Acetabular morphology, centre-edge angle and cognitive impairment as predictors of dislocation and mortality after hip hemiarthroplasty.

BACKGROUND: Dislocation after hip hemiarthroplasty (HHA) for intracapsular femoral neck fractures remains a serious complication associated with functional deterioration and increased mortality. This study aimed to evaluate the role of acetabular morphology and cognitive impairment as predictors of postoperative dislocation and mortality in patients treated with cemented bipolar HHA.

METHODS: A retrospective analytical cohort of 160 patients was analysed. Preoperative acetabular parameters, including acetabular depth and centre-edge angle (CEA), were measured on standardised anteroposterior pelvic radiographs, and cognitive status was evaluated using the GDS and FRAIL scales.

RESULTS: Multivariable logistic regression incorporating surgical approach identified acetabular depth <20 mm (OR 16.42; 95% CI, 4.88-55.27; p < 0.001) and CEA <40° (OR 3.27; 95% CI, 1.12-9.56; p = 0.031) as independent predictors of postoperative dislocation, while surgical approach did not remain independently associated after adjustment. Dislocation was associated with increased mortality at 3 and 12 months, supporting its interpretation as a marker of global vulnerability in this frail population. The final model demonstrated good calibration and acceptable discriminative capacity (AUC 0.794).

CONCLUSIONS: Acetabular depth <20 mm and CEA <40° independently predict postoperative instability after cemented bipolar HHA, and reduced depth correlates with increased mortality, reinforcing its value as an anatomical and functional marker. Integrating radiographic acetabular evaluation with cognitive screening may enhance risk stratification and guide pre-operative planning and postoperative supervision.