How the Assessment of Pelvic Tilt, Pelvic Incidence/Lumbar Lordosis Mismatch and Sagittal Vertical Axis Predicts Disability in Adult Spinal Deformity: A Prospective Analysis

Justin S. Smith, MD, PhD1, Christopher Ames, MD1, Frank Schwab, MD1, Shay Bess, MD1, Benjamin Blondel, MD1, Richard Hostin, MD1, Oheneba Boachie Adjei, MD1, Douglas Burton, MD1, Behrooz Akbarnia, MD1, Gregory Mundis, MD1, Khaled Kebaish, MD1, Robert Hart, MD1, Virginie Lafage, PhD1, Christopher Shaffrey, MD1

1Charlottesville, VA United States

Keywords: scoliosis, spinal fusion, spine surgery, pain, thoracic spine

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     Spino-pelvic parameters provide a more complete assessment of sagittal spinal malalignment (SSM) than sagittal vertical axis (SVA) alone. Little data has correlated spino-pelvic parameters with disability.
     The purpose was to evaluate correlations between sagittal spino-pelvic parameters and health related quality of life (HRQOL) scores.
     Inclusion criteria: age<18 and ASD (scoliosis<20°, SVA<5cm, pelvic tilt PT<25°, or thoracic kyphosis<60°).492 consecutive ASD patients (mean age=51.9, SD 16.8) were enrolled. 
     Demographic, radiographic, and HRQOL data were obtained from patients consecutively enrolled into a multi-center, prospective study evaluating operative (OP) vs. nonoperative (NON) treatment for adult spinal deformity (ASD). HRQOL questionnaires: Oswestry Disability Index (ODI), Scoliosis Research Society Questionnaire (SRS-22r). Radiographic parameters demonstrating highest correlation with HRQOL values were evaluated to determine a disability threshold of ODI?40.
     Patients treated OP (n=178) were older (55 vs. 50.1, p<0.05), had greater SVA (5.5 vs. 1.7cm, p<0.05), greater PT (22° vs. 11°, p<0.05) and greater pelvic incidence/ lumbar lordosis mismatch (PI-LL; 12.2 vs. 4.3; p<0.05) than NON (n=314). OP demonstrated greater disability on all HRQOL measures compared to NON (ODI =41.4 vs. 23.9, p<0.05; SRS total=2.9 vs. 3.5, p<0.05). Pearson analysis demonstrated PT, SVA, and PI-LL correlated most strongly with disability for both OP and NON patients (p<0.001). Linear regression models demonstrated threshold radiographic spino-pelvic parameters for ODI?40 included: PT?22° (r=0.38), SVA ?46 mm (r=0.47), PI-LL?11 (r=0.45).
     This is a prospective study.
     Prospective analysis of ASD patients demonstrated PT and PI-LL, combined with SVA, predict patient disability and provide a guide for patient assessment.
     Threshold values for severe disability included: PT?22°, SVA ?46mm, and PI-LL?11°.


Project Roles:

J. Smith (), C. Ames (), F. Schwab (), S. Bess (), B. Blondel (), R. Hostin (), O. Adjei (), D. Burton (), B. Akbarnia (), G. Mundis (), K. Kebaish (), R. Hart (), V. Lafage (), C. Shaffrey ()