Fig. 1.

a Diagram of lateral aspect of calcaneus. Line 1 represents the primary shear fracture; line 2 represents the secondary compression fracture giving the tongue fragment; line 3 represents the secondary compression fracture of the joint depression type. When there is absence of an anterior secondary fracture, the subtype is 0; b and c The presence of one fracture line extending to either the calcaneocuboid joint or the plantar surface proximal to the joint is subtype 1. d The presence of more than one anterior fracture is subtype 2. e Extensive comminution is subtype 3