title: Influence of T1 Slope on the Cervical Sagittal Balance in Degenerative Cervical Spine: An Analysis Using Kinematic MRI.
abstract: METHODS
  A retrospective kinematic magnetic resonance imaging (kMRI) study.
  
  
  OBJECTIVE
  To evaluate the utility of kMRI in determining the relationship between cervical sagittal balance and TI alignment.
  
  
  BACKGROUND
  Thoracic inlet parameters play an important role in cervical spine sagittal balance. However, most of the literature is based on lower resolution cervical X-rays or CT scans in the supine position.
  
  
  METHODS
  Cervical spine kMRI of 83 patients with degenerative cervical spine conditions (20-68 yr of age) was analyzed for: (1) cervical spine parameters: C2-C7 angle, C2-C7 sagittal vertical axis (SVA), cranial tilt, and cervical tilt; and (2) T1 parameters: thoracic inlet angle (TIA), T1 slope, and neck tilt (NT). Multiple logistic regression analysis and Pearson correlation coefficients were performed.
  
  
  RESULTS
  The mean TIA, T1 slope, and NT were 78.0, 33.2, and 44.8°, respectively. The mean C2-7 angle, SVA of C2-C7, cervical tilt, and cranial tilt were -15.4°, 22.0 mm, 18.1°, and 15.1°, respectively. The ratio of cervical:cranial tilt was maintained as 55:45%. A significant correlation was found between the C2-C7 angle and T1 slope (r = 0.731), TIA and C2-C7 angle (r = 0.406), cervical tilt with C2-C7 angle (r = 0.671), T1 slope with TIA (r = 0.429), TIA with neck tilt (r = 0.733), TIA with cervical tilt (r = 0.377), SVA C2-C7 with cervical tilt (r = -0.480), SVA C2-C7 with cranial tilt (r = 0.912), and C2-7 SVA with the ratio of cranial tilt to cervical tilt (r = 0.694).
  
  
  CONCLUSIONS
  An individual with a large T1 slope required large cervical lordosis to preserve physiologic sagittal balance of the cervical spine. Cranial tilt was the cervical parameter most strongly correlated with SVA C2-C7, and thus may be a good parameter to assess decompensation of cervical sagittal balance.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA†Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA‡Orthopaedic Department, Tongde Hospital of Zhejiang Province, Hangzhou, China§Department of Spine Surgery, First Hospital of Jilin University, Changchun, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Weng
authors.forename: Justin
authors.initials: J
authors.lastname: Wang
authors.forename: Alexander
authors.initials: A
authors.lastname: Tuchman
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Changfeng
authors.initials: C
authors.lastname: Fu
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Hsieh
authors.forename: Zorica
authors.initials: Z
authors.lastname: Buser
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D012189:Retrospective Studies; D055815:Young Adult