What is defined as the working length of an intramedullary (IM) nail?

• A. Distance between the most proximal and most distal screws
• B. Length of the IM nail itself
• C. Distance from the nail tip to the fracture
• D. Distance from proximal end to distal end without screws

Answer: (A)

The working length of an intramedullary nail is the span of the nail between the closest proximal and distal locking screws. This boundary defines the segment that is free to bend and bear load at the fracture site, so the distance between the nearest screws sets the working length. That’s why the best choice is the distance between the most proximal and most distal screws.

The other options don’t define this movable span: the length of the nail itself is a physical size, not the load-bearing segment; the distance from the nail tip to the fracture isn’t the boundary set by screws; and the distance from the proximal to distal end without considering screw positions would not reflect the actual working portion fixed by screws.