Neurosurgery 98:1040–1050, 2026
This study evaluates long-term clinical outcomes of age-adjusted sagittal alignment correction in adult spinal deformity (ASD) surgery by integrating PI–LL, pelvic tilt, T1 pelvic angle, and SVA. Using hierarchical cluster analysis on 386 patients with long-segment fusion, three postoperative alignment patterns emerged—undercorrected, matched, and overcorrected—correlated with differing radiographic trajectories and complication rates.
Patients in the matched-correction cluster achieved the best balance of clinical improvement (ODI and SRS-22r) and minimized proximal junctional kyphosis/failure, while overcorrection increased mechanical complications despite stronger radiographic correction. The results support a multi-parameter, age-adjusted strategy and propose cluster-derived offset ranges as practical surgical benchmarks.
Aim Evaluate long-term benefits of age-adjusted sagittal alignment in adult spinal deformity surgery by integrating PI–LL, PT, TPA, and SVA using hierarchical cluster analysis.
Cohort Retrospective review of 386 ASD patients undergoing ≥5-level fusion including sacrum/pelvis, with minimum 2-year follow-up (mean follow-up 36.6 months).
Targeting method Postoperative offsets (target − current) for PI–LL, PT, TPA, and SVA were computed using published age-adjusted formulas from 6-week radiographs (or immediate postop if early PJK).
Clustering outcome Patients stratified into 3 clusters (A: 72, B: 211, C: 103) with cluster A undercorrected, cluster B balanced/matched, and cluster C overcorrected trends across all parameters.
Mechanical complications PJK/PJF rates differed by cluster, highest in cluster C (37.9%) vs cluster B (27.5%) and cluster A (20.9%) (P = .046).
Patient-reported outcomes At final follow-up, cluster B had significantly better ODI and SRS-22r outcomes than clusters A and C.
Parameter relationships Offsets showed strong correlations: PI–LL with PT (r = 0.77) and PI–LL with TPA (r = 0.79); weaker with SVA (r = 0.43).
Practical implication A balanced multi-parameter alignment profile (cluster B) best optimized outcomes while reducing complications, supporting integrating multiple sagittal targets rather than relying on a single parameter.
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