Background context: The lumbar spine latericumbent and full-length lateral standing radiographs are most commonly used to assess lumbar disorder. However, there are few literatures on the difference and correlation of the sagittal parameters between the two shooting positions.
Purpose: The study aimed to investigate the difference of sagittal parameters in spine lateral radiographs between latericumbent and upright positions, identify the correlation, and establish a preliminary linear fitting formula.
Study design: The study is a prospective study on radiographic evaluation of sagittal alignment using latericumbent and upright positions.
Patient sample: One hundred fifty-seven patients were recruited from the orthopedics clinic of a single medical center.
Outcome measure: Angle measurement, the intra- and interobserver measurement reliability of measurement, and analysis of the angle measurement were carried out.
Method: The sagittal alignment of 157 patients were assessed using Surgimap software from two kinds of lateral radiographs to acquire the following parameters: lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), L4-L5 intervertebral angle (IVA4-5), L4-L5 intervertebral height index (IHI4-5), and PI-LL. The Kolmogorov-Smirnov test, paired t test, Pearson correlation analysis, and multivariate linear regression analysis were used to analyze the data.
Results: The results showed significantly statistical difference in LL, SS, PT, IVA4-5, and PI-LL, except for PI and IHI4-5, between the two positions. There was a significant relativity between standing LL and latericumbent LL (r=0.733, p<.01), PI (r=0.611, p<.01), and SS (r=0.626, p<.01). The predictive formula of standing LL was 12.791+0.777 latericumbent LL+0.395 latericumbent PI-0.506 latericumbent SS (adjusted R2=0.619, p<.05).
Conclusion: Not all of sagittal parameters obtained from two positions are identical. Thus, the full-spine lateral standing films are difficult to be replaced. The surgeon should give sufficient consideration to the difference between the two views. We may primarily predict standing LL with the formula when we could not get whole-spine lateral standing radiographs.
Keywords: Correlation; Difference; Full-length lateral standing radiograph; Lumbar spine Latericumbent radiograph; Radiographic comparison; sagittal alignment.
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