title: Development of a scoliotic spine model for biomechanical in vitro studies.
abstract: BACKGROUND
  In vitro experiments are important to compare surgical treatments. Especially new implants need preclinical evaluation. However, in vitro experiments with scoliotic specimens are impossible because they are not available. The purpose of this study was to develop an in vitro scoliosis model with cadaveric calf spine specimens, which may serve as a surrogate for human scoliotic spines.
  
  
  METHODS
  Six cadaveric calf spine specimens (T8-L6) were modified in three different steps to create a thoracolumbar scoliosis, convex to the right. First, all intervertebral discs received a nucleotomy. In the second step the cavity was filled with silicone. The silicone hardened in a bend position to obtain an asymmetrical nucleus. Finally, a wedge profile of the vertebral bodies was achieved by unilateral horizontal cuts (T9-L5), followed by spreading and fixation. Flexibility tests in a spine tester were performed in all motion planes with the original spine and after the different steps during the creation of the model.
  
  
  RESULTS
  A Cobb angle >40° in the frontal plane could be achieved. Additionally, the vertebrae showed an axial rotation to the convex side. The range of motion increased due to the nucleotomy, decreased slightly after replacement with silicone, and decreased below the values of the intact spine after producing the wedge shape of the vertebrae. In each loading direction there was no significant asymmetry in the motion behavior.
  
  
  CONCLUSIONS
  This study suggests a method to modify a straight spine specimen into a scoliotic one, which can be used for biomechanical in vitro experiments.
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research Ulm, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany. Electronic address: hans-joachim.wilke@uni-ulm.de.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Wilke
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research Ulm, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Mathes
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research Ulm, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Midderhoff
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research Ulm, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Graf
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000601:surgery; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D008953:Models, Anatomic; D023421:Models, Animal; D016059:Range of Motion, Articular; D012399:Rotation; D012600:Scoliosis / Q000503:physiopathology*; D013131:Spine / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000503:physiopathology / Q000601:surgery*
keywords: Biomechanical test; Calf spine; In vitro test; Scoliosis model