title: Unconstrained testing of spine with bi-axial universal testing machine.
abstract: BACKGROUND
  In-vitro biomechanical assessment of the spine reveals significant information on the mechanics of spinal disorders, treatment methods, and surgical implants. Specialized devices for the evaluation of spine biomechanics have thus become popular. However, these devices might not be affordable for all research groups.
  
  
  OBJECTIVE
  The purpose of this study was to describe an apparatus to be attached to a standard bi-axial universal testing machine that would make unconstrained testing of the spine possible.
  
  
  METHODS
  A technical note on the definition of a spinal testing fixture with validation.
  
  
  METHODS
  Intact lumbosacral spines (T12-S1) were tested in sagittal and lateral bending and axial rotation. Three-dimensional interlevel rotations at each level (L1-4) were analyzed.
  
  
  RESULTS
  By comparison with the literature, we found that the new fixture was able to successfully produce reasonable relative rotation values for the lumbar spine.
  
  
  CONCLUSIONS
  We demonstrated that the low cost fixture allowed unconstrained (six degree of freedom, 6 DOF) testing of fresh-frozen cadaveric lumbar spine.
authors.affiliation: Orthopedic Biomechanics Laboratory, Department of Orthopedics, Loma Linda University, United States. Electronic address: sinceoglu@llu.edu.
authors.forename: Serkan
authors.initials: S
authors.lastname: Inceoğlu
authors.affiliation: School of Medicine, Loma Linda University, United States.
authors.forename: Justin
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Medicine, Loma Linda University, United States.
authors.forename: Hayden
authors.initials: H
authors.lastname: Cale
authors.affiliation: School of Medicine, Loma Linda University, United States.
authors.forename: Bjorn
authors.initials: B
authors.lastname: Harboldt
authors.affiliation: Spine Section, Department of Orthopedics, Loma Linda University, United States.
authors.forename: Wayne K
authors.initials: WK
authors.lastname: Cheng
mesh_terms: D004738:Engineering; D006801:Humans; D008159:Lumbar Vertebrae; D008422:Materials Testing / Q000191:economics / Q000295:instrumentation / Q000379:methods*
keywords: 6 degree of freedom testing; Fixture; Flexibility test; Kinematics; Range of motion; Spine