{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T13:47:51Z","timestamp":1790776071687,"version":"4.1.0"},"reference-count":51,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"19","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2020,10,7]]},"abstract":"\n Background:<\/jats:title>\n Cervical alignment is vital for maintaining horizontal gaze and sagittal balance. The aims of this study were to summarize previously published descriptions of normative cervical alignment and to analyze a cohort of asymptomatic volunteers in order to identify natural clusters of normal radiographic parameters.<\/jats:p>\n <\/jats:sec>\n \n Methods:<\/jats:title>\n We performed a systematic review of the literature on radiographic measurements of asymptomatic volunteers through a search of MEDLINE and ScienceDirect databases. We then performed an analysis of demographic and radiographic parameters of volunteers without back or neck complaints. Only subjects with a chin-brow vertical angle (CBVA) within previously published normal limits were retained for analysis. A 2-step cluster analysis was used to find natural groups of cervical alignment. Differences among groups were investigated with a post hoc analysis of variance (ANOVA).<\/jats:p>\n <\/jats:sec>\n \n Results:<\/jats:title>\n We included 37 articles in our analysis. There was a broad spectrum of both C2-C7 lordosis-kyphosis and T1 slope across ages and sexes. Of the 119 asymptomatic volunteers who were available for analysis, 84 (with a mean age [and standard deviation] of 49.0 \u00b1 17.1 years) had a CBVA ranging from \u22124.7\u00b0 to 17.7\u00b0. The cluster analysis identified 3 alignment groups based on cervical lordosis-kyphosis and T1 slope (silhouette measure of cohesion, >0.6). Twenty-seven volunteers (32.1%) were identified as the \u201ckyphotic curve cohort\u201d (KCC) (mean C2-C7 Cobb angle, \u22128.6\u00b0 \u00b1 7.3\u00b0; mean T1 slope, 17.4\u00b0 \u00b1 6.6\u00b0), 43 volunteers (51.2%) were identified as the \u201cmedium lordosis cohort\u201d (MLC) (mean C2-C7 Cobb angle, 8.7\u00b0 \u00b1 7.2\u00b0; mean T1 slope, 26.6\u00b0 \u00b1 4.0\u00b0), and 14 volunteers (16.7%) were identified as the \u201clarge lordosis cohort\u201d (LLC) (mean C2-C7 Cobb angle, 21.2\u00b0 \u00b1 7.2\u00b0, mean T1 slope, 39.5\u00b0 \u00b1 6.4\u00b0) (p < 0.001 for both). Moving from KCC to LLC, there was a significant decrease in C0-C2 lordosis (p = 0.016). Examination of the cervical vertebral orientation demonstrated that C4 had a constant orientation relative to the horizontal (p = 0.665). Correlation analysis between C2-C7 and vertebral orientations again demonstrated that C4 orientation was independent of C2-C7 alignment.<\/jats:p>\n <\/jats:sec>\n \n Conclusions:<\/jats:title>\n We have identified 3 morphotypes of the cervical spine based on C2-C7 alignment and T1 slope. These findings demonstrate the broad definition of normal cervical alignment and the range of cervical lordosis-kyphosis that is acceptable.<\/jats:p>\n <\/jats:sec>","DOI":"10.2106\/jbjs.19.01384","type":"journal-article","created":{"date-parts":[[2020,8,26]],"date-time":"2020-08-26T16:01:20Z","timestamp":1598457680000},"page":"e109","source":"Crossref","is-referenced-by-count":29,"title":["The 3 Sagittal Morphotypes That Define the Normal Cervical Spine"],"prefix":"10.2106","volume":"102","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9617-1987","authenticated-orcid":false,"given":"Sohrab","family":"Virk","sequence":"first","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4820-1835","authenticated-orcid":false,"given":"Renaud","family":"Lafage","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7190-7692","authenticated-orcid":false,"given":"Jonathan","family":"Elysee","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4787-1538","authenticated-orcid":false,"given":"Philip","family":"Louie","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7482-6994","authenticated-orcid":false,"given":"Han Jo","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Todd","family":"Albert","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5595-4958","authenticated-orcid":false,"given":"Lawrence G.","family":"Lenke","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Columbia University, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6666-725X","authenticated-orcid":false,"given":"Frank","family":"Schwab","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0119-7111","authenticated-orcid":false,"given":"Virginie","family":"Lafage","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2020,7,13]]},"reference":[{"key":"bib1-20230811","doi-asserted-by":"crossref","DOI":"10.1097\/00003086-197506000-00011","article-title":"Biomechanical analysis of clinical stability in the cervical spine","volume":"109","author":"White","year":"1975","journal-title":"Clin Orthop Relat Res."},{"issue":"6","key":"bib2-20230811","doi-asserted-by":"crossref","DOI":"10.1097\/BRS.0b013e3181908c7b","article-title":"Task-specific frequencies of neck motion measured in healthy young adults over a five-day period","volume":"34","author":"Cobian","year":"2009","journal-title":"Spine (Phila Pa 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(Phila Pa 1976)."},{"issue":"6","key":"bib46-20230811","doi-asserted-by":"crossref","DOI":"10.1007\/s00402-011-1265-x","article-title":"Relation between alignments of upper and subaxial cervical spine: a radiological study","volume":"131","author":"Guo","year":"2011","journal-title":"Arch Orthop Trauma Surg."},{"issue":"1","key":"bib47-20230811","article-title":"Relationship between alignment of upper and lower cervical spine in asymptomatic individuals","volume":"99","author":"Nojiri","year":"2003","journal-title":"J Neurosurg."},{"issue":"11","key":"bib48-20230811","doi-asserted-by":"crossref","DOI":"10.1097\/BRS.0b013e3181f9f714","article-title":"Impact of the O-C2 angle on the oropharyngeal space in normal patients","volume":"36","author":"Ota","year":"2011","journal-title":"Spine (Phila Pa 1976)."},{"issue":"1","key":"bib49-20230811","doi-asserted-by":"crossref","DOI":"10.1007\/s00586-014-3525-2","article-title":"Does whole-spine lateral radiograph with clavicle positioning 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Part I: Radiographic data from over 1,200 asymptomatic subjects","volume":"21","author":"Yukawa","year":"2012","journal-title":"Eur Spine J."}],"container-title":["Journal of Bone and Joint Surgery"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.ovid.com\/10.2106\/JBJS.19.01384","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T13:45:33Z","timestamp":1787751933000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ovid.com\/10.2106\/JBJS.19.01384"}},"subtitle":["A Systematic Review of the Literature and an Analysis of Asymptomatic Volunteers"],"short-title":[],"issued":{"date-parts":[[2020,7,13]]},"references-count":51,"journal-issue":{"issue":"19","published-print":{"date-parts":[[2020]]}},"URL":"https:\/\/doi.org\/10.2106\/jbjs.19.01384","relation":{},"ISSN":["0021-9355","1535-1386"],"issn-type":[{"value":"0021-9355","type":"print"},{"value":"1535-1386","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,7,13]]}}}