Prophylactic Intramedullary Nailing Following Femoral Lengthening in Congenital Femoral Deficiency: A Retrospective Comparative Study

Background: Fracture of newly formed bone (the regenerate) after EF (External Fixator) removal is a serious complication of bone lengthening in Congenital Femoral Deficiency (CFD). This study aimed to determine whether prophylactic intramedullary nailing (IMN) at the time of EF removal reduces the risk of femoral fractures in CFD and to evaluate its safety. Methods: This retrospective comparative study included 53 CFD patients who underwent femoral lengthening (44 in the IMN group, 9 in the historical no-IMN group). We analyzed the incidence of fractures, infections, and unplanned surgeries. The predictive value of Fischgrund principles and Li classification for fracture risk was evaluated. Results: The fracture rate was 11.3% (6/53). The IMN group had fewer fractures (6.8%) versus the no-IMN group (33.3%, p = 0.054). Surgical treatment risk for femoral fracture was significantly lower in the IMN group (2.3% vs. 33.3%, p < 0.05). Despite complications in the IMN group (4.5% infection rate, 4.5% nail malposition rate, 2.3% hip dislocation), the rate of unplanned surgery was lower than in the no-IMN group (11.4% vs. 33.3%, p = 0.12). Associations between regenerate morphology and subsequent fracture occurrence were observed only in the historical no-IMN group. Prophylactic nailing may provide mechanical support in patients with less mature regenerate. Conclusions: In this retrospective study with a historical comparison group (no-IMN), prophylactic intramedullary nailing was associated with fewer fractures requiring surgery after femoral lengthening with EF in CFD.