title: Biomechanical study of cervical flexion myelopathy using a three-dimensional finite element method.
abstract: OBJECTIVE
  The goal of this study was to perform a biomechanical study of cervical flexion myelopathy (CFM) using a finite element method.
  
  
  METHODS
  A 3D finite element model of the spinal cord was established consisting of gray matter, white matter, and pia mater. After the application of semi-static compression, the model underwent anterior flexion to simulate CFM. The flexion angles used were 5 degrees and 10 degrees , and stress distributions inside the spinal cord were then evaluated.
  
  
  RESULTS
  Stresses on the spinal cord were very low under semi-static compression but increased after 5 degrees of flexion was applied. Stresses were concentrated in the gray matter, especially the anterior and posterior horns. The stresses became much higher after application of 10 degrees of flexion and were observed in the gray matter, posterior funiculus, and a portion of the lateral funiculus.
  
  
  CONCLUSIONS
  The 5 degrees model was considered to represent the mild type of CFM. This type corresponds to the cases described in the original report by Hirayama and colleagues. The main symptom of this type of CFM is muscle atrophy and weakness caused by the lesion of the anterior horn. The 10 degrees model was considered to represent a severe type of CFM and was associated with lesions in the posterior fand lateral funiculi. This type of CFM corresponds to the more recently reported clinical cases with combined long tract signs and sensory disturbance.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan. kato-yo@yamaguchi-u.ac.jp
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kato
authors.forename: Hideo
authors.initials: H
authors.lastname: Kataoka
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ichihara
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Imajo
authors.forename: Takanori
authors.initials: T
authors.lastname: Kojima
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kawano
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hamanaka
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yaji
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Taguchi
mesh_terms: D000465:Algorithms; D000870:Anterior Horn Cells / Q000503:physiopathology; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000503:physiopathology*; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008959:Models, Neurological; D010841:Pia Mater / Q000503:physiopathology; D020671:Posterior Horn Cells / Q000503:physiopathology; D013116:Spinal Cord / Q000503:physiopathology; D013117:Spinal Cord Compression / Q000209:etiology*; D013122:Spinal Diseases / Q000150:complications*; D013314:Stress, Mechanical