This study examined the outcomes of exchange nailing for the hypertrophic nonunion of femoral shaft fractures treated with intramedullary nailing as well as the factors affecting the treatment outcomes.

From January 1999 to March 2015, 35 patients, who had undergone intramedullary nailing with a femoral shaft fracture and underwent exchange nailing due to hypertrophic nonunion, were reviewed. This study investigated the time of union and complications, such as nonunion after exchange nailing, and analyzed the factors affecting the results.

Bone union was achieved in 31 cases (88.6%) after exchange nailing and the average bone union period was 22 weeks (14–44 weeks). Complications included persistent nonunion in four cases, delayed union in one case, and superficial wound infection in one case. All four cases with nonunion were related to smoking, three of them were distal shaft fractures, and one was a midshaft fracture with underlying disease.

Exchange nailing produced satisfactory results as the treatment of hypertrophic nonunion after intramedullary nailing. Smoking is considered a factor for continuing nonunion even after exchange nailing. In the case of a distal shaft, where the intramedullary fixation is relatively weak, additional efforts are needed for stability.