Tip-apex distance and calcar-referenced tip-apex distance used as a predictor of screws cutout from the femoral head

Abstract

Intertrochanteric fracture, a common kind of injury in orthopaedic surgery, often requires surgical intervention, especially the unstable ones. Since far back in 1995, Baumgaertner et al. recommended using the distance between the screw tip and femoral head apex(tip-apex distance, TAD)as a predictor of the risk of lag screw cutout, the importance of TAD has been recognized by orthopaedic surgeons. This concept has been widely accepted in practice, and even used as a standard in determining the helical blade position. It is not clear, however, whether the helical blade system is equal to lag screws in terms of TAD. After the limitations of TAD had been reported, Kuzyk et al. proposed a tip-apex distance referenced from the calcar(Cal-TAD)as a predictor of lag screw cutout to improve the concept further. In this article, these concepts and the latest clinical applications of TAD and Cal-TAD are reviewed based on the publications available. Key words: Hip fractures; Fracture fixation, internal; Bone nails; tip-apex distance; Calcar referenced tip-apex distance