Effect of third fragment size and residual displacement on the treatment of closed tibial shaft fractures by intramedullary nailing: A retrospective case series

Objectives: Closed reduction with fixation using an intramedullary nail (IMN) is the traditional treatment of tibial shaft fractures. However, non-union after IMN remains a significant issue in the health care system. Fracture morphology, such as the partial contact area between the main proximal and distal fragments with a free third fragment in Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/ OTA) type 42B fractures, is an important factor that may influence healing rates. We aimed to examine how third fragment dimensions and residual displacement affect union in Group B fractures treated with IMN. Methods: Fifty patients with closed AO/OTA type 42-B fractures underwent closed IMN. Third fragment dimension were measured on the pre-operative radiograph, and residual displacement was measured on the postoperative radiograph. Radiographic fracture healing was evaluated using the modified radiographic union scale for tibia fractures (mRUST) score. The patients had an average age of 40.8 years and were followed up for an average of 39.7 months. Results: Of the 50 included patients, 35 were in the union group and 15 in the non-union group. Third fragment residual displacement showed a statistically significant difference between the union and non-union groups and was inversely correlated with the mRUST score. It also showed strong predictive power for the mRUST score. Fragment dimensions did not differ significantly between union and non-union groups and were not correlated with either union time or the mRUST score. Conclusion: The third fragment residual displacement significantly affected union in closed AO/OTA type B tibial shaft fractures treated with IMN.