Third fragment femoral shaft fracture: A retrospective analysis of complications and predictive factors for non-union and delayed union

Introduction: Diaphyseal femur fractures are relatively common, and up to 39% of these cases involve a third fragment. These types of fractures present a unique challenge due to their high risk of non-union, reported in up to 14% of cases. Despite their frequency, there is still no consensus on the optimal management of the third fragment in these fractures. The purpose of this retrospective study was to compare the clinical and radiological outcomes of patients who underwent reduction of the third fragment with those who did not, to determine the characteristics of the third fragment that warrant reduction, and to suggest the best approach. The hypothesis is that an open reduction of the third fragment is to be avoided as it increases the risk of non-union. Material and methods: This retrospective monocentric study analysed clinical data from patients diagnosed with diaphyseal femur fractures at our Unit between 2010 and 2022. Radiological data encompassed the length and width of the third fragment, the fracture gap, its proximity to the proximal and distal cortex, the greatest cortex-to-cortex distance, and the orientation of the third fragment. Other factors considered included patient age, BMI, sex, type of surgery performed, fracture fixation method, occurrence of complications, specific complication types, incidence of mortality, and duration of follow-up. Results: Seventy patients were included in the study; 24 patients underwent osteosynthesis with plates and screws, while 46 patients were treated with intramedullary nailing. Descriptive analysis revealed no statistically significant difference in the characteristics of the third fragment between patients who experienced complications and those who did not. Surgical technique for osteosynthesis (plates and screws Vs intramedullary nailing) also showed no statistically significant differences, conversely the open reduction and synthesis of the third fragment is a statistically significant complication predictor. Conclusion: The management of the third fragment remains a challenge. In our series of patients third fragment characteristics and type of osteosynthesis did not influence the risk of complications. However, the determining factor was found to be the open reduction of the third fragment. Level of evidence: IV