Is Subclassification by Number of Fracture Fragments Necessary for Sanders Type IV Calcaneal Fractures?

Background: The Sanders classification is a widely used method for classifying calcaneal fractures. Type IV fractures (>4 fragments) are known to vary in the number of fracture fragments. However, all relevant cases are classified as type IV irrespective of the number of fragments. We investigated the need for evaluation of postoperative prognoses based on radiologic factors and subtypes of Sanders classification type IV fractures. Methods: Fifty-six Sanders type IV calcaneal fractures were enrolled between 2010 and 2018. Patients were divided into two groups according to the number of fragments: four fragments (group 1) and more than four fragments (group 2). Radiologic evaluation was performed using a postoperative recovery percentage calculated from postoperative reduction of the Böhler angle, Gissane angle, and vertical height. Radiologic evaluation was divided into two groups according to postoperative recovery: good and bad recovery groups. American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and visual analog scale (VAS) score were used for clinical outcome evaluation. Results: There was no significant difference in AOFAS ankle-hindfoot score ( P = .909) or VAS score ( P = .963) between groups 1 and 2. However, there was a significant ( P = .001) difference in AOFAS ankle-hindfoot score or VAS score between good and bad recovery groups. Conclusions: Clinical results of Sanders type IV fractures were not related to the number of bone fragments but to the degree of injury to the Böhler angle, Gissane angle, and vertical height. Therefore, subtype classification of type IV calcaneal fractures is superfluous, and it is important to try to restore these parameters during surgery.