To analyze the cause of excessive sliding of a compression hip screw for the treatment of an intertrochanteric fracture in elderly patients.

109 intertrochanteric fractures stabilized with a compression hip screw from January 2000 to December 2006 were analyzed. The lag screws that had slid for more than 15 mm were defined as excessive. The length and incidence of compression hip screw sliding, which were compared with the fracture type (AO classification), tip-apex distance (TAD), position of the lag screw in the femoral head, use of trochanteric stabilizing plate and displacement of lesser trochanter were analyzed.

Fourteen out of 109 cases (13%) had slid more than 15 mm. In the AO classification, 3 out of 47 (6.4%)A1 fractures, 10 out of 59 (17%) A2 fractures, and 1 out of 3(33%) A3 fractures slid excessively. In patients with a displaced lesser trochanter fragment more than 10 mm, there were 9 cases (9/10) that slid excessively. Most of the lag screws (84 out of 109) were placed in zone 5, and 9(11%) of them had slid excessively. Five were placed in zone 2 and 4 (80%) had slid excessively. Five of the 18 with a tip-apex distance of 25 mm or more had slid excessively.

In A2 fractures, the size and displacement of the lesser trochanter fragment appears to be an important factor for excessive sliding. In addition, the position of the lag screw and TAD (Tip-Apex Distance) are factors for excessive sliding.