title: Evaluation of a novel silicate substituted hydroxyapatite bone graft substitute in a rabbit posterolateral fusion model.
abstract: METHODS
  Randomized, controlled study in a laboratory setting. Blinded observations/assessment of study outcomes.
  
  
  OBJECTIVE
  The purpose of this study is to determine the performance characteristics of a novel silicate-substituted hydroxyapatite bone graft substitute (BGS), SiCaP EP (Baxter Healthcare/ ApaTech, Elstree, UK), in a stand-alone mode, a stand-alone with bone marrow aspirate (BMA) mode, and an extender mode with iliac crest autograft (ICBG) in a rabbit posterolateral spine fusion model. The investigational BGS is compared to a standard iliac crest autograft (ICBG) control.
  
  
  BACKGROUND
  The rabbit posterolateral fusion model is an established environment for testing of fusion efficacy. It offers the opportunity to obtain radiographic, histological, and biomechanical data on novel bone graft substitutes.
  
  
  METHODS
  One hundred and twenty rabbits were entered into the study with 116 used for analysis. Bilateral posterolateral lumbar intertransverse fusions were performed at L5-L6. The lateral two thirds of the transverse processes were decorti cated and covered with graft material in the following five groups: ICBG, SiCaP EP stand-alone, SiCaP EP with BMA (1:0.5 by volume), and SiCaP EP with ICBG (1:3 by volume). Rabbits were necropsied at 4, 8, and 12-week time points and fusion rate, quantity, and quality was evaluated based on manual palpation, mechanical stiffness testing, pqCT, and histological assessment.
  
  
  RESULTS
  SiCaP EP, ICBG+SiCaP EP (3:1), and SiCaP EP+BMA (1:0.5) compare favorably to iliac crest autologous bone by multiple metrics in this rabbit posterolateral fusion model. Fusion efficacy via manual palpation and mechanical stiffness testing metrics indicate that all SiCaP EP groups had similar group-to-group performance, and were not significantly different than the ICBG control at each time period evaluated.
  
  
  CONCLUSIONS
  In this commonly used rabbit posterolateral fusion model, SiCaP EP utilized as a stand-alone, as a stand-alone with BMA, and as an autograft (ICBG) extender produces results that are clinically and radiographically similar to ICBG.
authors.affiliation: The University of Iowa, Department of Orthopaedics and Rehabilitation, Iowa City, Iowa; The Bone Healing Research Laboratory; The Iowa Spine Research Center .
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Fredericks
authors.forename: Emily B
authors.initials: EB
authors.lastname: Petersen
authors.forename: Nikhil
authors.initials: N
authors.lastname: Sahai
authors.forename: Katherine Gibson N
authors.initials: KG
authors.lastname: Corley
authors.forename: Nicole
authors.initials: N
authors.lastname: DeVries
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Grosland
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Smucker
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000627:therapeutic use*; D016025:Bone Transplantation / Q000379:methods*; D017886:Durapatite / Q000627:therapeutic use*; D007085:Ilium / Q000637:transplantation*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008422:Materials Testing; D023421:Models, Animal; D011817:Rabbits; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D017886:Durapatite
references.citation: Iowa Orthop J. 2012;32:61-8
references.pmid: 23576923
references.citation: J Biomed Mater Res B Appl Biomater. 2011 May;97(2):245-54
references.pmid: 21384544
references.citation: Acta Biomater. 2012 Jul;8(7):2788-94
references.pmid: 22475784
references.citation: Spine (Phila Pa 1976). 2007 Jan 15;32(2):174-81
references.pmid: 17224811
references.citation: J Biomed Mater Res A. 2013 Jan;101(1):13-22
references.pmid: 22733430
references.citation: J Biomed Mater Res A. 2012 Jun;100(6):1550-5
references.pmid: 22419568
references.citation: Spine (Phila Pa 1976). 2012 May 20;37(12):1017-21
references.pmid: 22166929
references.citation: Biomater Med Devices Artif Organs. 1979;7(2):291-7
references.pmid: 465631
references.citation: Biomaterials. 2006 Oct;27(29):5014-26
references.pmid: 16790272
references.citation: Eur Spine J. 2009 Nov;18(11):1610-20
references.pmid: 19475437
references.citation: J Bone Joint Surg Am. 2011 Dec 7;93(23):2219-26
references.pmid: 22159858
references.citation: Spine (Phila Pa 1976). 2008 May 20;33(12):1324-9
references.pmid: 18496344