Trimallelor Fractures:

Bimallelor fracture involve both the medial mallelous of the tibia and the distal fibula.  The third malleloi is the posterior tip of the articular surface of the tibia. Can result in instability in the posterior and lateral directions along with external rotation.

Some indications for Open Reduction Internal Fixation when the posterior mallelous is fractured are:

• > 25% of the posterior articular surface being involved.
• Fractures that allow posterior subluxation of the talus
• Fractures that are displaced more than 2 mm
• Fractures that can not be reduced satisfactorily.