title: Beta-tricalcium phosphate as a substitute for autograft in interbody fusion cages in the canine lumbar spine.
abstract: OBJECTIVE
  An interbody fusion cage has been introduced for cervical anterior interbody fusion. Autogenetic bone is packed into the cage to increase the rate of union between adjacent vertebral bodies. Thus, donor site-related complications can still occur. In this study a synthetic ceramic, beta-tricalcium phosphate (TCP), was examined as a substitute for autograft bone in a canine lumbar spine model.
  
  
  METHODS
  In 12 dogs L-1 to L-4 vertebrae were exposed via a posterolateral approach, and discectomy and placement of interbody fusion cages were performed at two intervertebral disc spaces. One cage was filled with autograft (Group A) and the other with TCP (Group B). The lumbar spine was excised at 16 weeks postsurgery, and biomechanical, microradiographic, and histological examinations were performed. Both the microradiographic and histological examinations revealed that fusion occurred in five (41.7%) of 12 operations performed in Group A and in six (50%) of 12 operations performed in Group B. The mean percentage of trabecular bone area in the cages was 54.6% in Group A and 53.8% in Group B. There were no significant intergroup differences in functional unit stiffness.
  
  
  CONCLUSIONS
  Good histological and biomechanical results were obtained for TCP-filled interbody fusion cages. The results were comparable with those obtained using autograft-filled cages, suggesting that there is no need to harvest iliac bone or to use allo- or xenografts to increase the interlocking strength between the cage and vertebral bone to achieve anterior cervical interbody fusion.
authors.affiliation: Department of Neurosurgery, Mie University School of Medicine, Tsu, Japan.
authors.forename: Takashiro
authors.initials: T
authors.lastname: Ohyama
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Kubo
authors.forename: Hiroo
authors.initials: H
authors.lastname: Iwata
authors.forename: Waro
authors.initials: W
authors.lastname: Taki
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D016025:Bone Transplantation; D002130:Calcium Phosphates / Q000627:therapeutic use*; D017586:Diskectomy; D004285:Dogs; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D014182:Transplantation, Autologous
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; C018392:tricalcium phosphate