A trimalleolar ankle fracture
by definition is an unstable ankle fracture that requires operative fixation.
It includes the the distal fibula( lateral maleolous ), the medial distal end of the tibia( medial maleolous ), and the lower end of the tibia in the back of the ankle ( posterior maleolous ). The medial and lateral maleolous typically need fixation. Posterior maleolous only if >25% of joint