• Ying-Zhao Yan, Zhen-Xuan Shao, Xiang-Xiang Pan, Shao-Qing Chen, Ai-Min Wu, Nai-Feng Tian, Yao-Sen Wu, and Xiang-Yang Wang.
• Department of Orthopaedic Surgery, Zhejiang Spine Surgery Centre, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.
• World Neurosurg. 2018 Dec 1; 120: e488-e496.

ObjectiveWe sought to acquire the whole sagittal spine parameters and investigated the acceptable chin-brow vertical angle (CBVA) for neutral position radiography in an asymptomatic Chinese population.MethodsThe parameters measured in 257 asymptomatic volunteers included CBVA, occipital slope, orbital tilt, occipital incidence, C0-C2 Cobb angle, C2-C7 Cobb angle, C1-C7 Cobb angle, C2-C7 sagittal vertical axis and absolute rotation angle, cervical tilt, cranial tilt, T1 slope, and thoracic kyphosis, and others. We used Pearson correlation analyses to find relationships between CBVA and other variables. The subjects were divided into 5 groups according to the CBVA percentile: group A, 0%-20% CBVA; group B, 20%-40% CBVA; group C, 40%-60% CBVA; group D, 60%-80% CBVA; and group E, 80%-100% CBVA. We used analysis of variance to analyze differences among the 5 groups.ResultsOrbital tilt, Occipital incidence, C1-C7 Cobb angle, C2-C7 sagittal vertical axis, and cranial tilt all increased with increasing CBVA (P < 0.001). The occipital slope, C2-C7 Cobb angle, C2-C7 absolute rotation angle, cervical tilt, T1 slope, and thoracic kyphosis decreased with decreasing CBVA (P < 0.05). No correlations between other sagittal parameters and the CBVA were found. A slight deviation was found in groups B-D, with a greater deviation in groups A, C, and E.ConclusionsAn acceptable range of -1.5° to 5.8° is recommended for the CBVA for cervical radiography in the neutral position. When spinal surgeons evaluate the cervical plane, the effects of the CBVA deviation on cervical curvature must be considered.Copyright © 2018 Elsevier Inc. All rights reserved.

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