy significant axial loading can lead to pilon fracture (complicated fracture of the distal tibia).

History and Physical

• Palpate all ligaments thoroughly as any disruption threatens the joint stability.
• High (proximal) fibular tenderness may indicate a Maisonneuve fracture.
• Tenderness when squeezing the distal tibia/fibula together may indicate syndesmotic injury.
• Ensure the ankle is not dislocated, as fracture-dislocations need to be emergently reduced¹.
• Confirm distal neurovascular status, including both posterior tibialis and dorsalis pedis pulses.
• Ensure no open fracture or skin tenting.

Imaging

• Ottawa Ankle Rule indications to image.
• Inspect the mortise view for uniformity or shift = an unstable ankle.
• Medial ankle injury or proximal fibular tenderness requires imaging of the full fibula to rule out a Maisonneuve fracture¹.
• Displaced or oblique malleolar fracture are usually associated with impact from the talus and should raise concern for ligamentous damage on the opposite side of the ankle.
• Pilon fractures are associated with high energy mechanisms and warrant further examination for other injuries including foot.

Stability

• In general, isolated malleolar fractures are stable if non-displaced and not associated with ligamentous injury.
• Disruption of >1 structure supporting the ankle mortise (boney or ligamentous) generally confers instability¹.
• The Weber classification is useful:
  • Type A fractures occur below the level of the tibiotalar joint line and spare the syndesmosis. They are generally stable.
  • Type B fractures occur at the level of the tibiotalar joint and may involve the syndesmosis, thus have variable stability. The presence of concomitant medial ankle damage makes syndesmotic involvement more likely.
  • Type C fractures occur above the tibiotalar joint and very often involve syndesmotic injury, making them unstable.
• Ankle injury involving syndesmotic damage may lead to a proximal fibular fracture, (Maisonneuve fracture) = unstable.
• Medial ankle injury should raise concern for concomitant deltoid ligament injury via an eversion mechanism = unstable.
• Posterior malleolar fractures are often not isolated² and should raise suspicion for concomitant ankle damage.

Orthopedic Referral

• Acute: open fractures/skin tenting, neurovascular compromise, fracture dislocations (following immediate reduction), any gross instability or deformity.
• Urgent outpatient referral:
  • unstable injuries, displacement, loss of joint congruency.
  • Consider for all medial malleolar fractures to ensure joint and syndesmotic stability¹.
  • Consider for any posterior malleolar fractures involving >25% of the articular surface². Timing is often within 24-48 hours, although practice variation may exist.
  • Consider consult for all other ankle fractures within 1 week.

Acute Intervention

• Ice and elevation above the knee over the first 48 hours. Address pain.
• Reduce any acute dislocation or displacement. Pre-reduction x-rays are helpful but should not impede reduction when neurovascular status is compromised.
• If acute orthopedic consultation is required, keep immobilized and non-weight bearing.

Immobilization

• All immobilizations should be done at 90^o to avoid Achilles shortening.
• Fractures requiring acute or urgent orthopedic consult should be immobilized while awaiting assessment. Posterior or sugar tong splints are commonly used.
• Short leg cast or walking boots are commonly used for definitive management of stable fractures.
• Always confirm neurovascular status after immobilization.
• Strict non-weightbearing is required if unstable. Stable injuries may weight bear as tolerated. If in doubt consult orthopedics.

Definitive Non-Operative Management for Stable Uncomplicated Injuries

• Most ankle fractures should receive orthopedic follow-up as there is a lack of evidence delineating the benefit of surgical -vs- conservative management of many fracture patterns³_.
• Some stable and uncomplicated fractures may be managed by primary care physicians, depending on regional practice and referral patterns.
• Small, isolated avulsion tip fractures of the lateral or medial malleoli may be considered on the spectrum of ankle sprain and treated as such¹.
• Truly isolated, non-displaced malleolar fractures not associated with ligamentous damage may be immobilized until clinically healed (4-6 weeks on average).

Disposition

• Discuss red flags indicative of neurovascular compromise that should prompt return to the ED.
• Consider ortho follow up for all ankle fractures.
• Follow up with primary care physician at 1-2 weeks to ensure integrity of immobilization and patient compliance. Repeat imaging should be completed to confirm adequate alignment.

Complications

• Uncommon in isolated, stable injuries.
• Precise alignment of the ankle is required to retain normal biomechanics and avoid subsequent degenerative changes. Instability, displacement, comminution, and articular involvement are risk factors for poor function and require orthopedic referral.

1. Walls RM, Hockberger RS, Gausche-Hill M, Erickson TB, Wilcox SR. Ankle and Foot Injuries. In: Rosen’s emergency medicine: Concepts and clinical practice. 10th ed. Philadelphia, PA: Elsevier; 2023.

   
   

2. Odak S, Ahluwalia R, Unnikrishnan P, et al. Management of Posterior Malleolar Fractures: A Systematic Review. J Foot Ankle Surg 2016; 55:140.

   
   

3. Donken CC, Al-Khateeb H, Verhofstad MH, van Laarhoven CJ. Surgical versus conservative interventions for treating ankle fractures in adults. Cochrane Database Syst Rev 2012; :CD008470.

   
   

4. Eiff, M., Hatch, R., & Higgins, M. Ankle Fractures. In: Fracture Management for Primary Care and Emergency Medicine. 4^th ed. Philadelphia, PA: Elsevier; 2020