Differences in lumbar and pelvic parameters among African American, Caucasian and Asian populations.

PURPOSE: Ethnic differences in spino-pelvic parameters among a healthy population are poorly defined in the literature. The purpose of this study was to document sagittal spino-pelvic parameters in a sample of African Americans and to compare them with previously reported data for Caucasians and Asians. METHODS: African American individuals without spine pathology who had standing lateral radiographs were identified. Radiographs were measured to determine the following parameters: lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). Data of adult subjects were compared with those previously published for Caucasians (n = 709) and Asians (n = 312). RESULTS: These measurements (LL, PI, PT, and SS) obtained for the 36 African American subjects aged 18 years or older [15 men and 21 women; mean age 26.6 ± 8.7 range (18-53)] The mean LL, PI, PT and SS values were 57.2°, 57.7°, 15.9° and 41.4°, respectively. A comparative analysis showed the means values for PI was greater in the African American than in Caucasian (57.7° vs. 52.6°, p = 0.007), and than in Asian (57.7° vs. 48.7°, p < 0.001). The linear regression model for the LL as a function of PI were "predict LL = 0.41 × PI + 33.7" in African American, "predict LL = 0.58 × PI + 24.3" in Caucasian, and "predict LL = 0.54 × PI + 22.0" in Asian, respectively. CONCLUSION: Significant differences in sagittal spino-pelvic parameters among races were seen. These differences should be considered when planning surgical reconstruction for spinal surgery. These slides can be retrieved under Electronic Supplementary Material.

Normative values for the spine shape parameters using 3D standing analysis from a database of 268 asymptomatic Caucasian and Japanese subjects.

PURPOSE: Sagittal balance analysis has gained importance and the measure of the radiographic spinopelvic parameters is now a routine part of many interventions of spine surgery. Indeed, surgical correction of lumbar lordosis must be proportional to the pelvic incidence (PI). The compensatory mechanisms [pelvic retroversion with increased pelvic tilt (PT) and decreased thoracic kyphosis] spontaneously reverse after successful surgery. MATERIALS AND METHODS: This study is the first to provide 3D standing spinopelvic reference values from a large database of Caucasian (n = 137) and Japanese (n = 131) asymptomatic subjects. RESULTS: The key spinopelvic parameters [e.g., PI, PT, sacral slope (SS)] were comparable in Japanese and Caucasian populations. Three equations, namely lumbar lordosis based on PI, PT based on PI and SS based on PI, were calculated after linear regression modeling and were comparable in both populations: lumbar lordosis (L1-S1) = 0.54*PI + 27.6, PT = 0.44*PI - 11.4 and SS = 0.54*PI + 11.90. CONCLUSION: We showed that the key spinopelvic parameters obtained from a large database of healthy subjects were comparable for Causasian and Japanese populations. The normative values provided in this study and the equations obtained after linear regression modeling could help to estimate pre-operatively the lumbar lordosis restoration and could be also used as guidelines for spinopelvic sagittal balance.

Estimation of the Ideal Lumbar Lordosis to Be Restored From Spinal Fusion Surgery: A Predictive Formula for Chinese Population.

STUDY DESIGN: A prospective, cross-sectional study. OBJECTIVE: To determine the independent variables associated with lumbar lordosis (LL) and to establish the predictive formula of ideal LL in Chinese population. SUMMARY OF BACKGROUND DATA: Several formulas have been established in Caucasians to estimate the ideal LL to be restored for lumbar fusion surgery. However, there is still a lack of knowledge concerning the establishment of such predictive formula in Chinese population. METHODS: A total of 296 asymptomatic Chinese adults were prospectively recruited. The relationships between LL and variables including pelvic incidence (PI), age, sex, and body mass index were investigated to determine the independent factors that could be used to establish the predictive formula. For the validation of the current formula, other 4 reported predictive formulas were included. The absolute value of the gap between the actual LL and the ideal LL yielded by these formulas was calculated and then compared between the 4 reported formulas and the current one to determine its reliability in predicting the ideal LL. RESULTS: The logistic regression analysis showed that there were significant associations of LL with PI and age (R = 0.508, P < 0.001 for PI; R = 0.088, P = 0.03 for age). The formula was, therefore, established as follows: LL = 0.508 × PI - 0.088 × Age + 28.6. When applying our formula to these subjects, the gap between the predicted ideal LL and the actual LL was averaged 3.9 ± 2.1°, which was significantly lower than that of the other 4 formulas. CONCLUSION: The calculation formula derived in this study can provide a more accurate prediction of the LL for the Chinese population, which could be used as a tool for decision making to restore the LL in lumbar corrective surgery. LEVEL OF EVIDENCE: 3.

