title: Analysis of radiography findings of ossification of nuchal ligament of cervical spine in patients with cervical spondylosis.
abstract: METHODS
  Retrospective clinical data analysis.
  
  
  OBJECTIVE
  This study was conducted to investigate the incidence, related factors, and radiography findings of ossification of the nuchal ligament (ONL) in patient with cervical spondylosis, which could serve as a basis for further studies of the relationships between ONL and cervical spondylosis.
  
  
  BACKGROUND
  Injury to nuchal ligament, which might cause ONL, may aggravate cervical spine instability, leading to cervical spondylosis. Thus, it is important to understand the characteristics of ONL in patients who are diagnosed with cervical spondylosis.
  
  
  METHODS
  Medical records of 372 patients with cervical spondylosis were reviewed. Data analysis included patients' sex, age, location and classification of ONL, and ossification of the posterior longitudinal ligament (OPLL). Radiological features were evaluated by lateral plain radiography and computed tomography for 2-dimensional sagittal plane reconstruction.
  
  
  RESULTS
  Of the 372 patients with cervical spondylosis, 49.7% had a diagnosis of ONL; the incidence of ONL was higher in males than in females (P = 0.001) and in elderly patients than in young patients (P = 0.005). The varying pictures of ONL on the plain radiography were classified into 5 types: local, continuous, segmental, mixed, and unclassified, and the distribution was 49.7%, 33.0%, 3.2%, 8.6%, and 5.4%, respectively. ONL occurred mostly at the level of C4,5 (75.7%) and C5,6 (81.1%). The incidence of ONL was higher in patients with OPLL than others (P < 0.001), and the incidence of multilevel ONL was higher in patients with OPLL than in patients with ONL only (P = 0.038).
  
  
  CONCLUSIONS
  The incidence of ONL is 49.7% in patients with cervical spondylosis. Sex, age, and OPLL are related factors of ONL. ONL can be classified into different types through morphology. Local type is the most common type of ONL, and multilevel ONL occurs mostly in patients with OPLL. C4,5 and C5,6 are the levels where ONL occurs mostly.
  
  
  METHODS
  4.
authors.affiliation: From the Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Zou
authors.forename: Jianyuan
authors.initials: J
authors.lastname: Jiang
authors.forename: Feizhou
authors.initials: F
authors.lastname: Lu
authors.forename: Wenjun
authors.initials: W
authors.lastname: Chen
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Ma
authors.forename: Xinlei
authors.initials: X
authors.lastname: Xia
authors.forename: Lixun
authors.initials: L
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008022:Ligaments / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging*; D011859:Radiography; D012189:Retrospective Studies; D055009:Spondylosis / Q000000981:diagnostic imaging*