Predictive value of Hounsfield units and vertebral bone quality on cage subsidence in oblique lateral interbody fusion with bilateral posterior fixation.

Abstract

Cage subsidence (CS) is a significant complication following oblique lateral interbody fusion combined with bilateral pedicle screw fixation (OLIF-BPSF) in patients with spinal degenerative diseases (SDDs). Identifying reliable predictors of CS is crucial for optimizing surgical outcomes. This retrospective cohort study included 314 SDD patients who underwent OLIF-BPSF between July 2019 and July 2023. Preoperative Hounsfield unit (HU) values and vertebral bone quality (VBQ) scores were measured. Statistical analyses included correlation matrices, Kaplan-Meier survival analysis, Cox proportional hazards models, restricted cubic splines, and receiver operating characteristic (ROC) curve analysis. Sensitivity analyses were performed to ensure robustness. CS occurred in 13.38% of patients. Lower global (HR: 0.97, 95% CI: 0.97-0.99) and segmental (HR: 0.97, 95% CI: 0.95-0.98) HU values were significantly associated with higher CS incidence, whereas higher global (HR: 1.67, 95% CI: 1.29-2.16) and segmental (HR: 1.68, 95% CI: 1.30-2.17) VBQ scores were also significantly associated with increased CS risk. A nonlinear relationship was observed between the VBQ score and CS, with CS incidence significantly increasing when the global VBQ score was ≥ 2.67 or the segmental VBQ score was ≥ 2.49. ROC analysis demonstrated good predictive performance for HU values and VBQ scores, with segmental HU values showing superior incremental predictive value (AUC: 0.82). The findings remained consistent across various sensitivity analyses. HU values and VBQ scores independently predict CS in SDD patients undergoing OLIF-BPSF. Incorporating these metrics into preoperative assessments may enhance risk stratification and guide personalized surgical planning.