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- Discussion:
    - 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

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Pathoantomy of intra-articular articular fractures of the calcaneus.