Is the Cranial Sagittal Vertical Axis (Cr-SVA) a Better Midterm Predictor of Clinical Results Than C7-SVA in Adult Patients Operated on Spinal Deformity After a Minimum 2-Year Follow-Up?

Study Design: This is nonconcurrent prospective study approved by the Institutional Research Ethics Committee.
Objective: The purpose of this study is to determine if the cranial sagittal vertical axis (Cr-SVA) measured in full spine standing radiographs is a better predictor of clinical results than the C7 sagittal vertical axis (C7-SVA) in adult patients operated on spinal deformity with a minimum 2-year follow-up after surgery.
Summary of Background Data: The Cr-SVA has recently been described as a better predictor of health-related quality of life outcomes than the C7-SVA for patients with adult spinal deformity (ASD) before undergoing surgery. This has not been confirmed in patients after ASD surgery.
Methods: Inclusion criteria were age at surgery more than 25 years and a minimum 2-year follow-up after a ≥5 level fusion for ASD. Full-length standing lateral radiographs (including nasion-inion line, spine, and femoral heads) and Scoliosis Research Society 22 Questionnaire and SF36 questionnaires were available for every patient at the final follow-up. The distance from the Cr-SVA to the posterior corner of S1 (Cr-SVA-S) and to the centers of the hip (Cr-SVA-H) was measured and also the C7-SVA, lumbar lordosis, pelvic incidence, pelvic tilt, and PI-LL.
Results: Sixty-five patients (58 female individuals) operated on ASD in a single institution were included. Age at surgery was 61 years (26-67). The mean follow-up was 53 months (24-120). Spearman rank-order test showed several significant correlations. After multivariable analysis, only Cr-SVA-S and age persisted as predictors for Scoliosis Research Society (SRS) image scores, Cr-SVA-H for SRS satisfaction, Cr-SVA-H and age for SRS total scores, Cr-SVA-H and age for SF36 Physical Function, Cr-SVA-S for SF36 Role Physical, Cr-SVA-H for SF36 Bodily Pain, and Cr-SVA-H for SF36 Role Emotional.
Conclusions: The Cr-SVA measured in full spine standing radiographs seems to be a better predictor of health-related quality of life outcomes than the C7-SVA for adults operated on spinal deformity >2 years after surgery.
Competing Interests: The authors declare no conflict of interest.
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