title: Kinematic relationship between missed ligamentum flavum bulge and degenerative factors in the cervical spine.
abstract: BACKGROUND
  Bulging of ligamentum flavum can happen with the aging process and can lead to compression of the spinal cord and nerves. However, the distribution and the risk factors associated with a missed ligamentum flavum bulge (LFB) are unknown.
  
  
  OBJECTIVE
  The aim was to evaluate the distribution and risk factors associated with missed LFB in the cervical spine.
  
  
  METHODS
  This was a retrospective analysis of kinematic magnetic resonance images (kMRI).
  
  
  METHODS
  Patients diagnosed with symptomatic neck pain or radiculopathy between March 2011 and October 2012 were included.
  
  
  METHODS
  The outcome measures were missed LFB and degenerative factors.
  
  
  METHODS
  A total of 200 patients (1,000 cervical segments) underwent upright kMRI in neutral, flexion, and extension postures. The LFB, sagittal cervical angles, disc herniation, disc degeneration, disc height, angular motion, translational motion, age, and gender were recorded. After excluding segments with LFB in neutral and flexion position, Pearson and Spearman correlation coefficients were used to evaluate the relation between the risk factors and missed LFB in the extension position.
  
  
  RESULTS
  The average depth of LFB was 0.24±0.71 mm at C2-C3, 1.02±1.42 mm at C3-C4, 1.65±1.48 mm at C4-C5, 2.13±1.37 mm at C5-C6, and 1.05±1.54 mm at C6-C7. The distribution of LFB was the most frequent at C5-C6 level (76.58%) followed by C4-C5 (63.06%). Disc herniation, disc degeneration, angular variation, and translational motion were significantly correlated with missed LFB at C4-C5 andC5-C6. Disc degeneration was the only factor significantly correlated with missed LFB at all cervical segments.
  
  
  CONCLUSIONS
  Occurrence and depth of missed LFB was the highest at C4-C5 and C5-C6 compared with other cervical levels. Disc degeneration, disc herniation, angular variation, and translational motion could play a role in the development of LFB at C4-C5 andC5-C6.
authors.affiliation: Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, 1520 San Pablo St., Suite 2000 Los Angeles, CA 90033, USA; Department of Orthopaedic Surgery, Renji Hospital, Jiaotong University School of Medicine, No. 160, Pujian Road, Pudong New Area, 200127 Shanghai, China.
authors.forename: Guibin
authors.initials: G
authors.lastname: Zhong
authors.affiliation: Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, 1520 San Pablo St., Suite 2000 Los Angeles, CA 90033, USA. Electronic address: zbuser@usc.edu.
authors.forename: Zorica
authors.initials: Z
authors.lastname: Buser
authors.affiliation: Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, 1520 San Pablo St., Suite 2000 Los Angeles, CA 90033, USA; Department of Orthopaedic Surgery, Renji Hospital, Jiaotong University School of Medicine, No. 160, Pujian Road, Pudong New Area, 200127 Shanghai, China.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Lao
authors.affiliation: Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, 1520 San Pablo St., Suite 2000 Los Angeles, CA 90033, USA; Department of Orthopedic Surgery, China-Japan Union Hospital, Jilin University, 126 XianTai St, Changchun City, Jilin Province 130033, China.
authors.forename: Ruofeng
authors.initials: R
authors.lastname: Yin
authors.affiliation: Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, 1520 San Pablo St., Suite 2000 Los Angeles, CA 90033, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology / Q000503:physiopathology*; D017843:Ligamentum Flavum / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000473:pathology / Q000503:physiopathology*; D011843:Radiculopathy / Q000473:pathology / Q000503:physiopathology*; D016059:Range of Motion, Articular
keywords: Cervical spine; Disc degeneration; Kinematic; Ligamentum flavum bulge (LFB); Magnetic resonance imaging; Spinal cord compression