Calcaneal fractures are the most common tarsal fracture and can occur in a variety of settings.

Epidemiology

The calcaneus is the most commonly fractured tarsal bone and accounts for about 2% of all fractures ² and ~60% of all tarsal fractures ³.

Pathology

Calcaneal fractures can be divided broadly into two types depending on whether there is articular involvement of the subtalar joint ^2,7,8:

1. extra-articular: 25-30%

   • anterior calcaneal process fracture

   • calcaneal tuberosity avulsion fracture

   • extra-articular body fracture

     • lover's fracture 

   • medial sustentaculum

2. intra-articular: 70-75%

   • intra-articular body fracture

The calcaneus is also a common site of stress fractures, occurring in the posterosuperior aspect.

Another method of classification is as 

• type A fractures: the anterior process of the calcaneus is fractured

• type B: fracture of the mid calcaneus, trochlear process, and sustentaculum tali

• type C: fracture of the posterior tuberosity

Radiographic features

Plain radiograph

Calcaneal fractures are best assessed with a calcaneal series of radiographs, though are often identified on a lateral ankle radiograph if the presentation does not lead the requesting of calcaneal views specifically. The Böhler and Gissane angles are used to assess the severity of calcaneal fractures, and their postoperative appearance is correlated with functional outcomes ¹².

CT

CT is the modality of choice to evaluate calcaneal fracture. It can show the extent and extra- or intra-articular components of the fracture and hematoma along the sole of the foot (Mondor sign). Intra-articular fractures are often classified using the Sanders classification system, which is one of the only systems that correlates well with patient outcome.

Practical points

If bilateral calcaneal fractures are seen, then the spine should also be evaluated for fracture as the mechanism of injury is often a large load to the axial skeleton, such as a fall from height.

If an intra-articular calcaneal fracture is seen, the images should be scrutinized for a lateral malleolar fleck sign (ankle), which raises the likelihood of peroneal tendon instability ¹⁰.