Calcaneal malunions: results of a prognostic computed tomography classification system.

Following nonoperative treatment of calcaneal fractures, some patients may develop a disabling malunion with associated posttraumatic arthritis of the subtalar joint, impingement of the peroneal tendons, and hindfoot mal-alignment. We present a computed tomography classification system for calcaneal malunions which guides treatment and is of prognostic significance. A prospective study was performed using this classification system on a series of 26 malunions treated over a 45-month period. Three distinct types of malunions were identified: type I, lateral wall exostosis without subtalar arthrosis; type II, lateral wall exostosis with subtalar arthrosis; and type III, lateral wall exostosis, subtalar arthrosis, and a varus malunion. The surgical treatment was determined by a protocol based on the specific type of malunion encountered. Results were evaluated using the Maryland Foot Score. There were 18 excellent, 5 good, and 3 fair results. Although outcomes deteriorated as malunion complexity increased, significant clinical improvement as a result of reconstructive surgery was noted in even the worst types of malunion. This algorithm is consistent, prognostic, and useful for the orthopaedic surgeon presented with a symptomatic calcaneal malunion of one of these types.