A Retrospective Comparison of Cephalomedullary Nail Fixation of Intertrochanteric Femur Fractures Treated With Locked Versus Backed-off Set Screws.

Introduction: Excessive lag screw sliding after cephalomedullary nail fixation of intertrochanteric fractures can be problematic. Set screws are typically inserted to engage the lag screw and backed off to allow for sliding. The purpose of this study was to determine whether statically locking set screws affected lag screw sliding or cutout.

Methods: A retrospective review was done at a single level 1 trauma center. Patients treated with locked versus backed-off set screws were compared in terms of lag screw sliding, loss of reduction, and lag screw cutout.

Results: There were 186 patients included. The median age was 67.0 years (IQR 57.0 to 79.0 years) and 56.4% (n = 105) were male. Locked versus backed-off set screws were used in 23.7% (n = 44) and 76.3% (n = 142). The locked set screw group, compared with the backed-off set screw group, had a longer follow-up (4.0 vs. 3.0 months, P = 0.02), had a greater median tip-apex distance (21.3 vs. 19.0, P = 0.04), and did not differ in age, sex, acute varus displacement (vertical displacement of greater trochanter above the femoral head on injury radiographs), postoperative neck-shaft angle, or calcar gapping. The locked set screw group, compared with the backed-off set screw group, had less lag screw sliding (2.3 vs. 3.6 mm, P = 0.02) and no difference in lag screw sliding ≥10 mm (6.7% vs. 7.8%, P = 1.0), loss of reduction ≥10 mm (6.8% vs. 9.2%, P = 0.7), or cutout (0.0% vs. 1.4%, P = 1.0). Patients who had ≥10 mm of lag screw sliding were older (76.5 vs. 66.0, P = 0.04), more likely to have acute varus displacement (50.0% vs. 23.2%, P = 0.04), and had more varus postoperative neck-shaft angles (129° vs. 132°, P = 0.03).

Conclusion: Locked set screws, compared with backed-off set screws, resulted in a median of 1.3 mm less of lag screw sliding and did not affect the rate of lag screw sliding ≥10 mm, loss of reduction, or cutout.

Level Of Evidence: Level III, retrospective comparison.