title: Biological intervertebral disc replacement: an in vivo model and comparison of two surgical techniques to approach the rat caudal disc.
abstract: METHODS
  Prospective randomized animal study.
  
  
  OBJECTIVE
  To determine a surgical technique for reproducible and functional intervertebral disc replacement in an orthotopic animal model.
  
  
  METHODS
  The caudal 3/4 intervertebral disc (IVD) of the rat tail was approached by two surgical techniques: blunt dissection, stripping and retracting (Technique 1) or incising and repairing (Technique 2) the dorsal longitudinal tendons. The intervertebral disc was dissected and removed, and then either discarded or reinserted. Outcome measures were perioperative complications, spontaneous tail movement, 7T MRI (T1- and T2-sequences for measurement of disc space height (DSH) and disc hydration). Microcomputed tomographic imaging (micro CT) was additionally performed postmortem.
  
  
  RESULTS
  No vascular injuries occurred and no systemic or local infections were observed over the course of 1 month. Tail movements were maintained. With tendon retraction (Technique 1) gross loss of DSH occurred with both discectomy and reinsertion. Tendon division (Technique 2) maintained DSH with IVD reinsertion but not without. The DSH was demonstrated on MRI measurement. A new scoring system to assess IVD appearances was described.
  
  
  CONCLUSIONS
  The rat tail model, with a tendon dividing surgical technique, can function as an orthotopic animal model for IVD research. Mechanical stimulation is maintained by preserved tail movements. 7T MRI is a feasible modality for longitudinal monitoring for the rat caudal disc.
authors.affiliation: Brain and Spine Center, Department of Neurosurgery, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Harry
authors.initials: H
authors.lastname: Gebhard
authors.forename: Andrew R
authors.initials: AR
authors.lastname: James
authors.forename: Robby D
authors.initials: RD
authors.lastname: Bowles
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Dyke
authors.forename: Tatianna
authors.initials: T
authors.lastname: Saleh
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Doty
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Bonassar
authors.forename: Roger
authors.initials: R
authors.lastname: Härtl