THE EFFECT OF RECOMBINANT HUMAN BONE MORPHOGENETIC PROTEIN-2 ON THE INTEGRATION OF POROUS HYDROXYAPATITE IMPLANTS WITH BONE

To determine if recombinant human bone morphogenetic protein-2 (rhBMP- 2) can be adsorbed onto porous ceramic hydroxyapatite (HA) and promote the integration of HA to host bone, 54 subperiosteal pockets were cre ated on the skulls of 19 adult Pasteurella-free white rabbits. Fourtee n HA implants were saturated with saline and placed in subperiosteal p ockets (control), 22 HA implants were saturated with saline and placed into subperiosteal pockets after burring 1-2 mm of calvarium to expos e bleeding cancellous bone, and 18 HA implants were saturated with rhB MP-2 and placed into subperiosteal pockets. The animals were sacrifice d at 1 month with examination to determine implant mobility. Histology was used to determine the amount of bone growth into the implant. Of the 14 control sites, 10 implants were found to be freely mobile, five demonstrated host bone resorption, and only one exhibited bone growth into the implant. Of the 22 burred sites, eight were freely mobile an d 10 demonstrated bone growth into the implant (p = 0.04). Of the 18 r hBMP-2 sites, only two were freely mobile, none demonstrated host bone resorption, and 16 exhibited bone growth into the implant (p = 0.0000 2). This study supports the use of porous ceramic HA as a biocompatibl e, osteoconductive implant material for use in craniomaxillofacial aug mentation and reconstruction. It also provides evidence that rhBMP-2 e nhances osseointegration, thereby fixing the implant in position again st the host-bone interface. Ln the clinical setting, osseous fixation of the implant should aid in preventing displacement, minimizing host bone resorption, and decreasing the incidence of extrusion. (C) 1998 J ohn Wiley & Sons, Inc.