Comparison of sagittal spinopelvic alignment in Chinese adolescents with and without idiopathic thoracic scoliosis.

STUDY DESIGN: A retrospective radiographical study investigated the sagittal alignment in healthy Chinese girls and Chinese girls with idiopathic thoracic scoliosis (T-AIS). OBJECTIVE: To evaluate the sagittal alignment of the pelvis and spine in Chinese girls with idiopathic scoliosis and healthy girls and to assess whether the pelvic morphology differed between white and Chinese girls with AIS. SUMMARY OF BACKGROUND DATA: It has been shown that patients with AIS have an abnormal spinopelvic balance and pelvic morphology. Race is a determinant factor of sagittal spinal alignment and serves as a reminder when planning surgical reconstruction for spinal deformity. Until now, there have been no studies documenting the sagittal lumbosacral spine morphology in Chinese girls with T-AIS. METHODS: In this study, 95 patients with T-AIS and 33 healthy age-matched adolescents were recruited consecutively. Sagittal spinal and pelvic parameters were measured from the standing lateral radiograph, including thoracic kyphosis (TK), lumbar lordosis (LL), upper arc of LL, lower arc of LL, pelvic incidence (PI), sacrum slope (SS), and pelvic tilt (PT). Analysis of variance was used in the comparison of each dependent variable between patients with AIS and healthy adolescents. The relations between all parameters were determined via Pearson correlation coefficient (r). RESULTS: For all the sagittal parameters, only the TK and the upper arc of the LL showed significant differences between girls with AIS and healthy girls. The LL, lower arc of the LL, and 3 pelvic parameters were similar for both groups. The TK was found to be strongly correlated with LL and the upper arc of the LL in both groups. However, the TK was not related to the lower arc of the LL, nor were the 3 pelvic parameters in either group. In addition, LL was found to be associated with PI and SS in both groups. The lower arc of the LL was also correlated with PI for both groups. The PI was related to PT and SS in both groups; however, no correlation was found between PT and SS. In this study, the TK (15.7°), SS (35.1°), and PI (44.2°) were found to be significantly lower in Chinese patients with T-AIS than the values reported in the AIS cohort. CONCLUSION: In our study, the Chinese girls with T-AIS had similar PI, PT, and SS values when compared with the age-matched healthy girls. There were significant differences in pelvic morphology between Chinese and white girls with AIS. These results suggest that race may influence an individual's spinopelvic morphology. Although we have shown that the TK could affect LL through the upper arc of the LL directly, the evaluation of the thoracolumbar morphology of T-AIS before surgery is important for surgical planning.

Normal patterns of sagittal alignment of the spine in young adults radiological analysis in a Korean population.

STUDY DESIGN: Radiological analysis and classification of normal patterns of sagittal alignment of the spine. OBJECTIVE: To classify the patterns of sagittal alignment of the spine in young asymptomatic adults and analyze the differences in the various spinal and pelvic parameters according to these patterns. SUMMARY OF BACKGROUND DATA: Previous studies reported that the overall sagittal pattern and balance were more important than the normative values. There are few studies on white populations, classifying the normal patterns of sagittal curvature, and no studies on Asian populations. METHODS: Whole spine, standing lateral radiographs of 86 Korean volunteers were taken. The pelvic and spinal parameters (total thoracic kyphosis, horizontal thoracic level, thoracolumbar junctional angle (TLJA), total lumbar lordosis, lower lumbar lordosis, horizontal lumbar level (HLL), lumbar inclination, pelvic tilt, sacral slope (SS), pelvic incidence, spinal balance, spinopelvic balance, and sacropelvic balance) were measured and the correlations of all parameters were analyzed. The volunteers were classified in to three types according to their HLL. The data were analyzed statistically to determine the differences in the parameters and balance between the three types. RESULTS: The HLL showed a significant correlation with the lumbar inclination, junctional level, TLJA, spinal balance, spinopelvic balance, and SS on analyzing the correlation of the parameters. As HLL moved caudally, the TLJA and lumbar inclination increased, whereas the lower lumbar lordosis, pelvic incidence, and SS decreased and spinal balance became more negative. There were no significant differences in total thoracic kyphosis and sacropelvic balance between the three types. CONCLUSION: The patterns of sagittal alignment could be classified into three types showing that the spinal balance becomes more negative, the lumbar inclination and TLJA increase, the SS and pelvic incidence decrease, and lumbar lordotic curves becomes shorter as the patterns of sagittal curvature move toward type 3. This classification in young adults should be considered individually as a reference for surgeons aiming to restore the lumbar lordosis and sagittal alignment in degenerative lumbar fusion surgery.