LAUSR

Background Hip fractures represent the most common injury and the main cause of morbidity and mortality among patients 65 years and older. About 20% of all femoral neck fractures (FNFs) are non-displaced or valgus impacted, for which internal fixation with the cannulated screws system (CSS) is indicated. Aims The aim of this study was to identify predictors of early failure of CSS. Methods Patients with non-displaced FNFs (Garden type I and II) treated operatively using the CSS were enrolled. Their characteristics, Pauwels angle, and posterior tilt were assessed and related with outcomes. The primary outcome was fixation failure within 6 months. Results 259 patients were included with a mean age of 81.44 years. Most patients were female with ASA 3. The majority of fractures were classified as Garden I and Pauwels I. On average, Pauwels angle was 27°, while posterior tilt was 12°. A linear correlation between Pauwels angle and posterior tilt was found; the failure rate was 9.7%. Using the adjusted Cox competing risk regression analysis, posterior tilt was found to be independently associated with failure rate (sub-distribution hazard ratio or SHR 1.14 [95% CI 1.05–1.24], p  = 0.0020). A posterior tilt greater than 18° resulted predictive of failure. The 1-year mortality rate was 12%. Conclusions Non-displaced Garden type II fractures, Pauwels type II or III fractures, and a posterior tilt greater than 18° represent radiographic predictors of CSS early failure in the elderly. Level of evidence Level IV, retrospective cohort study.