Comparison of Femoral Neck System Fixation Outcomes in Nondisplaced Femoral Neck Fractures: A Multicenter Retrospective Study of Patients Aged Below and Above 75 Years

Purpose The use of fixation and arthroplasty in treating elderly patients with nondisplaced femoral neck fracture (FNF) remains controversial. The femoral neck system (FNS) is known to have relatively stronger axial and rotational stability compared with cancellous screw fixation. This study aimed to evaluate how effective internal fixation using a FNS is for non-displaced FNF in elderly patients. Methods All patients with nondisplaced (Garden I and II) FNF between July 2019 and November 2023 were eligible for osteosynthesis surgery at three institutions. Ninety-five patients (50 under 75 years of age and 45 over 75 years of age) who were treated with FNS with a follow-up period of more than 1 year were included. Clinical data (age, sex, direction, body mass index, injury mechanism, bone mineral density (BMD), and time to operation) were extracted from patient records. Institutional imaging software was used for radiographic analysis to evaluate surgical site complications at 1 year. Multivariate logistic regression analysis was performed to identify independent risk factors for reoperation. Results The mean age of the younger group was 61.0 years, whereas that of the elderly group was 81.2 years. No significant differences were observed between the two groups except for BMD and time to operation. Three reoperations were observed in the younger group (6%), and four cases were observed in the elderly group (8.9%) (p = 0.894), and no significant difference in other surgical complications was observed between the two groups. BMD was identified as an independent risk factor for reoperation. Conclusion FNS may be used as an alternative to elderly and younger patients with nondisplaced FNFs. However, the reoperation rate may increase in severe osteoporosis patients with very low hip BMD.