The effect of pretreating morselized allograft bone with rhBMP-2 and/or pamidronate on the fixation of porous Ti and HA-coated implants.
BMPs stimulate new bone formation, but may also accelerate bone resorption. We added rhBMP-2 and pamidronate to morselized bone allograft packed around uncemented HA-coated and non-coated porous Ti implants in sixteen dogs. Each dog received four implants where the allograft was added (1) nothing, (2) BMP, (3) BP, and (4) BMP+BP. After four weeks, the untreated control implants had better mechanical fixation than all other treatment groups. The rhBMP-2-treated group had abundant formation of new bone on and around the implant. However, almost all allografts were resorbed, rendering the implant mechanically unstable. In the pamidronate-treated group the allograft was preserved, but the implants were covered by fibrous tissue and there was almost no new bone formation. This was also the case for the combined BMP+BP group, although fibrous tissue was absent on these implants. The HA-coated implants had more than twice as good mechanical fixation and improved osseointegration compared to the corresponding Ti implants. RhBMP-2 raised the total metabolic turnover of bone within the allograft with a net negative result on implant fixation. Pamidronate virtually blocked bone metabolism, also when combined with rhBMP-2. The results warrant a conservative approach and emphasize the importance of identifying a therapeutic window for these substances prior to clinical use.
Baas
Jorgen
J
Orthopaedic Research Laboratory, Aarhus University Hospital, Norrebrogade 44, Building 1a, 8000 Aarhus C, Denmark. baas@ki.au.dk
Elmengaard
Brian
B
Jensen
Thomas B
TB
Jakobsen
Thomas
T
Andersen
Niels T
NT
Soballe
Kjeld
K
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D016025:Bone Transplantation; D004164:Diphosphonates / Q000008:administration & dosage*; D004285:Dogs; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D000077268:Pamidronate; D019736:Prostheses and Implants; D011994:Recombinant Proteins / Q000008:administration & dosage*; D014025:Titanium / Q000737:chemistry*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*; D014184:Transplantation, Homologous
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004164:Diphosphonates; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D006820:Hyaluronic Acid; D014025:Titanium; D000077268:Pamidronate