Preoperative posterior tilt increases the risk of later conversion to arthroplasty after osteosynthesis for femoral neck fracture

Abstract Background Femoral neck fractures (FNF) are one of the most common injuries in the elderly. Treatment is either internal fixation or primary arthroplasty. The main aim of this study was to assess the risk factors associated with fixation failure leading to further arthroplasty in FNFs treated with cannulated screws. Patients and methods Data on internal fixations of FNFs performed at Turku University hospital between 1 January 2012 and 31 December 2017 were collected retrospectively from the patient database. Radiographical measurements were performed for preoperative displacement and posterior tilt, postoperative displacement, reduction quality and implant shaft angle. Results Altogether 301 cases were included in the study. The overall reoperation rate was 25% and conversion to arthroplasty was performed in 16% of cases. In the multiple variant analysis, adjusted for age and sex, non-displaced fractures with a 0–20° preoperative posterior tilt had a significantly lower risk of later conversion to arthroplasty than did non-displaced fractures with a ≤0° or ≥20° posterior tilt (OR 4.0, 95% Cl 1.8–8.6, p=0.0005) and displaced fractures (OR 7.2, 95% CI 3.0–17.4, p Conclusion Displaced fractures and fractures with a preoperative posterior tilt of 20° or