Advancing Intramedullary Nailing: A Novel Radiation-Free Multi-Angle Targeting Method for Dynamic Distal Locking Screw Holes: A Technical Feasibility Study

Abstract Purpose Distal locking during intramedullary nailing remains technically challenging because of nail deformation, limited visual feedback, and reliance on fluoroscopy, resulting in prolonged operative time and radiation exposure. Dynamic distal locking holes further complicate targeting due to allowable angular variability. This study proposes and evaluates a radiation-free, multi-angle distal locking approach integrating an intramedullary endo-transilluminating (iMET) optical positioning device with a cannulated boring screw. Methods An in vitro feasibility study was conducted using five porcine femurs. The iMET device provided real-time optical guidance for screw hole localization. A custom cannulated boring screw enabled combined drilling and locking. Locking performance was assessed at 15°, 45°, 60°, and 90° insertion angles. Procedural time and accuracy were recorded and compared with historical fluoroscopy-guided data. Results Successful distal locking was achieved in all specimens and at all tested angles. The mean total locking time was 46.8 ± 16.5 s, which was substantially shorter than the reported fluoroscopy-guided time (246 ± 108 s). The 90° locking configuration required the shortest time (27–28 s), whereas the 60° configuration required the longest (68 s). No ionizing radiation was used during any procedure. Conclusions The proposed iMET-guided cannulated boring screw system demonstrates the technical feasibility of a radiation-free multi-angle distal locking approach in a controlled in vitro setting. This approach may offer a potential radiation-free solution for multi-angle distal locking, although its clinical applicability requires further validation. Further studies, including cadaveric and clinical validation, are required to confirm its translational applicability.