Does postoperative immobilization affect final alignment of pediatric femur fractures treated with flexible intramedullary nailing?

Flexible intramedullary nail (FIN) fixation of pediatric femur fractures is a popular method of fixation in children. Typical immobilization options include spica casting, long leg cast, knee immobilizers, or no immobilization and the decision to use each is usually left to surgeon preference. Our primary aim is to evaluate whether different postoperative immobilization status influences outcomes, namely radiographic alignment at the time of healing. A retrospective chart review was conducted of all patients with femur fractures treated with FIN fixation at a pediatric hospital from April 2018 through July 2022. Postoperative immobilization protocols were recorded and separated into two groups, patients who were immobilized (IMM) and patients who were not immobilized (NoIMM). Radiographs were evaluated for fracture alignment immediately following surgery and at the time of healing. Patients demographic, fracture, and postoperative clinical characteristics were compared between the two groups (NoIMM vs. IMM). A total of 41 patients were treated for diaphyseal femur fractures with FINs at our institution during the study period. No significant difference was observed in alignment at healing. Our results suggest that either immobilization or no immobilization after flexible intramedullary nailing of pediatric femoral shaft fractures are viable options when postoperative immobilization status is left to the surgeon's discretion.