- includes the tounge frx and joint depression frx;
- results from axial force that is maintained after the primary frx line occurs;
- posterolateral aspect of talus impacts on posterior facet resulting in explosion of lateral wall that may extend as far laterally as the calcaneocuboid joint;
- if load is more horizontal, secondary frx line will exit just behind posteior facet which results in joint depression type of injury;
- resultant free lateral fragment of posterior facet separates from tuberosity fragment;
- this superolateral fragment is also known as semilunar fragment
Pathoantomy of intra-articular articular fractures of the calcaneus.