Purpose: Our study aimed to confirm the correlation between the Cranial Sagittal Vertical Axis (CrSVA) and patient-reported outcomes and to compare clinical correlation between CrSVA and C7 SVA in adult spinal deformity (ASD) patients.
Methods: 108 consecutive ASD patients were evaluated using the EOS® 2D/3D radio-imaging device. A vertical plumb line from the cranial center was utilized to measure the distance to the posterior corner of S1 (CrSVA-S), and to the centers of the hip (CrSVA-H), the knee (CrSVA-K), and ankle (CrSVA-A), as well as measuring the standard C7 SVA. We analyzed the correlation between each CrSVA parameter with the Oswestry Disability Index (ODI) and Scoliosis Research Society form (SRS-22r).
Results: All 4 CrSVA measures demonstrated strong correlation with the ODI and SRS-22r total score and the pain, self-image, and function subscores. Of note, CrSVA-A (Global SVA) also strongly correlated with the SRS satisfaction subscore. Univariate linear regression showed similar results. The strongest predictor of outcomes was CrSVA, not C7 SVA; (CrSVA-H for ODI, SRS total score, and the pain, self-image, and function subscores; and Global SVA for satisfaction and mental health subscores).
Conclusions: The clinical correlation effect of outcome scores to the CrSVA measures is validated. Global SVA has an especially strong correlation with ODI and all the SRS subscores. Our study confirms that CrSVA is a stronger predictor of preoperative clinical outcomes than the C7 SVA in adult deformity patients.
Keywords: Adult spinal deformity; C7 sagittal vertical axis; Cranial sagittal vertical axis; Health-related quality-of-life.