{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T12:04:10Z","timestamp":1784203450325,"version":"3.55.0"},"reference-count":25,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["SPI"],"published-print":{"date-parts":[[2009,5]]},"abstract":"<jats:sec>\n<jats:title>Object<\/jats:title>\n<jats:p>The object of this study was to describe an unusual fracture subtype within C-1 injuries with a propensity to result in late deformity and pain. Most patients with C-1 injuries are nonsurgically treated using external immobilization unless there is an injury of the transverse atlantal ligament. The authors describe an unusual variant involving a unilateral sagittal split with a high tendency to late deformity and pain. They also review the literature and treatment of C-1 fractures.<\/jats:p><\/jats:sec>\n<jats:sec>\n<jats:title>Methods<\/jats:title>\n<jats:p>A retrospective review of 12,671 CT scans from a Level I trauma center over a 6-year period yielded 54 patients with C-1 fractures. Among these patients, 6 had an unusual unilateral lateral mass sagittal split, which resulted in a late cock-robin deformity in all survivors and thus a surgical deformity correction with occipital-cervical instrumented fusions. Patient charts and radiographs were reviewed, this fracture subtype is described, and its treatment discussed.<\/jats:p><\/jats:sec>\n<jats:sec>\n<jats:title>Results<\/jats:title>\n<jats:p>Radiographic studies in 6 patients with C-1 fractures demonstrated a unilateral sagittal split of the lateral mass but an intact transverse atlantal ligament. In the 3 surviving patients, a late cock-robin deformity, significant loss of neck rotation, and severe neck pain developed. Vertebral artery occlusion, as revealed on CT angiography, occurred in 1 patient. All patients were placed in traction and underwent successful occipital-cervical fusion and deformity correction. At the final follow-up, all patients had satisfactory pain relief and improved head alignment.<\/jats:p><\/jats:sec>\n<jats:sec>\n<jats:title>Conclusions<\/jats:title>\n<jats:p>Patients with a unilateral sagittal split of the C-1 lateral mass have unstable injuries and must be carefully monitored, with a low threshold for surgical reconstruction or prolonged traction. Patients with late deformity can be successfully treated with occipital-cervical instrumented fusions.<\/jats:p><\/jats:sec>","DOI":"10.3171\/2009.1.spine08708","type":"journal-article","created":{"date-parts":[[2009,9,28]],"date-time":"2009-09-28T22:26:29Z","timestamp":1254176789000},"page":"466-473","source":"Crossref","is-referenced-by-count":39,"title":["Unilateral C-1 lateral mass sagittal split fracture: an unstable Jefferson fracture variant"],"prefix":"10.3171","volume":"10","author":[{"given":"Richard","family":"Bransford","sequence":"first","affiliation":[{"name":"Departments of Orthopaedics and Sports Medicine and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexis","family":"Falicov","sequence":"additional","affiliation":[{"name":"Seattle Orthopaedic and Fracture Clinic, Seattle, Washington"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Quynh","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Radiology, Harborview Medical Center, University of Washington; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jens","family":"Chapman","sequence":"additional","affiliation":[{"name":"Departments of Orthopaedics and Sports Medicine and"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1754","reference":[{"key":"b1-0100466","series-title":"Spine","doi-asserted-by":"publisher","first-page":"2713","DOI":"10.1097\/00007632-199812150-00011","article-title":"Cervical spine trauma","volume":"23","author":"An","year":"1998"},{"key":"b2-0100466","series-title":"Spine","doi-asserted-by":"publisher","first-page":"1832","DOI":"10.1097\/00007632-199809010-00005","article-title":"A biomechanical study of Jefferson fractures","volume":"23","author":"Beckner","year":"1998"},{"key":"b3-0100466","series-title":"Radiology","doi-asserted-by":"publisher","first-page":"117","DOI":"10.1148\/radiology.212.1.r99jl08117","article-title":"Cervical spine screening with CT in trauma patients: a cost-effectiveness analysis","volume":"212","author":"Blackmore","year":"1999"},{"key":"b4-0100466","series-title":"Unfallchirurg","first-page":"754","article-title":"[Direct osteosynthesis of instable Gehweiler Type III atlas fractures. 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