BACKGROUND: The comparative durability of single- versus multi-level fusion remains debated. METHODS: We prospectively followed 412 patients for a median of 5.2 years. RESULTS: Reoperation rates were 8.1% (single-level) vs 14.6% (multi-level); patient-reported outcomes converged by 24 months.

A retrospective review of 287 adult spinal deformity corrections identified low bone density, high pelvic incidence–lumbar lordosis mismatch, and upper-instrumented-vertebra selection as independent predictors of proximal junctional kyphosis at two years.

A gradient-boosted model trained on 6,400 posterior cervical decompressions achieved an AUC of 0.81 for 90-day readmission, outperforming the ACS-NSQIP calculator. Frailty index and operative duration were the dominant features.