Early outcomes of the synthes femoral neck system for valgus-impacted femoral neck fractures: a multicenter retrospective study.

Abstract

Nondisplaced and valgus-impacted femoral neck fractures have traditionally been treated with screw fixation, but reoperation rates remain high. This study reports clinical outcomes following internal fixation of low-energy femoral neck fractures (AO/OTA 31B1.1 and 31B1.2) using a new, fixed-angle sliding device. This was a multi-institutional retrospective review at four academic Level I Trauma Centers, one Level II Trauma Center, and one Level III Trauma Center. Patients with AO/OTA 31B1.1 and 31B1.2 fractures who underwent internal fixation using the Femoral Neck System ("FNS," DePuy Synthes, West Chester, PA) and had follow-up to radiographic union or reoperation (mean 11.9 months) were included. Fractures with ≥ 20° of posterior tilt were included but distinguished as the "posterolateral" group. Primary outcome was reoperation rate. Secondary outcomes included fixation failure, infection, nonunion, and mortality rates at 3 and 6 months. A total of 116 patients met inclusion criteria including 109 "stable" fractures with < 20° of posterior tilt, and seven valgus-impacted fractures with ≥ 20° of posterior tilt ("posterolateral"). All posterolateral fractures underwent a reduction maneuver to reduce posterior tilt prior to fixation. Overall reoperation rate was 10%, including a 5.2% reoperation rate for AVN, with no patients in the posterolateral group requiring reoperation. Nonunion rate was 1.8%, and there was only one case of acute fixation failure (0.9%), which occurred after a repeat fall. Mortality rate was 0.9% at 3 months and 2.2% at 6 months. Surgical fixation of nondisplaced and valgus-impacted femoral neck fractures with a femoral neck-specific, fixed-anglescrew-side plate device appears safe and effective. Reoperation rate remained low in the high-risk posterolateral subgroup when reduction maneuvers were performed. III.