Predictors of nonunion for transverse femoral shaft fractures treated with intramedullary nailing: a SIGN database study

INTRODUCTION: Nonunion is a common postfracture complication resulting in decreased quality of life for patients in resource-limited settings. This study aims to determine how age, sex, injury mechanism, and surgical intervention affect the rate of nonunion in transverse femur fractures treated with a SIGN intramedullary nail (IMN). METHODS: A retrospective study was conducted using the SIGN online surgical database. All patients older than 16 years with simple transverse (<30 degrees), open or closed, femur fractures treated using a SIGN IMN between 2007 and 2021 were included. Our primary outcome of nonunion was measured with the modified Radiographic Union Scale for Tibial fractures (mRUST); scores ≤9 of 16 defined nonunion. The secondary outcome was squat depth. Outcomes were evaluated at follow-up appointments between 240 and 365 days postoperatively. Univariate and multivariate analysis were used for statistical comparison. RESULTS: Inclusion criteria were met for 182 patients. The overall radiographic union rate was 61.0%, and a high proportion (84.4%) of patients could squat with their hips at or below the level of their knees. Older age, retrograde approach, and fracture distraction were associated with nonunion, but sex, injury mechanism, and other surgical variables were not. CONCLUSION: Poor reduction with fracture distraction was associated with a higher rate of nonunion. Loss of follow-up may have contributed to our overall union rate; however, we observed high rates of functional healing using the SIGN IMN. LEVEL OF EVIDENCE: IV.