The purpose of this study was to analyze the factors affecting fixation failures of intertrochanteric fractures of the femur treated by dynamic compression hip screw in elderly patients.

Between March 1999 and February 2005, we evaluated 164 cases of intertrochanteric fractures of the femur treated by dynamic compression hip screw. The failure group (group 1) contained 14 cases, and the control group (group 2) contained 150 cases. We compared the fracture pattern, type of reduction, method of fixation, tip-apex distance, location of screw within head, and presence of lateral trochanteric wall fracture between the two groups. The average patient age was 76.1 years (range 63-92) in group 1 and 75.0 years (range 63-93) in group 2.

The mode of fixation failure in group 1 included 6 cases of nonunion, 5 cases of varus and cutting-out, 2 cases of excessive sliding of lag screw, and 1 case of plate debonding. There was a significant relationship between the fracture pattern, tip-apex distance, position of lag screw (especially the posterior location), and presence of lateral wall fracture when compared against postoperative fixation failure (P<0.05). The use of bone cement augmentation and the central location of lag screw within the head correlated with the avoidance of cutting-out of lag screw through the head. However, there was no relationship between the type of reduction, the use of additional fixation with a screw, or greater trochanter stabilizing plate when compared against fixation failure.

The structural integrity of lateral wall support is thought to be an essential factor in successful treatment of unstable intertrochanteric fractures of the femur. Furthermore, methods such as concentric screw placement in the head, minimal tip-apex distance, and cement augmentation may be useful for preventing cutting-out through obtaining secure purchase of the lag screw in the head.