Superior reduction quality without improved outcomes: open versus closed reduction for displaced femoral neck fractures in adults under 60 years

The optimal reduction strategy for displaced femoral neck fractures (DFNFs) in non-elderly adults remains controversial. Although open reduction may improve radiographic alignment, its impact on outcomes remains unclear. Adults aged < 60 years with DFNFs who were treated with internal fixation between 2017 and 2023 were retrospectively reviewed. Patients were categorized into closed and open reduction groups. Reduction quality was assessed using the Garden alignment index and the Haidukewych reduction criteria. Multivariate analyses were performed for the overall cohort and patients with Pauwels type III fractures. Outcomes included non-union, osteonecrosis, femoral neck shortening, and major reoperations. In total, 98 patients were included, among whom 83 and 15 underwent closed and open reduction, respectively. Although open reduction achieved a higher rate of excellent reduction (53.3% vs. 16.9%, p = 0.012), it was not associated with lower rates of non-union or osteonecrosis. In the overall cohort, age was associated with non-union (odds ratio [OR], 1.09; p = 0.024), whereas poorer reduction quality was associated with major reoperation (fair: OR 7.03, p = 0.012; poor: OR 47.6, p = 0.007). In patients with Pauwels type III fractures, poorer reduction quality predicted conversion to arthroplasty (fair: OR 9.84, p = 0.014), and age was associated with non-union and osteonecrosis. Femoral neck shortening of > 10 mm at 3 months was associated with age and open reduction, whereas at 12 months, age and intraoperative blood loss remained significant predictors. Open reduction achieved a higher rate of excellent reduction but did not reduce complication rates compared with closed reduction. Fracture severity, patient age, and reduction quality remained the principal determinants of outcome, supporting a fracture morphology-guided fixation strategy and realistic patient counseling.