A new study published in the Journal of Neurosurgery: Spine examines the best method to measure sagittal alignment in the cervical spine.
The study authors enrolled 138 patients in a randomized controlled trial with two investigators measuring the C-2 to C-7 angles with Harrison's posterior tangent method and compared to the modified Toyama method. The study authors found:
1. Both measurements had high interrater reliability, measured using Cronbach's alpha. The posterior tangent method reported 0.907 and the modified Toyama technique reported 0.984 scores.
2. The average angle with the Toyama method was 23.4 degrees; the kyphotic cervical spine average angle was -2.2 degrees and for the straight spine the average angle was 10.5 degrees.
3. Study authors concluded the absolute angle measurement between C-2 and C-7 doesn't "unequivocally define" sagittal cervical alignment, as even a positive angle could be present in kyphotic spine based on the minimum and maximum value ranges.
4. The study authors recommended the modified Toyama method as a better tool for global cervical sagittal alignment assessment than Harrison's posterior tangent method.