A Novel Electromechanical Intramedullary Nail System for Limb Lengthening.

Background/Purpose of the Study: Many methods have been developed to treat leg length discrepancies. Extensible intramedullary nails are the most commonly used systems. However, complications such as excessive distraction, blockage of the nail, aditional surgery, uncontrolled lengthening and much pain occur during the use of these systems, and the desired success rate cannot be achieved. This study aims to develop a new extensible intramedullary system with two mechanisms (electronical and mechanical) for femur and tibia that treats leg length inequalities in a way that allows lengthening without complications as much as possible and does not require a second surgical intervention. It was planned to perform basic mechanical and cadaver functional tests of the new system, which will be designed and developed for this purpose. Methods: The 3D design of the system has been completed with 3D computer software. A compact system has been developed that is mechanically activated by sudden axial loading and electronically activated by a controllable electric motor. Basic mechanical and functional tests of the new system have been performed within a cadaver. Results: The rapid prototype of the system with electronical and mechanical units has been produced. As a result of the mechanical tests (axial loading), the nail was found to be resistant to compression forces. Its application to the cadaver and function tests was successfully performed. Conclusions: We believe that the system we have developed will have advantages, such as working principle, ease of application, controlled lengthening, patient mobility compared to existing leg lengthening methods. The success of the system in practice will be evaluated by in-vivo animal experiments after more detailed mechanical experiments on cadavers. According to the results, it will be ready for human use by performing necessary restorations.