Trimalleolar fractures refer to a three-part fracture of the ankle. The fractures involve the medial malleolus, the posterior aspect of the tibial plafond (referred to as the posterior malleolus) and the lateral malleolus. Having three parts, this is a more unstable fracture and may be associated with ligamentous injury.
- measuring the size of the fracture fragment as a percentage of the total articular surface on the lateral radiograph or sagittal CT is useful as this is one of the indications for internal fixation (although operative threshold is variable)
- articular steps >1 mm are also an indication for internal fixation