The AP view of the left ankle shows a widened medial ankle joint space, which is suggestive of a deltoid ligament tear.

The lateral ankle x-ray shows an undisplaced fracture of the posterior malleolus.

Teaching points:

• The ankle joint space should be uniform. If the medial side is widened, suspect a deltoid ligament injury.
• If there is an isolated fracture of the medial malleolus or a deltoid ligament tear on the ankle AP x-ray but a fracture of the lateral malleolus cannot be observed, image the entire leg to rule out higher fibular fracture, i.e. Maisonneuve fracture.

Reference: www.radiologymasterclass.co.uk