Ankle fracture

Ankle fractures are the most common fractures of the lower extremity and most often result from twisting the ankle. Clinical features include ankle pain and decreased range of motion. If the patient history and physical examination are both consistent with a fracture (e.g., the patient is unable to bear weight on the affected leg), an x-ray is performed. The most important diagnostic consideration is whether the fracture is stable (e.g., isolated malleolar fractures) or unstable (e.g., bimalleolar fracture). Unstable fractures require surgery, whereas stable ones can be treated conservatively with a short leg cast.

• Eversion or inversion injury
• Direct trauma
  • Crush injury
  • Axial loading (e.g., fall from a height, motor vehicle collision)

Types of ankle fractures ^[1]

• Lateral malleolar fracture
• Medial malleolar fracture
• Posterior malleolar fracture
• Bimalleolar fracture: fractures of the lateral and medial malleoli
• Trimalleolar fracture: fractures of the lateral, medial, and posterior malleoli
• Pilon fracture: fracture of the distal tibia involving the articular surface of the talocrural joint
• Maisonneuve fracture: fracture of the proximal fibula associated with disruption of the distal tibiofibular syndesmosis and medial malleolar injury (i.e., medial malleolar fracture, deltoid ligament rupture) ^[2]
• Other: Volkmann triangle refers to an avulsion fracture of the posterolateral tibial lip

Ankle fracture stability ^[3]

The ankle becomes increasingly unstable with worsening severity of injury. Generally, fractures at two or more sites are unstable.

• Usually stable: isolated lateral malleolar fracture or isolated medial malleolar fracture
• Usually unstable: posterior malleolar fracture, bimalleolar fracture, Maisonneuve fracture
• Always unstable: trimalleolar fracture, pilon fracture

Weber classification of ankle fractures ^[1]

The Weber classification categorizes ankle fractures according to the level of the fibular fracture in relation to the distal tibiofibular syndesmosis.

• Weber A: lateral malleolar fracture below the syndesmosis
  • Intact syndesmosis and deltoid ligament
  • Possible medial malleolar fracture
  • Usually stable
• Weber B: fibular fracture at the level of the syndesmosis
  • Possible syndesmotic injury and/or deltoid ligament injury
  • Variable stability
• Weber C: fibular fracture above the syndesmosis
  • Ruptured syndesmosis, torn interosseous membrane
  • Medial malleolus fracture and/or deltoid ligament tear
  • Unstable

Maisonneuve fractures are considered Weber C fractures. ^[1]

• Local pain, swelling and hematoma
• Tenderness, especially in the area of the malleoli, the syndesmosis, and the posterior aspect of the ankle joint
• Restricted range of movement
• Skin abnormalities (lacerations, discolorations, tenting, or blistering)
• If separation of the ankle mortise elements occurs: lateral displacement of the foot
• In some cases, accompanying injury (e.g., fracture of the proximal fibula, knee, or foot)

Clinical evaluation ^[1]

Perform the following prior to imaging as abnormalities can affect urgent management (see “Approach” in “Treatment”):

• Neurovascular exam
  • Assess dorsalis pedis and posterior tibial artery pulses and distal capillary refill time.
  • Examine motor and sensory function of the lower leg (see “Sural nerve injury”, “Tibial nerve injury”, and “Peroneal nerve injury”).
• Skin exam: Evaluate for laceration, tearing, and tenting.
• Associated injuries: Examine the foot and knee.

Examine the entire length of the fibula in patients with ankle pain to evaluate for a Maisonneuve fracture. ^[1]

Ottawa ankle and foot rules ^[4][5]

These criteria are used to determine the need for X-rays in patients presenting to the emergency department (ED) with traumatic ankle and/or foot injuries. ^[4][5]

• Ankle x-rays are indicated for pain in the malleolar region PLUS any of the following:
  • Tenderness along the posterior distal 6 cm of the:
    • Lateral malleolus
    • OR medial malleolus
  • Inability to weight-bear both immediately post-injury AND for at least 4 steps in the ED
• Foot x-rays are indicated for pain in the midfoot region PLUS any of the following:
  • Tenderness at the:
    • Base of the 5^th metatarsal
    • OR the navicular bone
  • Inability to weight-bear both immediately post-injury AND for at least 4 steps in the ED

X-ray ^[1]

• 3-view plain ankle x-ray: anteroposterior (AP); , lateral and mortise (oblique) views
  • Evaluate for radiographic fracture signs, displacement, and dislocation.
  • Compare joint spaces between the talus and medial malleolus, talus and lateral malleolus, and talus and tibial plafond.
  • Evaluate the ring-like structure surrounding the talus.
• Tibia fibula x-ray: AP and lateral views to evaluate for pilon or Maisonneuve fracture

Advanced imaging ^[1]

• CT: may be obtained for inconclusive x-rays or preoperative planning
• MRI: may be indicated for diagnosis of associated tendon/ligament injuries

• Ankle sprain
• Foot fracture
• Stress fracture
• Tarsal tunnel syndrome
• Arthritis (e.g., osteoarthritis, gout, pseudogout, septic arthritis)
• Achilles tendon rupture
• Charcot joint

The differential diagnoses listed here are not exhaustive.

Approach ^[1]

• Immobilization and disposition: depends on fracture type and classification (See “Overview of ankle fracture management.”)
• Weight-bearing: Most ankle fractures are non-weight-bearing (NWB) except for isolated Weber A fractures which can be weight-bearing as tolerated (WBAT).
• Urgent interventions
  • Perform emergency fracture reduction if there is gross deformity with skin tenting or neurovascular compromise.
  • Administer empiric IV antibiotics for open fractures without delay.
  • Assess for other reasons for urgent orthopedic consultation for fractures.

Stable, isolated, nondisplaced fractures can be initially managed with immobilization and orthopedic follow-up within 48 hours.

Repeat the neurovascular exam after reduction and again after immobilization.

Overview ^[1]

Conservative treatment ^[1]

See “Conservative treatment of fractures” for further details.

• Indications: stable, closed, isolated malleollar fractures
• Definitive management: short leg cast or walking boot for 4–6 weeks

Surgical treatment ^[1]

• Indications
  • Unstable fractures (e.g., displaced fractures); See “Classification” for other types of unstable fractures.
  • Open fractures
• Definitive management
  • Open reduction and internal fixation
  • External fixation

• General complications of fractures
• Damage to the peroneal nerve or saphenous nerve
• Posttraumatic osteoarthritis

We list the most important complications. The selection is not exhaustive.