title: The effect of kyphotic deformity because of vertebral fracture: a finite element analysis of a 10° and 20° wedge-shaped vertebral fracture model.
abstract: BACKGROUND
  Kyphotic deformity associated with vertebral fracture is believed to be a significant risk factor for additional vertebral fractures. However, previously published research is limited.
  
  
  OBJECTIVE
  The purpose of this study was to estimate the biomechanical stresses that kyphotic deformity, with an initial vertebral fracture, place on adjacent vertebrae using three-dimensional finite element (FE) of the spine, head, and ribs.
  
  
  METHODS
  This study is based on the basic science.
  
  
  METHODS
  Total Human Model for Safety, a three-dimensional FE model of the human body, was used and adjusted to represent an elderly osteoporotic woman. The 12th thoracic vertebra (T12), which is a frequent site of osteoporotic vertebral fractures, was transformed to a wedge shape at 0°, 10°, and 20° to create a normal model, a 10° kyphosis model, and a 20° kyphosis model. Additionally, compensated postures were created for the 10° and 20° kyphosis models. Thus, five models were created: (A) a normal model, (B) a 10° kyphosis model, (C) a 20° kyphosis model, (D) a 10° kyphosis model with compensated posture, and (E) a 20° kyphosis model with compensated posture. Compressive principal stresses (CPSs) on T1-L5 in each model were calculated.
  
  
  RESULTS
  The highest CPS value was 7.78 MPa placed on the anterior part of the T10 vertebra in the 20° kyphosis model. In the 20° kyphosis model, the higher CPS values showed bimodal peaks at T6 and T7 in the midthoracic spine and at T10 and T11 in the two superior adjacent vertebrae. The maximum CPS values in the A, B, C, D, and E models at T10 were 3.12, 6.74, 7.78, 6.61, and 5.78 MPa. At T11, they were 1.70, 4.41, 6.45, 4.07, and 4.79 MPa.
  
  
  CONCLUSIONS
  The existence of an initial vertebral fracture at T12 caused an increase in stress on adjacent vertebrae. Higher CPS values showed bimodal peaks in midthoracic vertebrae and in two superior adjacent vertebrae when T12 was transformed to a wedge shape in the 20° kyphosis model.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan. Electronic address: okamoto19780731@yahoo.co.jp.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Murakami
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Demura
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kato
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hayashi
authors.affiliation: Department of Human and Mechanical System Engineering, Faculty of Engineering, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Sakamoto
authors.affiliation: Department of Orthopedic Surgery, Kanazawa Medical University Hospital, 1-1 Uchinadamachi, Kahoku 920-0293, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Kawahara
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000368:Aged; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007738:Kyphosis / Q000209:etiology*; D008953:Models, Anatomic; D058866:Osteoporotic Fractures / Q000150:complications*; D011187:Posture; D016103:Spinal Fractures / Q000150:complications*; D013904:Thoracic Vertebrae / Q000293:injuries*
keywords: Bimodal peaks; Biomechanics; Finite-element analysis; Kyphotic deformity; Osteoporotic vertebral fracture; Whole human model