The Parallelogram Effect of Degenerative Structures Around the Apical Vertebra in Patients with Adult Degenerative Scoliosis: The Influence of Asymmetric Degeneration and Diagonal Degeneration on the Severity of Deformity

BACKGROUND This is the first published study assessing the parallelogram effect of degenerative structures around the apical vertebra. We evaluated the effect of degenerative structures around the apical vertebra and spinopelvic parameters on the severity of ADS. MATERIAL AND METHODS We retrospectively reviewed data on 144 patients with ADS. The coronal (coronal Cobb angle, CA) and sagittal (thoracic kyphosis, TK; sagittal vertical axis, SVA; pelvic incidence, PI; lumbar lordosis, LL; sacral slope, SS; pelvic tilt, PT) parameters, lumbar multifidus muscle atrophy (LMA), and facet joint osteoarthritis (FJOA) were evaluated. Multiple linear regression was used to assess the correlations. RESULTS LL and PT were negatively correlated with CA (P