• Ho Jin Lee, Jung Hee Kim, Il Sup Kim, and Jae Taek Hong.
• Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, South Korea; Department of Neurosurgery, St. Vincent's Hospital, The Catholic University of Korea, Seoul, South Korea.
• World Neurosurg. 2019 Feb 1; 122: e1222-e1227.

BackgroundThe objective of this study was to evaluate the physiologic change of cervical spine (CS) alignment between 2 radiographs (whole spine [WS] and CS).MethodsMultilevel cervical segmental angles (horizontal gaze, C2 slope, C7 slope, and T1 slope) were measured, and C0-2 angle, C0-7 angle, and C2-7 angle were also calculated. The relative translation statuses of C2-7 sagittal vertical axis and C0-7 sagittal vertical axis were measured.ResultsGenerally, statistically significant differences were found for occipital-slope (Δ7.1°) and C7 slope (Δ2.1°), and these results induced a significant C0-2 angle (Δ4.6°) and nonsignificant C2-7 angle (Δ1.2°) change between the 2 types of radiographs. In the fixed horizontal gaze group analysis, C7 slope and C2-7 angle were significantly different between WS and CS radiographs. In the nonfixed horizontal gaze group analysis, C7 slope exhibited significant upward movement (Δ3.7°), and C7 slope did not showed significant change (Δ0.1°), which caused the constant value of cervical lordosis (C2-7 angle) between the 2 radiographs (P = 0.084).ConclusionsHorizontal gaze fixation may induce untruthful results of cervical lordosis (C2-7 angle) and a nonphysiologic distribution ratio of cervical lordosis (C0-2 angle, 92% vs. C2-7 angle, 8%). However, if the horizontal gaze is not controlled, WS radiographs exhibit a constant value of the C7 slope compared with CS radiographs, which may induce the unchanged state of cervical lordosis and physiologic distribution ratio of cervical lordosis (C0-2 angle, 74% vs. C2-7 angle, 26%).Copyright © 2018 Elsevier Inc. All rights reserved.

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