Accuracy of Lag Screw Placement for the Dynamic Hip Screw and the Cephalomedullary Nail

Abstract

The outcome of peritrochanteric fracture fixation is dependent on lag screw placement in the femoral head. The dynamic hip screw technique permits initial, independent lag screw placement, while the cephalomedullary nail dictates its positioning. The objective of this study was to compare the accuracy of lag screw placement for both implant types. A retrospective review of 200 consecutive patients with peritrochanteric fractures stabilized with a dynamic hip screw or cephalomedullary nail was performed. Postoperative biplanar radiographs were used to determine the lag screw tip-apex distance and femoral head zone placement. The study inclusion criteria were met by 137 patients (66 dynamic hip screw; 71 cephalomedullary nail). The patients included 56% women and 44% men with an average age of 73 years. The tip-apex distance and femoral head zone placement demonstrated no statistically significant difference between the 2 implant groups. The lag screw of a cephalomedullary nail was 3.25 times more likely placed in the antero-center zone compared to the dynamic hip screw, and this was statistically significant when compared to other zones. There was a trend toward a more favorable tip-apex distance in women for both implants. The accurate placement of the lag screw can be routinely achieved for both dynamic hip screw and cephalomedullary nail implants, and therefore should not a factor in the selection of these implants for adequate peritrochanteric fracture stabilization. These results represent the immediate postoperative setting, and a follow-up is warranted to establish their long-term clinical relevance.