TRANSFORMING GROWTH-FACTOR-BETA-1 STIMULATES BONE ONGROWTH TO WEIGHT-LOADED TRICALCIUM PHOSPHATE COATED IMPLANTS - AN EXPERIMENTAL-STUDY INDOGS

Bone growth into cementless prosthetic components is compromised by os teoporosis, by any gap between the implant and the bone, by micromotio n, and after the revision of failed prostheses, Recombinant human tran sforming growth factor-beta 1 (rhTGF-beta 1) has recently been shown t o be a potent stimulator of bone healing and bone formation in various models in vivo, We have investigated the potential of rhTGF-beta 1, a dsorbed on to weight-loaded tricalcium phosphate (TCP) coated implants , to enhance bone ongrowth and mechanical fixation, We inserted cylind rical grit-blasted titanium alloy implants bilaterally into the weight -bearing part of the medial femoral condyles of ten skeletally mature dogs, The implants were mounted on special devices which ensured stabl e weight-loading during each gait cycle, All implants were initially s urrounded by a 0.75 mm gap and were coated with TCP ceramic, Each anim al received two implants, one with 0.3 mu g rhTGF-beta 1 adsorbed on t he ceramic surface and the other without growth factor, Histological a nalysis showed that bone ongrowth was significantly increased from 22 +/- 5.6% bone-implant contact in the control group to 36 +/- 2.9% in t he rhTGF-beta 1 stimulated group, an increase of 59%, The volume of bo ne in the gap was increased by 16% in rhTGF-beta 1-stimulated TCP-coat ed implants, but this difference was not significant, Mechanical push- out tests showed no difference in fixation of the implant between the two groups. Our study suggests that rhTGF-beta 1 adsorbed on TCP-ceram ic-coated implants can enhance bone ongrowth.