title: Autograft versus allograft with or without demineralized bone matrix in posterolateral lumbar fusion in rabbits. Laboratory investigation.
abstract: OBJECTIVE
  Posterolateral spinal fusions are performed to treat different spinal disorders. Autograft continues to be the gold standard; it is, however, associated with donor site morbidity and limited sources. Allograft has been used, but has been reported to result in lower fusion rates. Demineralized bone matrix (DBM) has also been used and reportedly increases the fusion rate in a variety of critical defect models. Different forms of DBM are available, not all have been independently studied. To evaluate the effect of a xenogenic DBM added to allograft on the fusion rate of posterolateral lumbar spine arthrodesis the authors designed an experimental study comparing posterolateral fusion rate using autograft, allograft, and allograft plus a xenogenic DBM in a validated animal model.
  
  
  METHODS
  A bilateral, 1-level (L4-5) intertransverse process fusion was performed in 45 male New Zealand rabbits. Iliac crest bone graft was harvested bilaterally from each rabbit. The rabbits were randomly assigned to 3 groups: Group I, Autograft, 15 rabbits; Group II, Allograft, 15 rabbits; and Group III, Allograft plus DBM in a paste form (Dynagraft). The animals were killed 8 weeks after surgery. Fusion was assessed radiographically and by manual palpation by 2 independent observers. The results were analyzed using the Fisher exact test and chi-square test.
  
  
  RESULTS
  The fusion rate was 46.6% (7 of 15 rabbits) in the autograft group, 33.3% (5 of 15 rabbits) in the allograft group, and 33.3% (5 of 15 rabbits) in the allograft plus DBM group (p > 0.05).
  
  
  CONCLUSIONS
  Autograft produced a higher fusion rate than allograft in this spinal fusion rabbit model, but the difference was not statistically significant. Allograft plus xenogenic DBM showed the same fusion rate as allograft alone.
authors.affiliation: Department of Orthopaedic Surgery, Pontificia Universidad Catolica de Chile, Santiago, Chile. jurrutia@med.puc.cl
authors.forename: Julio
authors.initials: J
authors.lastname: Urrutia
authors.forename: Nicolas
authors.initials: N
authors.lastname: Thumm
authors.forename: Daniel
authors.initials: D
authors.lastname: Apablaza
authors.forename: Felipe
authors.initials: F
authors.lastname: Pizarro
authors.forename: Alejandro
authors.initials: A
authors.lastname: Zylberberg
authors.forename: Felipe
authors.initials: F
authors.lastname: Quezada
mesh_terms: D000818:Animals; D001857:Bone Matrix / Q000637:transplantation*; D016025:Bone Transplantation; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D011817:Rabbits; D013123:Spinal Fusion / Q000379:methods*; D014182:Transplantation, Autologous; D014184:Transplantation, Homologous