Predictors of Age-Adjusted Pelvic Tilt Correction After Long-Segment Adult Spinal Deformity Correction.

BACKGROUND CONTEXT: Pelvic tilt (PT) reflects sagittal alignment compensation in adult spinal deformity and is associated with postoperative outcomes. Achievement of age-adjusted PT after long segment fusion demonstrates substantial improvements in health-related quality of life and a reduction of complications. However, many patients fail to normalize PT and predictors remain incompletely defined.

PURPOSE: This study aims to identify preoperative and surgical predictors of PT correction using age-adjusted thresholds in patients undergoing long-segment thoracolumbar fusion with pelvic fixation.

STUDY

DESIGN

Retrospective cohort study.

PATIENT SAMPLE: Adult spinal deformity (ASD) patients undergoing long-segment thoracolumbar fusion with pelvic fixation with preoperative PT above age-adjusted targets (n=129).

OUTCOME MEASURES: Primary outcome was achievement of age-adjusted PT at 12 months postoperative. Radiographic parameters included pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), T1 pelvic angle (T1PA), and proportional correction measures normalized to PI.

METHODS

Patients were dichotomized based on PT normalization at 12 months. Extent of spinopelvic correction and deviation from ideal was calculated and normalized by PI. Mixed-effects multivariable logistic regression controlled for confounding variables. Univariate area under curve (AUC) assessed predictive performance.

RESULTS

Patients who normalized PT at 12 months had lower baseline PI, PT, SS, and LL. When normalized to PI, these associations became stronger. T1PA deviation ratio, ΔLL/PI, and PI were identified as independent predictors of PT normalization. T1PA had the highest discriminatory ability (AUC=0.803), while PI was the strongest negative predictor (AUC=0.745).

CONCLUSION

PT correction depends on both baseline alignment and extent of surgical correction. Greater correction of LL and T1PA proportional to PI, were independently associated with PT normalization.