Spinopelvic Parameters, Degree of Correction, and Proximal Junctional Complications After Adult Spinal Deformity...

Proximal junctional kyphosis (PJK) is a frequent postoperative complication following adult spinal deformity (ASD) surgery, whereas proximal junctional failure (PJF) is a less common but clinically more severe complication. Spinopelvic radiographic parameters have been associated with the development of these complications, yet existing studies have reported inconsistent results. This study aimed to investigate the association between spinopelvic parameters and proximal junctional complications (PJK/PJF), including analysis based on age-adjusted pelvic incidence (PI)-lumbar lordosis (LL) mismatch categories.

This review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) 2020 guidelines. PubMed, Cochrane Library, and Embase were comprehensively searched from inception through March 2025. Adults (>18 years) who underwent surgery for ASD or long-segment (≥4 levels) spinal fusion were included. Studies were independently selected by 2 reviewers based on preset criteria. Random-effects model was used to calculate mean differences/standardized mean differences for continuous variables and odds ratios (ORs) for categorical outcomes.

A total of 47 retrospective studies were included in the meta-analysis. Preoperatively, the PJK group had lower LL and sacral slope (SS) but had higher pelvic tilt (PT), T1PA, and C7-sagittal vertical axis than the non-PJK group. Postoperatively, the PJK group showed significantly lower PI-LL mismatch values and SS and higher PT, thoracic kyphosis, thoracolumbar kyphosis, and T1 pelvic angle. When stratified by the age-adjusted PI-LL formula, overcorrection was associated with significantly higher odds of PJK (OR, 2.67; 95% confidence interval [CI], 1.61-4.42), whereas no significant association was observed for PJF. Using age-specific thresholds, overcorrection was significantly associated with higher odds of PJF (OR, 1.67; 95% CI, 1.10-2.52).

Preoperative sagittal imbalance and postoperative spinopelvic differences were associated with proximal junctional complications, whereas associations for PJF were more limited. Age-adjusted overcorrection showed outcome-specific associations with proximal junctional complications, suggesting that age-tailored alignment may be clinically relevant. Given the retrospective aggregate evidence and limited age-adjusted data, future prospective studies with standardized radiographic timing and separate outcome assessment for PJK and PJF are needed to validate these findings.