Introduction of a modified Degan classification to specify treatment algorithms in fractures of the anterior process of the calcaneus

BACKGROUND: Fractures of the anterior process of the calcaneus are often missed, and their treatments and results receive little attention in the current literature. The aim of this study was to specify treatment algorithms through a modification of the Degan classification. METHODS: Between 2009 and 2019, patients with APC fractures were retrospectively analyzed. The Degan classification was used and modified. Type III fractures were further divided into subgroups A (not displaced) and B (displaced). The type of treatment and complications were recorded. Return to work and posttraumatic osteoarthritis were determined as primary and secondary outcome parameters, respectively. RESULTS: Forty-one patients with 43 fractures were included. Follow-up averaged 35,5 months (range 1,5–152 months). Fractures were eight type I, six type II, 15 type IIIA and 14 type IIIB. The fracture was initially recognized in 29 (70,7%) patients, and missed in 12 (29,3%) patients, respectively. Overall, the delayed diagnosed fractures had a significantly higher complication rate (p < 0,000) than the initially diagnosed fractures and received surgical treatment significantly (p < 0,009) more often. After surgical treatment of 13 type IIIB, one nonunion occurred. Six missed type IIIA fractures were treated surgically after delayed diagnosis because of persistent symptoms. Two type I fractures required arthrodesis of the Chopart joint. Four patients did not return to work during the follow-up (3 missed type IIIA fractures, 1 type II fracture). CONCLUSION: Missed APC type IIIA fractures are at risk to develop complications, which is why computed tomography diagnostics should be performed if there is any clinical suspicion.