Figure 1. Traditional interlocked IM nails are designed with slightly oversized, unthreaded interlocking holes (a); this clearance facilitates screw insertion but also allows for construct toggle to occur. Interposing a collar between the screw head and nail with the addition of nail hole threads creates a fixed angle device (b). Overdrilling the near cortex increases the compliance of the angle-stable design proportional to the amount of overdrilling (c).