The 3.9 mm Interlocking Screw is a fully threaded cortical screw engineered for use in interlocking intramedullary nail systems, especially for large bone fixation. Made from high-strength stainless steel or titanium alloy, it features a 3.9 mm outer diameter for enhanced engagement in dense cortical bone and provides secure, anti-rotational and axial locking for the intramedullary nail.

These screws typically include a self-tapping tip for ease of insertion without requiring pre-tapping, although self-drilling variants are also available depending on the surgical system. The thread design ensures excellent cortical grip, making them ideal for stabilizing heavy load-bearing bones, such as the femur and tibia, in adult patients.

Available in various lengths, the 3.9 mm interlocking screw is used through preconfigured holes in the nail and can be inserted proximally and/or distally, depending on the fracture location and nail design.