Original Locking Rod System Designed for Diaphyseal Fractures of Long Bones.

Introduction: Intramedullary nailing is widely used for long bone fractures. Traditional systems are reliable, but they present some complications regarding lack of modularity or possible growth plate damage. Methods: A novel locking rod-screw system featuring a central rod and a grooved screw with a secondary interlocking mechanism was developed and tested. Mechanical testing followed ASTM F543 and ISO 6475 standards using a 3.0 mm steel alloy prototype. Results: The system withstood mechanical testing >200,000 cycles at loads up to 200 N with no rates of failure or loosening, significantly outperforming other implants of the same size (3.0 mm TENS). Conclusions: The proposed implant demonstrates superior biomechanical performance in vitro, enabled by its unique hollow screw and secondary locking configuration. This modular and minimally invasive system shows promise for use in cases of smaller long bones, personalized paediatric fractures, and all types of diaphyseal fractures, but does warrant in vivo validation.