title: Comparison of animals used in disc research to human lumbar disc geometry.
abstract: METHODS
  Measurement and normalization of disc geometry parameters for several animal models used in disc research.
  
  
  OBJECTIVE
  To compare normalized values of disc geometry to the human disc geometry to aid in the selection and interpretation of animal model studies.
  
  
  BACKGROUND
  Animal models are widely used to study intervertebral disc degeneration and to evaluate disc treatment methods because of the availability of the tissue, the decreased variability between subjects compared with humans, and the feasibility to perform in vivo experiments. There is a general lack of comparative data with respect to the human disc analog for animal models.
  
  
  METHODS
  The disc height, lateral width, AP width, area, and the nucleus pulposus lateral width, AP width, area, and centroid offset were all measured and normalized by 2 scaling factors, lateral width and disc area, for comparison to human.
  
  
  RESULTS
  The species studied were ranked according to the average percent deviation of the normalized disc height, AP width and nucleus pulposus area from human geometry as: mouse lumbar (12%), rat lumbar (15%), mouse tail (18%), baboon (19%), bovine tail (22%), rabbit (26%), sheep (31%), and rat tail (46%).
  
  
  CONCLUSIONS
  This paper provides a reference to compare disc geometries of experimental animal models to the human lumbar disc, to aid both in interpretation of and in planning for experimental disc research, and to provide normalized disc geometry parameters for computational models.
authors.affiliation: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6081, USA.
authors.forename: Grace D
authors.initials: GD
authors.lastname: O'Connell
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Vresilovic
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Elliott
mesh_terms: D000328:Adult; D000818:Animals; D002417:Cattle; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D051379:Mice; D023421:Models, Animal; D010215:Papio; D011817:Rabbits; D011859:Radiography; D051381:Rats; D012107:Research Design; D012756:Sheep; D013045:Species Specificity; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000473:pathology