Radiographical Spinopelvic Parameters and Disability in the Setting of Adult Spinal Deformity A Prospective Multicenter Analysis

Study Design. Prospective multicenter study evaluating operative (OP) versus nonoperative (NONOP) treatment for adult spinal deformity (ASD). Objective. Evaluate correlations between spinopelvic parameters and health- related quality of life (HRQOL) scores in patients with ASD. Summary of Background Data. Sagittal spinal deformity is commonly defi ned by an increased sagittal vertical axis (SVA); however, SVA alone may underestimate the severity of the deformity. Spinopelvic parameters provide a more complete assessment of the sagittal plane but only limited data are available that correlate spinopelvic parameters with disability. Methods. Baseline demographic, radiographical, and HRQOL data were obtained for all patients enrolled in a multicenter consecutive database. Inclusion criteria were: age more than 18 years and radiographical diagnosis of ASD. Radiographical evaluation was conducted on the frontal and lateral planes and HRQOL questionnaires (Oswestry Disability Index [ODI], Scoliosis Research Society-22r and Short Form [SF]-12) were completed. Radiographical parameters demonstrating highest correlation with HRQOL values were evaluated to determine thresholds predictive of ODI more than 40. Results. Four hundred ninety-two consecutive patients with ASD (mean age, 51.9 yr) were enrolled. Patients from the OP group (n = 178) were older (55 vs. 50.1 yr, P < 0.05), had greater SVA (5.5 vs. 1.7 cm, P < 0.05), greater pelvic tilt (PT; 22 degrees vs. 11 degrees, P < 0.05), and greater pelvic incidence/lumbar lordosis PI/LL mismatch (PI-LL; 12.2 vs. 4.3; P < 0.05) than NONOP group (n = 314). OP group demonstrated greater disability on all HRQOL measures compared with NONOP group (ODI = 41.4 vs. 23.9, P < 0.05; Scoliosis Research Society score total = 2.9 vs. 3.5, P < 0.05). Pearson analysis demonstrated that among all parameters, PT, SVA, and PILL correlated most strongly with disability for both OP and NONOP groups (P < 0.001). Linear regression models demonstrated threshold radiographical spinopelvic parameters for ODI more than 40 to be: PT 22 degrees or more (r = 0.38), SVA 47 mm or more (r = 0.47), PI -LL 11 degrees or more (r = 0.45). Conclusion. ASD is a disabling condition. Prospective analysis of consecutively enrolled patients with ASD demonstrated that PT and PI-LL combined with SVA can predict patient disability and provide a guide for patient assessment for appropriate therapeutic decision making. Threshold values for severe disability (ODI > 40) included: PT 22 degrees or more, SVA 47 mm or more, and PI -LL 11 degrees or more.