Abstract
Introduction
In the past 10 years, the importance of the sagittal shape of human pelvis has been pointed out by the orthopedists. However, most studies were defined in Western and Korean populations. It is unclear whether these characteristics of Chinese spinopelvic sagittal alignment differ from those of western and Korean populations. In addition, the predictive equation of lumbar lordosis remains unclear. This study described normal types of spinopelvic sagittal alignment in Chinese asymptomatic subjects, and investigated a prediction equation of lumbar lordosis from selective spinal and pelvic sagittal parameters.
Material and Methods
This was a prospective radiological analysis using full-spine standing lateral radiographs of Chinese volunteers. A total of 171 volunteers (94 males and 77 females; mean age, 23 years [range, 18–28 years]) participated. Pelvic and spinal parameters were measured according to geometric characteristics. The Pearson correlation test was calculated, regression analysis was running with the lumbar lordosis (predicted variable), and the other spinal and pelvic parameters (predictor variables), to determine the best sets of predictors to include in the model.
Results
Mean pelvic incidence was 44.6 ± 9.5 degrees, significantly less than that reported in Western subjects. The volunteers were classified into four types according to the location of their apex of total lumbar lordosis. As the apex of total lumbar lordosis moved cranially, lordosis tilt decreased, whereas lower lumbar lordosis, pelvic incidence, sacral slope, and the number of vertebral bodies included in the lower lumbar lordosis increased. On the basis of the pelvic incidence, total lumbar lordosis predictive equation was 0.639 PI + 20.593 degrees. Preliminary prediction of lower lumbar lordosis was PI-10 degrees.
Conclusion
The sagittal alignment of Chinese population could be classified into four types, and was different from that of Caucasian. Lower lumbar lordosis comprised most of total lumbar lordosis, the role of pelvic incidence in determining the sagittal curve was mainly through the adjustment of lower lumbar lordosis. Using regression analysis, total lumbar lordosis could be precisely predicted in asymptomatic subjects. To optimally plan surgery for spinal deformity, the prediction of postoperative lower lumbar lordosis curvature was equally important as that of total lumbar lordosis.