title: A novel rabbit model of mild, reproducible disc degeneration by an anulus needle puncture: correlation between the degree of disc injury and radiological and histological appearances of disc degeneration.
abstract: METHODS
  An in vivo study to radiographically and histologically assess a new method of induction of disc degeneration. OBJECTIVE.: To establish a reproducible rabbit model of disc degeneration by puncturing the anulus with needles of defined gauges and to compare it to the classic stab model.
  
  
  BACKGROUND
  New treatment approaches to disc degeneration are of great interest. Although animal models for disc degenerative disease exist, the quantitative measurement of disease progression remains difficult. A reproducible, progressive disc degeneration model, which can be induced in a reasonable time frame, is essential for development of new therapeutic interventions.
  
  
  METHODS
  The classic anular stab model and the new needle puncture model were used in the rabbit. For the needle puncture model, 3 different gauges of needle (16G, 18G, and 21G) were used to induce an injury to the disc to a depth of 5 mm. Radiographic and histologic analyses were performed; magnetic resonance images were also assessed in the needle puncture model.
  
  
  RESULTS
  Significant disc space narrowing was observed as early as 2 weeks after stabbing in the classic stab model; there was no further narrowing of the disc space. In the needle puncture model, all needle sizes tested induced a slower and more progressive decrease in disc height than in the classic stab model. The magnetic resonance imaging supported the results of disc height data.
  
  
  CONCLUSIONS
  The needle puncture approach, using 16G to 21G needles, resulted in a reproducible decrease of disc height and magnetic resonance imaging grade. The ease of the procedure and transfer of the methodology will benefit researchers studying disc degeneration.
authors.affiliation: Department of Orthopedic Surgery, Rush Medical College, Chicago, Illinois 60612, USA. kmasuda@rush.edu
authors.forename: Koichi
authors.initials: K
authors.lastname: Masuda
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Aota
authors.forename: Carol
authors.initials: C
authors.lastname: Muehleman
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Imai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Okuma
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Thonar
authors.forename: Gunnar B
authors.initials: GB
authors.lastname: Andersson
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
mesh_terms: D000818:Animals; D001175:Arthrography / Q000592:standards; D004195:Disease Models, Animal; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000592:standards; D009339:Needles; D011817:Rabbits; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014951:Wounds, Stab