Ankle fracture, Weber A

A transverse avulsion of the lateral malleolus below the level of the joint, caused by the lateral ligaments pulling on the tip. The syndesmosis and the mortise are intact, so the ankle is almost always stable.

Mechanism

Supination–adduction (inversion) injury.

Clinical findings

• Tenderness at the tip of the lateral malleolus; Ottawa rules decide who needs an X-ray.
• Check the medial malleolus: a vertical medial fracture makes it unstable.

Imaging

• Ottawa ankle rules first: X-rays only if indicated.
• AP, mortise and lateral of the ankle.

• AP, mortise and lateral views. Medial clear space ≤ 4 mm and equal to the superior clear space = stable mortise.

Classification

44A1

Isolated infrasyndesmotic lateral injury.

44A2

With a medial malleolus fracture.

44A3

With a posteromedial fracture.

Types shown in 3D

44A1

Isolated infrasyndesmotic lateral injury (tip avulsion). Stable: walking boot.

44A2

With a fracture of the medial malleolus: the talus pushes it off medially and upwards (vertical shear line). Unstable: fix the medial side, often with an antiglide plate; look for impaction of the medial plafond.

44A3

With a posteromedial fracture of the tibia.

Treatment

Non-operative

Isolated Weber A: functional treatment in a walking boot or brace, weight bearing as tolerated for 4–6 weeks.

Operative

Only with a displaced medial malleolus (vertical shear: buttress plate or screws) or a large displaced tip fragment.

Aftercare

Early weight bearing, physiotherapy for proprioception.

Complications

• Missed osteochondral lesion of the talus
• Ongoing lateral instability