{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,30]],"date-time":"2026-10-30T21:07:11Z","timestamp":1793394431935,"version":"4.5.0"},"reference-count":30,"publisher":"Asian Spine Journal (ASJ)","issue":"1","license":[{"start":{"date-parts":[[2025,8,25]],"date-time":"2025-08-25T00:00:00Z","timestamp":1756080000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"National Key Research and Development Program of China","award":["2022YFC2407203"],"award-info":[{"award-number":["2022YFC2407203"]}]}],"content-domain":{"domain":["asianspinejournal.org"],"crossmark-restriction":true},"short-container-title":["Asian Spine J"],"published-print":{"date-parts":[[2026,2,28]]},"abstract":"<jats:p>Study Design: Retrospective cross-sectional analysis of 187 consecutive patients undergoing surgical treatment for cervical spondylotic myelopathy (CSM).Purpose: To investigate sexual dimorphism in external occipital protuberance (EOP) hyperplasia morphology and elucidate its clinical correlation with ossification of the nuchal ligament (ONL) and cervical sagittal imbalance. Overview of Literature: Emerging evidence implicates EOP hyperplasia as potential biomarker of chronic neck strain, yet its relationship with ONL and cervical sagittal imbalance remains underexplored in surgical CSM cohorts.Methods: Cervical radiographs were analyzed. EOP hyperplasia was classified into three subtypes with standardized length measurements. Variables encompassed demographics, ONL-related indices, and sagittal parameters. Subtype comparisons and multivariate regression analyses (with EOP length as dependent variable) were conducted.Results: Analysis of 187 CSM patients (64.2% male) identified gender-specific patterns: males exhibited greater EOP length (9.4\u00b16.8 mm vs. 4.6\u00b13.4 mm, p&lt;0.001). Type III EOP demonstrated male predominance (82.4% vs. type I 31.8%, type II 51.4%; p&lt;0.001), with associated longer hyperplasia length (11.6\u00b16.6 mm vs. type II 5.1\u00b11.9 mm, p&lt;0.001). Type III EOP was associated with higher ONL prevalence (type III 64.8% vs. type I 45.5%, type II 41.9%; p=0.010) and longer ONL osteophyte length (type III 18.8\u00b19.8 mm vs. type I 14.2\u00b18.1 mm, type II 14.2\u00b19.4 mm; p=0.046). Multivariate regression confirmed male sex (\u03b2=\u20133.82, p=0.009), ONL osteophyte length (\u03b2=0.16, p=0.017), T1 slope (\u03b2=0.27, p=0.041), and spino-cranial angle (\u03b2=\u20130.19, p=0.009) as factors independently associated with EOP length (adjusted R\u00b2=0.382).Conclusions: Severe EOP hyperplasia exhibits a male-predominant distribution pattern and demonstrates significant radiological associations with ONL and cervical sagittal imbalance in CSM patients. These findings advocate for EOP evaluation in clinical evaluations to identify high-risk biomechanical profiles.<\/jats:p>","DOI":"10.31616\/asj.2025.0109","type":"journal-article","created":{"date-parts":[[2025,8,27]],"date-time":"2025-08-27T00:00:26Z","timestamp":1756252826000},"page":"10-19","update-policy":"https:\/\/doi.org\/10.31616\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Gender-specific patterns of external occipital protuberance hyperplasia: associations with nuchal ligament ossification and cervical sagittal imbalance in myelopathy patients"],"prefix":"10.31616","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7680-3526","authenticated-orcid":true,"given":"Zhaoyang","family":"Gong","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3244-4111","authenticated-orcid":true,"given":"Hanqiu","family":"Sun","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2028-4245","authenticated-orcid":true,"given":"Dachuan","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1010-0120","authenticated-orcid":true,"given":"Xiao","family":"Lu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1286-2738","authenticated-orcid":true,"given":"Siyang","family":"Liu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4849-5343","authenticated-orcid":true,"given":"Ximeng","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3761-5004","authenticated-orcid":true,"given":"Xinlei","family":"Xia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6841-1696","authenticated-orcid":true,"given":"Feizhou","family":"Lyu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-0191-1387","authenticated-orcid":true,"given":"Jianyuan","family":"Jiang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