title: The effect of impaction and a bioceramic coating on bone ingrowth in porous titanium particles.
abstract: OBJECTIVE
  Porous titanium (Ti) particles can be impacted like cancellous allograft bone particles, and may therefore be used as bone substitute in impaction grafting. We evaluated the effect of impaction and of a thin silicated biphasic calcium phosphate coating on osteoconduction by Ti particles.
  
  
  METHODS
  The bone conduction chamber of Aspenberg was used in goats and filled with various groups of coated or uncoated small Ti particles (diameter 1.0-1.4 mm). Impacted allograft bone particles and empty chambers were used in control groups. Fluorochromes were administered at 4, 8, and 12 weeks. Maximum bone ingrowth distance was evaluated by histomorphometric analysis.
  
  
  RESULTS
  Histology of Ti particle graft cylinders showed a dense matrix with narrow inter-particle and intra-particle pores (< 100 μm), occluding the lumen of the bone chamber. Bone ingrowth distances gradually increased with time in all groups. Maximum bone ingrowth distance was higher in originally empty chambers than those with allograft bone particles (p = 0.01) and Ti particles (p < 0.001). Maximum bone ingrowth in allograft bone particles was higher than in all Ti groups (p ≤ 0.001). Impaction reduced osteoconduction and the coating partially compensated for the negative effect of impaction, but these differences were not statistically significant. No osteolytic reactions were found.
  
  
  CONCLUSIONS
  Osteoconduction in the bone conduction chamber was reduced more by the insertion of small Ti particles than by insertion of small allograft bone particles. The osteoconductive potential of porous Ti particles should be studied further with larger-sized particles, which may allow bone ingrowth after impaction through larger inter-particle pores.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopaedics, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands. lucwalschot@gmail.com
authors.forename: Lucas H
authors.initials: LH
authors.lastname: Walschot
authors.forename: Barend W
authors.initials: BW
authors.lastname: Schreurs
authors.forename: Nico
authors.initials: N
authors.lastname: Verdonschot
authors.forename: Pieter
authors.initials: P
authors.lastname: Buma
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D018786:Bone Substitutes; D016025:Bone Transplantation / Q000379:methods / Q000502:physiology; D002516:Ceramics; D020099:Coated Materials, Biocompatible; D005260:Female; D006041:Goats; D020007:Implants, Experimental; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology; D010316:Particle Size; D016062:Porosity; D013977:Tibia / Q000601:surgery; D014025:Titanium; D014184:Transplantation, Homologous
chemical_list: D018786:Bone Substitutes; D020099:Coated Materials, Biocompatible; D014025:Titanium