title: The state of lumbar fusion extenders.
abstract: METHODS
  Review of literature.
  
  
  OBJECTIVE
  To evaluate the available literature supporting the use of lumbar fusion extenders in clinical practice.
  
  
  BACKGROUND
  Because of the morbidity associated with the harvest of autologous iliac crest bone grafts, the search for lumber fusion extenders and replacements has accelerated. Many formulations of lumbar fusion extenders have been developed, and it is essential to evaluate clinical literature and available outcome metrics of these extenders.
  
  
  METHODS
  A review of English-language literature was performed between 1990 and January of 2010 for all literature presenting clinical outcomes of lumbar fusion extenders. After controlling for inclusion and exclusion criteria and assigning levels of evidence, 19 clinical studies were fully reviewed including those for demineralized bone matrix, recombinant human bone morphogenetic protein 2 (rhBMP-2), β-tricalcium phosphate, and calcium sulfate.
  
  
  RESULTS
  The most extensively studied of the lumbar fusion extenders is β-tricalcium phosphate, especially with regard to its use in adolescent scoliosis correction. The use of rhBMP-2 and demineralized bone matrix is supported only by two and three clinical studies, respectively. Calcium sulfate and other miscellaneous extenders are not conclusively or consistently supported by available clinical studies.
  
  
  CONCLUSIONS
  Calcium phosphate is the most supported of the lumbar fusion extenders. rhBMP-2 and demineralized bone matrix are supported by smaller bodies of evidence. These formulations are supported by these initial studies but in some cases need to be better examined with regard to side effect profiles.
authors.affiliation: Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA.
authors.forename: Kalil G
authors.initials: KG
authors.lastname: Abdullah
authors.forename: Michael P
authors.initials: MP
authors.lastname: Steinmetz
authors.forename: Edward C
authors.initials: EC
authors.lastname: Benzel
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mroz
mesh_terms: D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use; D018786:Bone Substitutes / Q000627:therapeutic use*; D016025:Bone Transplantation; D002130:Calcium Phosphates / Q000627:therapeutic use; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D011994:Recombinant Proteins / Q000627:therapeutic use; D013123:Spinal Fusion / Q000379:methods*; D055009:Spondylosis / Q000601:surgery*; D016212:Transforming Growth Factor beta / Q000627:therapeutic use
chemical_list: D055396:Bone Morphogenetic Protein 2; D018786:Bone Substitutes; D002130:Calcium Phosphates; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C485817:beta-tricalcium phosphate; C499469:recombinant human bone morphogenetic protein-2