*Calcaneus Fractures DOI: http://dx.doi.org/10.5772/intechopen.114132*

displacement or subtalar joint depression are classified as type II and comminuted fractures as type III. Lauder et al. [28] compared the Sanders classification to the Crosby-Fitzgibbons system and found that the Crosby-Fitzgibbons system had significantly greater interobserver reliability than the Sanders classification. Swords et al. [29]. compared the Crosby-Fitzgibbons to the Eastwood and Sanders classifications and found no significant difference in the ability to predict patient functional

**Figure 4.** *AO/OTA fracture classification of calcaneus fractures [30].*

outcomes using the Musculoskeletal Functional Assessment. However, the Sanders classification trended toward significance and had the highest predictive capability of functional outcomes.

The Müller/AO/OTA classification denotes the calcaneus as 82 and subdivides it into 82A, 82B, and 82C (**Figure 4**) [30]. Extraarticular fractures are classified as 82A, which is further divided into 82A1 for avulsion, posterior tuberosity, or extraarticular tongue-type fractures and 82A2 for extraarticular body fractures. Tongue-type fractures that exit into the posterior facet are classified as 82B1, 82B2 if there is associated joint depression, or 82B3 if highly comminuted. Complete articular fractures are classified as 82C. When there is joint depression with a single fracture line through the posterior facet, it is 82C1. If there is joint depression with two fracture lines (Sanders III equivalent), it is 82C2 and if highly comminuted (Sanders IV), 82C3.

The Regazzoni classification is a Swiss model for classifying calcaneal fractures [10, 31]. The Regazzoni classification system is based on coronal CT images. Type A fractures are peripheral fractures that are either extraarticular (A1), avulsion fractures of the sustentaculum (A2), or fractures of the anterior process (A3). Type B fractures are fractures involving the talocalcaneal joint. Type B fractures

**Figure 5.** *Regazzoni classification of intra-articular calcaneal fractures [32].*

#### *Calcaneus Fractures DOI: http://dx.doi.org/10.5772/intechopen.114132*

can be those with single posterior facet fracture lines (B1), multiple posterior facet fractures (B2), and fractures involving the tarsal sinus (B3). Type C fractures are fractures of the talocalcaneal and calcaneocuboid joints. Single fracture lines in both joints constitute a C1 fracture. If one joint has multiple fracture lines or the tarsal sinus is involved, it is termed a C2 fracture. If multiple fracture lines involve both joints, it is a C3 fracture (**Figure 5**).

Rubino et al. [32]. compared the Essex-Lopresti, AO/OTA, Swiss Regazzoni, and Sanders classifications utilizing the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot score, Creighton Nebraska Health Musculoskeletal Functional Assessment (MFA) Questionnaire, and other scores to determine the classification system with the best outcomes. Overall, the CT-based classifications had the highest prognostic values, particularly the Regazzoni and Sanders classifications.
