Impact of localization, size, displacement and open/closed reduction of third fragment on union in femoral shaft fractures treated with locked intramedullary nails

INTRODUCTION AND AIM: This study aims to evaluate the impact of the localization, size, and displacement level of the third fragment in 32-B1, 32-B2, and 32-B3 femoral shaft fractures treated with locked intramedullary nails according to the AO/OTA classification, as well as the effect of open or closed reduction of the fracture on union. METHOD: Seventy-six patients with 32-B1, 32-B2, and 32-B3 femoral shaft fractures treated with locked intramedullary nails were reviewed retrospectively. The vertical size, transverse distances, and localization of the third fragment were recorded from initial postoperative radiographs. The type of reduction (open or closed) was noted. Union status was evaluated based on the RUSF score from postoperative follow-up radiographs. Patients with pathological fractures and less than 2 years of follow-up were excluded. RESULTS: The vertical size and transverse displacement of the fragment did not significantly affect union time. Nonunion rates were significantly lower for fractures with the third fragment located posteromedially-posteriorly compared to anterolateral-lateral localization. The 6-month RUSF scores were higher in the posteromedial-posterior group, indicating faster union, but there was no significant difference in 12-month scores between groups. CONCLUSION: Although there was no statistically significant effect of the vertical size and transverse displacement of the third fragment on nonunion, it was observed that the fragment localized anterolateral-laterally was more significantly associated with nonunion. While a significantly higher rate of nonunion was observed in patients treated with open reduction alone, logistic regression analysis showed that the effect of open reduction on nonunion could not be significantly demonstrated according to the fracture localization.