The Effect of Pre-Bending Flexible Nails on Outcomes Following Stabilization of Paediatric Forearm Fractures

Background: Potential complications after elastically stable intramedullary nailing (ESIN) of pediatric forearm fractures include nonunion and malunion. Malunion, especially affecting the radial bow, has been linked to poor postoperative forearm rotation. Pre-bending of nails has been cited as a key step to achieve optimal construct biomechanics and maintain reduction. We hypothesise that unlike in larger medullary diameter bones such as the femur, pre-bending of nails for the treatment of paediatric forearm fractures has no effect on postoperative outcomes. Methods: Forearm fractures treated with ESIN to both bones in our tertiary paediatric orthopaedic centre were identified. Exclusions were made for Galeazzi, Monteggia, intra-articular, and pathologic fractures. Radiographic data, including time to union and magnitude and location of radial bow, were recorded. Demographics, implant data, complications, and time to return of forearm rotation were collected through retrospective review of clinical notes. Results: One hundred three eligible patients were identified with 33 receiving pre-bent nails and 70 receiving unbent nails. There were no significant differences in age, sex, or proportion of open fractures between cohorts. Mean location of maximal radial bow was 69% in both cohorts ( P =0.942) and no significant difference in magnitude of maximal radial bow was observed between the pre-bent and unbent cohorts (4.9% vs. 5.3%, P =0.199). Regarding the pre-bent and unbent cohorts there were no significant differences observed in median time to restoration of normal forearm rotational movement (100 vs. 81 d, P =0.452), time to union (44 vs. 42 d, P =0.527), nail diameter used (2.3 vs. 2.2, P =0.138), or complication rates (12% vs. 14%, P =0.911). Conclusions: Pre-bending of the nails before insertion does not have a significant effect on the time to union, restoration of the radial bow, or forearm rotation. As such, this likely represents an unnecessary step in children for whom narrower canal diameters enable a straight nail to provide sufficient cortical contact, stability, and tension to the interosseous membrane. Level of Evidence: Level IV (case series).