A medial malleolus fracture is a fracture of the lowest part of the tibia. Fractures of the medial malleolus may be isolated, but they are more commonly associated with fractures in other parts of the ankle. A medial malleolus fracture that is not out of place (nondisplaced) can be treated with a short leg cast or walking boot.

An isolated fracture of the medial malleolus generally occurs when the foot is forcefully rolled inwards or outwards. 2  When the foot rolls inwards, this causes a compression of the medial malleolus on the inner side of the ankle. When the foot rolls out, this pulls tension on the medial malleolus, which can also cause a fracture.