title: Lumbar spinal fusion with a mineralized collagen matrix and rhBMP-2 in a rabbit model.
abstract: METHODS
  A new mineralized collagen matrix combined with or without growth factor was used for the posterolateral spinal fusion in the rabbit lumbar spine.
  
  
  OBJECTIVE
  The availability of a new osteoconductive matrix with or without recombinant osteoinductive growth factors offers a possible alternative to the use of autogenous bone for grafting indications. This study evaluated the bone-forming activity of the biomimetic matrix: nano-hydroxyapatite/collagen/polylactic acid (nHAC/PLA) combined without or with recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rabbit posterolateral spinal fusion.
  
  
  BACKGROUND
  Many bone grafting materials such as titanium alloy, ceramics, and polymers were used to repair bony defects. However, each has specific disadvantaged. The permanent implantation still has possibility to be eroded in vivo, which is caused by late breakdown and abscess formation. The acidic outcome of polymer biodegradation was also negatively affected in the later-stage results of bone repair. It needed a promising material for an alternative to the use of autogenous bone for grafting indications.
  
  
  METHODS
  Sixty-four rabbits were randomly divided into four groups: autologous iliac crest bone group (ACB), nHAC/PLA composite group (nHAC/PLA), autologous iliac crest bone mixed with nHAC/PLA composite group (ACB + nHAC/PLA), nHAC/PLA composite with recombinant human BMP-2 group (nHAC/PLA + rhBMP-2). The lumbar intertransverse process fusions were assessed by manual palpation, radiographic, histologic, and mechanical strength, and scanning electronic microscopy (SEM) in a 10-week observation.
  
  
  RESULTS
  Optimal formulations of the ACB + nHAC/PLA and nHAC/PLA + rhBMP-2 groups were shown to perform similar to ACB in both the fusion ratio and mechanical strength in the 6 and 10 weeks after surgery. From the microstructure analysis of the samples, there was no negative effect when the compound implanted this composite with autogenous iliac crest, and there was also new bone-like tissue formation implanted this composite without combined rhBMP-2 early at the second week after surgery.
  
  
  CONCLUSIONS
  This study shows the effective results of nHAC/PLA in rabbit posterolateral spinal fusion combined with rhBMP-2. It is an alternative method to autograft by compounding this osteoconductive matrix with growth factors.
authors.affiliation: Biomaterials Laboratory, Department of Materials Science & Engineering, Tsinghua University, Beijing, China.
authors.forename: S S
authors.initials: SS
authors.lastname: Liao
authors.forename: K
authors.initials: K
authors.lastname: Guan
authors.forename: F Z
authors.initials: FZ
authors.lastname: Cui
authors.forename: S S
authors.initials: SS
authors.lastname: Shi
authors.forename: T S
authors.initials: TS
authors.lastname: Sun
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D003094:Collagen / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry; D023421:Models, Animal; D010012:Osteogenesis / Q000187:drug effects; D011817:Rabbits; D011859:Radiography; D011994:Recombinant Proteins / Q000494:pharmacology; D013123:Spinal Fusion / Q000379:methods*; D013997:Time Factors; D016212:Transforming Growth Factor beta
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D008903:Minerals; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D003094:Collagen