Cephalomedullary helical blade is independently associated with less collapse in intertrochanteric femur fractures than lag screws.

ABSTRACT

OBJECTIVES: Excessive fracture site collapse and shortening in intertrochanteric femur fractures alter hip biomechanics and patient outcomes. The purpose of the study was to compare extent of collapse in cephalomedullary nails with blades or lag screws. We hypothesized that there would be no difference in collapse between helical blades and lag screws. DESIGN: Retrospective cohort study. SETTING: Single U.S. Level I Trauma Center. PATIENTS 171 consecutive patients treated with cephalomedullary nails with either lag screw or blade for AO/OTA 31A1-3 proximal femur fractures and minimum 3-month follow-up. INTERVENTION Lag screw or helical blade in a cephalomedullary nail. OUTCOME MEASURES: The primary outcome was fracture site collapse at 3 months. RESULTS: There was a significantly higher proportion of reverse-oblique and transverse intertrochanteric femur fractures (31-A3) in the lag screw group (15/42 vs 25/129). A3 patterns were associated with more collapse. There was significantly less collapse in the blade group (median 4.7 mm, inter-quartile range 2.5-7.8 mm) than the screw group (median 8.4 mmm, inter-quartile range 3.7-11.2 mm, p 0.006). Median collapse was no different between blades and screws when comparing stable and unstable patterns. However, blades were independently associated with 2.5 mm less collapse (95%CI - 4.2, - 0.72 mm, p 0.006) and lower likelihood of excessive collapse (> 10 mm at 3 months, OR 0.3, 95% CI 0.13-0.74, p 0.007), regardless of fracture pattern. CONCLUSIONS: Helical blades are independently associated with significantly less collapse than lag screws in intertrochanteric proximal femur fractures, after adjusting for unstable fracture patterns. In fracture patterns at risk for collapse, surgeons can consider use of a helical blade due to its favorable sliding properties compared to screws.