- 2 types: Avulsion and Compression Fractures
 
  - Avulsion Fractures:
        - is the more common of the 2 fractures;
        - mech: adduction, plantarflexion, & tension placed on bifurcate ligament;
        - bifurcate ligament:
              - this ligament connects the anterior process of the calcaneus to both the cuboid and navicular bones;
              - inversion stress of the foot will result in stretch of this ligament or avulsion fracture of the anterior process;
 
- Compression Fracture:
     - mechanism of injury is forceful abduction of forefoot w/ compression of the calcaneocuboid joint;
     - anterior articular surface of calcaneus is frx, & variably sized fragment can be displaaced superiorly and posteriorly, resulting in joint incongruity;
     - Exam:
           - pain & tenderness may be located in region of sinus tarsi
           - point of maximal tenderness will be 2 cm anterior and 1 cm inferior to anterior talofibular ligament, which should help distinguish this injury from a lateral ankle sprain;
           - X-ray:
                 - lateral x-ray of hindfoot will best demonstrate compression type of frx;
                 - lateral oblique views most frequently will show avulsion fracture;
                 - small inconsistent ossicle, calcaneus seconndatrium, lies just adjacent to anterior process and must not be confused with fresh fracture;
                 - Treatment:
                        - when diagnosed early, immobilized in short leg cast for 4 weeks; 
                        - full recovery may take 6 to 9 months
 

Anterior process fracture of the calcaneus. 

Surgical excision for anterior-process fractures of the calcaneus.