title: Efficacy of Bone Source™ and Cementek™ in comparison with Endobon™ in critical size metaphyseal defects, using a minipig model.
abstract: BACKGROUND
  To examine and compare biocompatibility, osteocompatibility, rate of resorption, and remodelling dynamics of 2 calcium phosphate cements in comparison with a well-established hydroxyapatite ceramic.
  
  
  METHODS
  In a randomised fashion, Bone Source™, Cementek™, and Endobon™ were implanted bilaterally into the proximal metaphyseal tibiae of 35 Göttinger minipigs in a direct right vs. left intra-individual comparison. Fluorescent labelling was used. Histological and morphometric evaluations were carried out at 6, 12, and 52 weeks.
  
  
  RESULTS
  All bone substitutes showed good biocompatibility, bioactivity, and osteoconductivity. Endobon™ was not degraded over the follow-up period. Cementek™ was degraded constantly and significantly over the time intervals, whereas Bone Source™ was degraded mainly from the 6 week to 12 week interval. After 52 weeks, a significant difference of residual material within the defect zone was detected between all substitutes, with the highest resorption rate for Cementek™. Bone Source™ was least degraded. Defects filled with Endobon™ were characterised by a significantly continuous bony ingrowth over the time intervals. Bone formation within the defects filled with Cementek™ and Bone Source™ showed significant peaks 12 weeks after implantation. After 52 weeks, a significant difference in the amount of new bone within the defect area was detected, with the highest levels for Endobon™, followed by Cementek™.
  
  
  CONCLUSIONS
  After 1 year a restitution ad integrum could not be observed in any treatment group. The ceramic Endobon™ showed the expected response histologically. Based on its porosity it excelled in osteoconductivity. Concerning the calcium phosphate cements, a thorough osseous incorporation seemed to inhibit further degradation of both bone substitute materials.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Hospital Bad Reichenhall, Bad Reichenhall, Germany. christianspies1@gmx.net
authors.forename: Christian K G
authors.initials: CK
authors.lastname: Spies
authors.forename: Stefan
authors.initials: S
authors.lastname: Schnürer
authors.forename: Tobias
authors.initials: T
authors.lastname: Gotterbarm
authors.forename: Steffen J
authors.initials: SJ
authors.lastname: Breusch
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D001862:Bone Resorption / Q000628:therapy*; D018786:Bone Substitutes / Q000627:therapeutic use*; D001842:Bone and Bones / Q000293:injuries*; D005500:Follow-Up Studies; D006882:Hydroxyapatites / Q000627:therapeutic use*; D023421:Models, Animal; D013552:Swine; D013556:Swine, Miniature
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D006882:Hydroxyapatites; C475044:hydroxyapatite cement; C104266:endobon