Clinical outcomes of femoral neck fractures in nongeriatric patients: a comparative analysis of parallel screws, alpha fixation and femoral neck system

Abstract

Purpose: Femoral neck fractures in nongeriatric patients pose a significant clinical challenge due to the high clinical failure rate. To address this, Alpha fixation and the Femoral Neck System (FNS) were developed but seldom been compared head-to-head. The purpose of this study was to compare the clinical prognosis of these two methods with traditional parallel screws. Methods: This retrospective cohort study included 341 patients aged 18–65 years, treated between June 2020 and June 2023. Patients were grouped by fixation strategies: (1) parallel screws (n = 206), (2) Alpha fixation (n = 73), and (3) FNS (n = 62). Fixation failure (nonunion, severe femoral neck shortening, varus collapse) was compared as primary clinical outcome using univariate and multivariate analyses. Secondary outcomes included avascular necrosis and reoperation rates. Analyses were stratified by Pauwels classification. Results: Fixation failure rates were highest with parallel screws (21.4%), intermediate with FNS (12.9%), and lowest with Alpha fixation (9.6%). Multivariate analysis showed significantly lower fixation failure with Alpha fixation compared to parallel screws (adjusted OR = 0.29, 95% CI: 0.10–0.73, p = 0.014). Alpha fixation significantly reduced femoral neck shortening (p = 0.017), whereas FNS significantly reduced varus collapse (p = 0.013). In Pauwels type III fractures, Alpha fixation and FNS both significantly reduced fixation failure rates compared to parallel screws; no difference was found in Pauwels types I–II. Conclusions: Alpha fixation and FNS significantly outperformed parallel screws in reducing fixation failure in vertical femoral neck fractures among nongeriatric patients. Alpha fixation showed advantages in limiting femoral neck shortening, whereas FNS more effectively prevented varus collapse. For stable fractures, conventional parallel screws remain a reasonable choice.