Targeted Fully-Threaded Screw Augmentation with the Femoral Neck System Reduces Neck Shortening and Posterior Tilt, Leading to Improved Function in Geriatric Garden I-II Femoral Neck Fractures: A Retrospective Comparative Study.

BACKGROUND: This study aimed to evaluate whether targeted fully-threaded screw augmentation with the femoral neck system (FNS) reduces femoral neck shortening and posterior tilt, thereby improving functional outcomes in geriatric patients with Garden types I and II femoral neck fractures. METHODS: We retrospectively reviewed the clinical and radiographic data of geriatric patients (> 60 years) with Garden type I or II femoral neck fractures who underwent FNS fixation and completed a 6-month follow-up. Of these, 32 patients received targeted fully-threaded screw augmentation with FNS (TFS-FNS group), while 24 underwent single FNS fixation (single FNS group). The 2 groups were compared in terms of femoral neck shortening, posterior or anterior tilt, bone union rate, Harris Hip Score (HHS), and complications, including those potentially associated with fully-threaded screw fixation. Additionally, we analyzed factors associated with functional outcomes. A subgroup analysis was performed to assess whether targeted fully-threaded screw augmentation could reduce re-shortening and recurrent posterior tilt following closed reduction. RESULTS: There were no significant differences in demographic or clinical characteristics except for a higher prevalence of Pauwels type III fractures in the TFS-FNS group. All shortening-related outcomes were significantly lower in the TFS-FNS group (vertical: 1.46 ± 1.49 mm; horizontal: 0.87 ± 1.14 mm; total: 1.88 ± 1.70 mm) than in the single FNS group (vertical: 4.08 ± 2.83 mm; horizontal: 2.28 ± 2.42 mm; total: 5.31 ± 2.69 mm) (p < 0.001). The TFS-FNS group also showed reduced posterior or anterior tilt progression (1.49° ± 1.77° vs. 8.90° ± 8.82°; p < 0.001) and superior HHS (88.97 ± 8.13 vs. 79.04 ± 11.71; p = 0.001). Bone union rates and operation times were comparable, with no complications related to fully-threaded screw fixation in the TFS-FNS group. In multivariate analysis, age (p = 0.022) and femoral neck shortening (p = 0.048) were significantly associated with HHS. Subgroup analysis of patients who underwent closed reduction showed that the TFS-FNS group had significantly less re-shortening and recurrent posterior or anterior tilt (p < 0.001 and p = 0.002, respectively). CONCLUSIONS: Targeted fully-threaded screw augmentation combined with the FNS effectively reduced femoral neck shortening and posterior or anterior tilt in geriatric Garden types I and II femoral neck fractures, leading to improved functional outcomes without increasing complication rates.