-7724-3540","authenticated-orcid":true,"given":"Fei","family":"Zou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2902-6728","authenticated-orcid":true,"given":"Hongli","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3690-0513","authenticated-orcid":true,"given":"Xiaosheng","family":"Ma","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"16744","reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1016\/s0379-0738(03)00334-7"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1007\/s00276-023-03133-8"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1520\/jfs2002183"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.1002\/ajpa.10373"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7580.2006.00540.x"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.1016\/j.bjps.2015.06.013"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.1111\/joa.12466"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-020-63554-y"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-019-49153-6"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1097\/00007632-200001010-00003"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1016\/0021-9290(85)90202-7"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.5152\/eurasianjmed.2018.17314"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1097\/brs.0000000000000430"},{"key":"ref14","first-page":"461","volume-title":"Comparative roentgenographical study on the incidence of ossification of the posterior longitudinal ligament and other degenerative changes of the cervical spine among Japanese, Koreans, Americans and Germans (author\u2019s transl)","author":"Izawa","year":"1980"},{"key":"ref15","first-page":"E394","volume-title":"Ossification of the posterior longitudinal ligament of the cervical spine in 3161 patients: a CT-based study","author":"Fujimori","year":"2015"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1177\/0284185118778866"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0224729"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.1186\/s12891-019-2569-1"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1016\/j.kjms.2012.04.016"},{"key":"ref20","doi-asserted-by":"publisher","DOI":"10.1097\/00007632-200109010-00011"},{"key":"ref21","doi-asserted-by":"publisher","DOI":"10.1097\/brs.0000000000000037"},{"key":"ref22","doi-asserted-by":"publisher","DOI":"10.3171\/2016.10.spine16632"},{"key":"ref23","doi-asserted-by":"publisher","DOI":"10.1016\/j.clinbiomech.2018.02.004"},{"key":"ref24","doi-asserted-by":"publisher","DOI":"10.1097\/01.brs.0000138309.11926.72"},{"key":"ref25","doi-asserted-by":"publisher","DOI":"10.1007\/s11282-023-00694-7"},{"key":"ref26","doi-asserted-by":"publisher","DOI":"10.1097\/brs.0000000000004735"},{"key":"ref27","doi-asserted-by":"publisher","DOI":"10.1016\/j.actbio.2021.07.046"},{"key":"ref28","doi-asserted-by":"publisher","DOI":"10.3171\/2018.5.spine171232"},{"key":"ref29","doi-asserted-by":"publisher","DOI":"10.1016\/j.wneu.2019.06.193"},{"key":"ref30","doi-asserted-by":"publisher","DOI":"10.1007\/s00586-014-3632-0"}],"container-title":["Asian Spine Journal"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/asianspinejournal.org\/upload\/pdf\/asj-2025-0109.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/asianspinejournal.org\/journal\/view.php?doi=10.31616\/asj.2025.0109","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/asianspinejournal.org\/upload\/pdf\/asj-2025-0109.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T00:57:54Z","timestamp":1772153874000},"score":1,"resource":{"primary":{"URL":"http:\/\/asianspinejournal.org\/journal\/view.php?doi=10.31616\/asj.2025.0109"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,28]]},"references-count":30,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,2]]}},"URL":"https:\/\/doi.org\/10.31616\/asj.2025.0109","relation":{},"ISSN":["1976-1902","1976-7846"],"issn-type":[{"value":"1976-1902","type":"print"},{"value":"1976-7846","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,28]]},"assertion":[{"value":"2025-02-26","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-05-24","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-08-25","order":2,"name":"published","label":"Published online","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-02-28","order":3,"name":"published","label":"Print publication","group":{"name":"publication_history","label":"Publication History"}}]}}