Radiographic outcomes and factors affecting nonunion after intramedullary nailing in femur segmental fracture: a multicenter study

Factors affecting the outcomes of femoral shaft segmental fractures are currently unknown. We evaluated the outcomes after intramedullary (IM) nail fixation and investigated the factors affecting nonunion in femoral shaft segmental fractures. A total of 38 patients who underwent IM nail fixation for femoral shaft segmental fractures (AO/OTA 32C2) at three university hospitals with a minimum 1-year follow-up was reviewed retrospectively. All patients were divided into the union group (n = 32) and the nonunion group (n = 6). We analyzed smoking status, diabetes mellitus, location of the segmental fragment, segment comminution, filling of the IM nail in the medullary canal, residual gap at the fracture site, use of a cerclage wire or blocking screws as factors that may affect the surgical outcome. In the union group, the average union time was 5.4 months (4–9 months). In the nonunion group, five cases underwent additional surgery at an average of 7.2 months (5–10 months) postoperatively, and one case was asymptomatic and followed-up without surgery. In the comparison of the union and nonunion group, insufficient canal filling of the IM nail (union: 25.0%, nonunion: 83.3%, p = 0.012) and residual gap at the fracture site after reduction (union: 31.3%, nonunion: 83.3%, p = 0.027) showed a significant difference. In multivariate analysis, insufficient canal filling of the IM nail was found to be a factor affecting nonunion, with an odds ratio of 13.3 (p = 0.036). After IM nail fixation for femoral shaft segmental fractures, a relatively high nonunion rate (15.8%) was observed. Factors affecting nonunion were insufficient canal filling of IM nail and residual gap of fracture site.