Ankle Fractures

Ankle fractures typically refer to a break in either malleolus, although there are multiple possible fracture sites in the bony structure of the foot. Over the age of 65 they are more common in white women and present as an isolated fibular fracture. Under the age of 65 they are more common in males and present as a lateral malleolus fracture. The most common mechanism is usually a low-energy fall, with the next most common causes being: an inversion injury to the ankle, sporting injury, fall down the stairs, fall from a height or road traffic accident. There is increased risk of ankle fractures in those with a history of osteoporosis or frequent falls.

Diagnostic Factors

• Recent trauma, typically from a low-energy fall
• Pain and swelling, especially over the medial or lateral malleolus and on palpation
• Inability to weight bear
• 'Pop' or other sound heard on fall
• Giving way on fall
• Deformity - typically indicative of dislocation
• Crepitus on range of motion
• Tenderness of the proximal fibula
• Tenting of the skin over the medial malleolus - typically indicative of dislocation

Ottawa Ankle Rules

A diagnostic tool to help decide the need for x-rays. If there is:

• Posterior lateral or medial bony tenderness within 6cm of the distal aspect of the fibula or tibia
• Inability to weight bear 4 steps at the scene or A&E

...then an x-ray should be ordered.

Imaging

Fracture --> X-ray

Comminuted fractures --> CT

Ligament or tendon damage --> MRI

Differential Diagnosis

ATFL or CFL ligament tear presents with minimal lateral malleolar posterior bony tenderness. There may be a positive anterior drawer test or increased talar tilt, but there is rarely significant deformity.

Achilles tendon rupture presents with no malleolar tenderness. There may be a gap in the Achilles tendon or a positive Thompson's test.

Talar fracture is unlikely to present with malleolar tenderness, but there may be a deformity to the ankle and hindfoot.

Syndesmotic disruption is unlikely to present with malleolar tenderness. Test with external rotation and calf squeeze test.