Sanders CT classification of calcaneal fracture

The Sanders classification system is used to assess intraarticular calcaneal fractures, which are those involving the posterior facet of the calcaneus. This classification is based on the number of intraarticular fracture lines and their location on semicoronal CT images. This classification is useful not only in understanding typical fracture patterns of the calcaneus but also in predicting the outcome. As you move from type 1 to type 4 injuries, expected outcomes are progressively worse.

• type 1: includes all intraarticular fractures that have less than 2 mm of articular displacement, regardless of the number of fracture lines/fragments present
• type 2a: involves one primary fracture line that courses through the lateral aspect of the posterior facet; the primary fracture usually assumes a "y" shaped configuration as it exits medially and laterally out of the calcaneal body; this fracture is often accompanied by one or more accessory fracture lines that do not involve the posterior articular facet
• type 2b: involves one primary fracture line that courses through the central aspect of the posterior facet; the primary fracture usually assumes a "y" shaped configuration as it exits medially and laterally out of the calcaneal body; this fracture is often accompanied by one or more accessory fracture lines that do not involve the posterior articular facet
• type 2c: involves one primary fracture line that courses through the medial aspect of the posterior facet and is accompanied by a transverse fracture through the body of the calcaneus; this fracture is often accompanied by one or more accessory fracture lines that do not involve the posterior articular facet
• type 3ab: involves two primary fracture lines, one coursing through the lateral aspect of the posterior facet and the second through the central aspect; this subtype usually presents with depression of the central fragment; the two primary fracture lines may be accompanied by additional accessory fracture lines that do not involve the posterior articular facet
• type 3ac: involves two primary fracture lines, one coursing through the lateral aspect of the posterior facet and the second through the medial aspect; this subtype usually presents with depression of the central fragment. The two primary fracture lines may be accompanied by additional accessory fracture lines that do not involve the posterior articular facet
• type 3bc: involves two primary fracture lines, one coursing through the central aspect of the posterior facet and the second through the medial aspect; this subtype usually presents with depression of the central fragment; the two primary fracture lines may be accompanied by additional accessory fracture lines that do not involve the posterior articular facet
• type 4: involves three or more primary fracture lines with greater than 2 mm of articular displacement, and are therefore severely comminuted