DEMINERALIZED BONE-MATRIX IN THE STABILIZATION OF POROUS-COATED IMPLANTS IN BONE DEFECTS IN RABBITS

Three types of grafts were investigated in rabbits to measure fixation strength of bony ingrowth into porous-coated titanium alloy implants. Autogeneic iliac crest bone (ABG), allogeneic demineralized bone matr ix (DBM), and DBM augmented with fibrin glue (DBM + FG) grafts were co mpared with a press-fit implant control group. Initially, the ABG grou p required eight weeks and the DBM and DBM + FG groups 12 weeks to ach ieve fixation strength similar to that of the press-fit group at four weeks. Strength increased with time and at 16 weeks reached 83 kg in t he ABG group, 71 kg in the DBM group, and 79 kg in the DBM + FG group, compared with 86 kg for the press-fit group. The ratio of the DBM and the DBM + FG group push-out forces to the ABG push-out force improved from 40% at four weeks to more than 80% at 16 weeks. Histologic analy sis of bone ingrowth showed that at 12 weeks, bony ingrowth accounted for 21%, 22%, 16%, and 32%, of the porous area in the ABG, DBM, DBM FG, and press-fit groups, respectively. After eight weeks, there was n o statistical difference between DBM, DBM + FG, and ABG grafts in eith er strength or bony ingrowth. The results demonstrate that over long p eriods, DBM grafts provide fixation stability comparable with that of autogeneic bone graft.