Cervical spine lateral radiograph versus whole spine lateral radiograph: A retrospective comparative study to identify a better modality to assess cervical sagittal alignment

This study is aimed to compare whole-spine lateral radiograph (WLR) and cervical lateral radiograph (CLR) in terms of T1 slope visibility and cervical sagittal parameters and to identify the superior imaging modality for assessment of cervical sagittal parameters. 1. T1 slope visibility, 2. T1 slope, 3. C7 slope, 4. C0–C2 Cobb angle (CAC0–C2), 5. C2–C7 Cobb angle (CAC2–C7), and 6. cervical sagittal vertical axis (cSVA). The visibility of the T1 slope was significantly lower with WLR than with CLR (28.3% vs 83.3%, P = .049). The mean CAC2–C7 on WLR was significantly less lordotic than that on CLR (11.2 ± 9.2° vs 14.3 ± 11.3°; P = .01). The mean cSVA was translated more posteriorly on WLR than on CLR (9.9 ± 18.9 mm vs 15.0 ± 13.4 mm, P = .04). However, no significant differences in T1 slope, C7 slope, and CAC0–C2 were found between CLR and WLR. This study shows that standing CLR could provide better visualization of the upper endplate of T1. Furthermore, WLR taken in hands on clavicle position distorted radiographic measurements such as CAC2-C7 and cSVA. Therefore, CLR performed in the standing position seems to allow more-accurate measurements of cervical sagittal parameters.