- Discussion:
- the primary frx line begins in the sinus tarsi and then extends obliquely and posteriorly to exit the medial wall;
- hence the frx, travels antero-lateral to posteromedial;
- the primary frx line usually extends anterior to the angle of Gissane but in some cases may extend anteriorly as far as the calcaneocuboid joint;
- posteriorly, primary fracture line moves medially, separating the calcaneus into two main fragments;
- tuberosity fragment is the anterolateral fragment (lateral to center of talus);
- sustentacular fragment lies medial to the center of the talus;
- w/ axial loading, the tuberosity moves lateral, and the sustentacular fragment moves medially;
- primary fracture line may take one of three paths:
- lateral to posterior facet (from impact on pronated foot)
- through posterior facet (neutral foot position)
- secondary frx line will appear beneath facet, exiting posteriorly and resulting in a tounge type fracture;
- anteromedial to the posterior facet:
- from impact on supinated foot;
- primary saggital frx line enters calcaneal sulcus, anteriomedial to posterior facets, & entire posterior facet remains intact;
- two part joint depression or tongue frx may result;
- cautions:
- radiographs will fail to show the anterior extension of the primary frx line in about one half of cases

Pathoantomy of intra-articular articular fractures of the calcaneus.