Musculoskeletal · Orthopedic Trauma
The facts most likely to be tested
The Ottawa Ankle Rules mandate radiography if there is bone tenderness at the posterior edge or tip of the lateral or medial malleolus.
A bimalleolar fracture involves both the medial and lateral malleoli and is inherently unstable, requiring open reduction internal fixation (ORIF).
The Lauge-Hansen classification system categorizes ankle fractures based on the mechanism of injury and the position of the foot at the time of impact.
A Maisonneuve fracture is a spiral fracture of the proximal fibula associated with an unstable ankle injury and disruption of the syndesmosis.
Weber C fractures occur proximal to the syndesmosis and are associated with significant syndesmotic injury and ankle instability.
Talar tilt or mortise widening on plain radiographs indicates a disruption of the deltoid ligament or syndesmosis, necessitating surgical consultation.
Neurovascular compromise, specifically involving the posterior tibial artery or peroneal nerve, is a limb-threatening complication requiring immediate reduction of the fracture-dislocation.
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A 28-year-old male presents to the emergency department after a soccer injury involving an eversion force to his left ankle. Physical examination reveals significant medial ankle tenderness and swelling. Radiographs show a widened medial clear space and a spiral fracture of the proximal fibula. The patient has intact distal pulses and sensation.
What is the most likely diagnosis?
Maisonneuve fracture
The combination of a proximal fibular fracture and medial ankle injury (widened medial clear space indicating deltoid ligament/syndesmotic disruption) is the classic presentation of a Maisonneuve fracture, which is tested as a high-yield 'missed' injury.
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High yield triage
Etiology / Epidemiology
Common in low-energy trauma (twisting) or high-energy trauma (falls/MVA). Osteoporosis is a major risk factor in elderly patients.
Clinical Manifestations
Presents with pain, swelling, and inability to bear weight. Ottawa Ankle Rules guide imaging necessity.
Diagnosis
Ankle series radiographs (AP, lateral, mortise view) are the gold standard. Medial clear space >4mm indicates syndesmotic instability.
Treatment
Open Reduction Internal Fixation (ORIF) for unstable fractures. Do not weight bear until cleared by orthopedics.
Prognosis
Risk of post-traumatic arthritis is high. Anatomic reduction is the primary predictor of long-term function.
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Epidemiology & Etiology
Ankle fractures are among the most common orthopedic injuries, often resulting from supination-external rotation mechanisms. Incidence peaks in young males (sports) and elderly females (osteoporosis). High-energy mechanisms require evaluation for associated proximal fibular fractures (Maisonneuve fracture).
Pertinent Anatomy
The ankle mortise consists of the distal tibia, distal fibula, and talus. The syndesmosis (tibiofibular ligaments) provides critical stability. Disruption of the deltoid ligament often accompanies lateral malleolar fractures, rendering the ankle unstable.
Pathophysiology
Fractures are classified by the Lauge-Hansen system based on foot position and force direction. Unstable injuries involve disruption of both the lateral and medial columns. Failure to restore the talocrural joint congruity leads to abnormal contact pressures and rapid cartilage degradation.
Clinical Manifestations
Patients present with localized bony tenderness, ecchymosis, and deformity. Neurovascular compromise (distal pulse loss, paresthesia) is a surgical emergency. Use Ottawa Ankle Rules: order X-rays if pain in the malleolar zone plus inability to bear weight or tenderness at the posterior edge of the malleoli.
Diagnosis
Ankle series radiographs (AP, lateral, and mortise views) are mandatory. The mortise view is essential to assess the medial clear space; a width >4mm is highly suggestive of deltoid ligament rupture and syndesmotic instability. CT is reserved for complex pilon fractures or preoperative planning.
Treatment
Stable, non-displaced fractures are managed with short leg cast or walking boot. Unstable fractures require ORIF to restore joint anatomy. Weight-bearing is strictly prohibited until radiographic healing is confirmed. Post-operative management includes DVT prophylaxis in high-risk patients.
Prognosis
Long-term outcomes depend on the quality of reduction. Post-traumatic arthritis is the most common complication, occurring in up to 30-40% of severe injuries. Patients require long-term monitoring for chronic pain and functional deficits.
Differential Diagnosis
Ankle Sprain: tenderness over ligaments, not bone
Maisonneuve Fracture: proximal fibular fracture with syndesmotic injury
Pilon Fracture: high-energy distal tibial plafond involvement
Talar Neck Fracture: high-energy axial load with risk of avascular necrosis
Osteochondral Lesion: persistent pain after trauma, often missed on initial X-ray