Association between spinopelvic parameters and clinical outcomes following hip fracture: an observational retrospective study

Background: Femoral neck fractures carry a substantial risk of complications such as varus malalignment, avascular necrosis and the need for reoperation. While traditional prognostic factors have been extensively studied, the relevance of postoperative spinopelvic characteristics after internal fixation remains unclear. This study evaluated whether spinopelvic parameters measured on standardized postoperative radiographs are associated with adverse outcomes. Methods: Ninety-six patients aged 18-60 years who underwent internal fixation for femoral neck fractures were analysed. Demographic variables, fracture characteristics, fixation type and postoperative complications were recorded retrospectively. Sacral slope, pelvic tilt, pelvic incidence and sacral slope difference were measured on lateral lumbosacral radiographs obtained at the 6 month follow-up. Associations with varus deformity, avascular necrosis and reoperation were assessed using univariable and multivariable logistic regression. Results: Sacral slope difference demonstrated consistent associations with all major complications. Patients with higher sacral slope difference had significantly greater rates of varus deformity, avascular necrosis and reoperation. Higher pelvic tilt was associated with avascular necrosis, and higher pelvic incidence was associated with reoperation. Several multivariable analyses met exploratory criteria due to limited events per variable, and these results should be interpreted with caution. Interobserver reliability for all spinopelvic measurements was excellent. Conclusion: Spinopelvic parameters, particularly sacral slope difference, were associated with key complications after internal fixation of femoral neck fractures. These postoperative measurements may help identify patients who could benefit from closer follow-up, although they should not be interpreted as predictive factors. Prospective studies are required to validate these associations and clarify their clinical relevance.