Load Transfer in Tibial Intramedullary Nailing: Effects of Fracture Level, Screw Configuration and Nail-Canal Clearance.

Intramedullary nails are widely recognized for their high stabilization capacity and are considered the gold standard for tibial fracture treatment. However, hardware failure, especially of distal screws, is frequently reported, especially in cases involving distal fractures. Although various experimental studies explore screw configurations, few quantify the mechanical loads acting on individual screws at different fracture locations. This study numerically evaluates two fixation systems: one with four screws and another with five, including an additional distal screw (DS3). The results show that the fifth screw significantly reduces von Mises stress, especially in distal fractures, though the improvements in overall stability are less pronounced. The mechanical implications on the inclusion of a clearance between the nail and endosteal surface are assessed. The stresses in the locking screws are significantly higher when the reaming clearance is included in the simulation. Despite mechanical advantages, clinical trade-offs such as increased surgical complexity and radiation exposure must be considered.