Ratio of the unfixed distal segment: A/B. A: Distance from the tip of the nail to the intercondylar notch in the AP view, B: main distal fragment length from the proximal fracture line to the intercondylar notch in the AP view. Ratio of the IM canal diameter to nail size at the level of fracture: C/N. C: IM canal diameter at the level of fracture in the AP view, N: nail size in the AP view.