To analyze clinical and radiologic results and to identify the relevant factors indicating the cutting out of lag screw for the treatment of peritrocanteric fracture of the femur using a gamma nail.

Eighty-three peritrochanteric fractures, by the Evans classification, were evaluated clinically to assess the walking capacity. Radiologically bone union, reduction status, sliding, position of the lag screw, bone density, displacement, and tip-apex index (TAD) were evaluated. The relationship between the cutting out of lag screw and the relevant factors such as age, osteoporosis, sliding of lag screw, TAD, fracture stability were analyzed.

Time to union averaged 14.1 weeks in stable fractures and 21.5 weeks in unstable fractures. Acceptable reduction was available in 75 (91.5%) cases. Superior-anterior positioning of the lag screw was only found in 3 (3.4%) cases. Average sliding of the lag screw was 3.9 mm. Mean proximal protrusion of the nail was 4.8 mm, and mean TAD was 25.29 mm. Cutting-out was occurred in 9 (10.8%) cases. Sliding (>10 mm) and TAD (>25 mm) were related significantly to cutting-out (p<0.05). Complications occurred in 26 cases (31.2%), however, there was only one case of cutting-out in reverse obliquity fracture accompanying subtrochanteric component.

Complications for the treatment of peritrochanteric fracture using a gamma nail were not insignificant. To prevent cutting out of lag screw, care must be taken to keep the TAD below 25 mm.