Ethnic Variations in Radiographic Parameters and SRS-22 Scores in Adult Spinal Deformity: A Comparison Between North American and Japanese Patients Above 50 Years of Age With Minimum 2-Year Follow-up.

STUDY DESIGN: Retrospective review of North American and Japanese adult spinal deformity (ASD) database. OBJECTIVE: To investigate the ethnical differences in radiographic parameters and Scoliosis Research Society (SRS)-22 between North American and Japanese ASD. SUMMARY OF BACKGROUND DATA: Previous comparison study between North American and Japanese ASD patients has revealed Japanese patients had marked pelvic tilt deformity and had lower Oswestry Disability Index scores corresponding to established thresholds of radiographic deformity. However, the subjects of the previous study included relatively younger ASD patients (above 18 y) of idiopathic origin. MATERIALS AND METHODS: Total 282 ASD patients older than 50 years, 211 patients from North America (United States) and 71 patients from Japan (JP), with minimum 2-year follow-up postoperatively were included in the study. Radiologic parameters were compared at the baseline and at 2-year follow-up. SRS-22 score was used for the comparison of clinical outcome. RESULTS: At baseline, Japan showed significantly worse sagittal alignment such as smaller lumbar lordosis (LL), larger pelvic incidence (PI), and larger sagittal vertical axis than United States. However, Japan had significantly fewer levels fused than United States (US, 12.66±4.6; JP, 8.49±2.7). At 2 years after the surgery, Japan still had significantly worse residual sagittal deformity. Comparison of SRS-22 scores revealed Japan had better pain but worse functional domain scores at baseline which improved to comparable levels to the United States at 2 years. Self-image and mental health scores in Japan were significantly worse both at baseline and at 2 years. Analysis of factors affecting SRS-22 satisfaction score at 2 years revealed that previous spinal fusion surgery in the United States and LL, PI-LL, and sagittal vertical axis at 2 years in Japan had significant correlation. CONCLUSIONS: These similarities and discrepancies may be influenced by the cultural or lifestyle differences between both nations and should be considered when interpreting the results of ASD studies among different ethnicities.

The cohort study for the determination of reference values for spinopelvic parameters (T1 pelvic angle and global tilt) in elderly volunteers.

PURPOSE: T1 pelvic angle (TPA) and global tilt (GT) are spinopelvic parameters that account for trunk anteversion and pelvic retroversion. To investigate spinopelvic parameters, especially TPA and GT, in Japanese adults and determine norms for each parameter related to health-related quality of life (HRQOL). MATERIALS AND METHODS: Six hundred and fifty-six volunteers (262 men and 394 women) aged 50-92 years (mean, 72.8 years) were enrolled in this study. The incidence of vertebral fracture, spondylolisthesis and coronal malalignment were measured. Five spinopelvic parameters (TPA, GT, sagittal vertical axis [SVA], pelvic tilt [PT], and pelvic incidence-lumbar lordosis [PI-LL]) were measured using whole spine standing radiographs. The mean values for each parameter were estimated by sex and decade of life. HRQOL measures, including the Oswestry Disability Index (ODI) and EuroQuol-5D (EQ-5D), were also obtained. Pearson's correlation coefficients were determined between each parameter and HRQOL measure. Moreover, the factors contributing to the QOL score were calculated using logistic regression with age, sex, the existence of vertebral fracture and spondylolisthesis, coronal malalignment (coronal curve >30°) and sagittal malalignment (SVA >95 mm) as explanatory variables and the presence of disability (ODI >40) as a free variable. RESULTS: The mean values for the spinopelvic parameters were as follows: TPA, 17.9°; GT, 23.2°; SVA, 50.2 mm; PT, 18.6°; and PI-LL, 7.5°. TPA and GT strongly correlated with each other (r = 0.990) and with the other spinopelvic parameters. TPA and GT correlated with ODI (r = 0.339, r = 0.348, respectively) and EQ-5D (r = -0.285, r = -0.288, respectively), similar to those for SVA. TPA, GT, PT, and PI-LL were significantly higher in women than in men. PT and PI-LL gradually increased with age, while TPA, GT, and SVA tended to deteriorate after the 7th decade. Based on a logistic regression analysis, the deterioration of ODI was mostly affected by the sagittal malalignment. The TPA and GT cut-off values for severe disability (ODI >40) based on linear regression modeling were 26.0° and 33.7°, respectively. CONCLUSIONS: We determined reference values for spinopelvic parameters in elderly volunteers. Similar to SVA, TPA and GT correlated with HRQOL. TPA, GT, PT, and PI-LL were worse in women and progressed with age.