Biomechanical Evaluation of the Surgical Implant Generation Network (SIGN) Intramedullary Tibial Nail

INTRODUCTION: The orthopaedic community has become increasingly cognizant of the disparity that exists in healthcare throughout the developing world. Annually, there are nearly five million deaths worldwide due to traumatic injuries; a number approximating that of HIV/AIDS, malaria and tuberculosis combined. Motor vehicle trauma accounts for a large proportion of these deaths, and for every death there are many more left permanently disabled. In developing nations, significant rural-to-urban population shifts and industrialization are causing significant increases in the number of industrial and motor vehicle accidents. These trends are expected not only to continue but to accelerate substantially. Of all long bone fractures sustained during accidents tibial fractures are the most common. In developing countries the optimum treatment method for complex fractures of the tibia remains controversial. Options for stabilization include cast immobilization, external fixation, open reduction and plate fixation, and intramedullary (IM) nailing. IM devices have become the most popular implant choice in developed nations. However, the significant costs and the equipment needed to place these devices have made their use challenging in the developing world. In 1999, the Surgical Implant Generation Network (SIGN) of Richland, Washington, was created as a non-profit humanitarian organization aiming to provide quality orthopaedic equipment and care at little or no cost to developing nations in need. To date, more than 36,000 patients have been treated with the SIGN IM femoral or tibial nail. The SIGN tibial system is a solid IM nail with interlocking capability. Proximal and distal cross-locks are placed using a mechanical aiming device thereby eliminating the need for costly, cumbersome and largely unavailable C-arm systems. A recent series published by Shah et al demonstrated a 90% union rate in open tibial fractures treated with the SIGN system. To our knowledge, no previous study has evaluated the mechanical properties of the SIGN tibial nail system. The purpose of this study was, therefore, to elucidate the mechanical properties of this solid nail and compare them with those of a commonly used North American hollow construct.