EFFECT OF PLATELET-DERIVED GROWTH-FACTOR ON TIBIAL OSTEOTOMIES IN RABBITS

The effect of exogenous platelet-derived growth factor (PDGF) BB on bo ne healing was tested in a pilot study using a unilateral tibial osteo tomy in rabbits. Each osteotomy was injected with collagen or collagen containing 80 mu g of PDGF. At 28 days, both tibiae from each rabbit were harvested and subjected to three-point bending to failure. The ef fect upon bone healing was tested by comparing the healing rates of PD GF-treated and -nontreated osteotomies with their respective normal co ntralateral bones. Three animals died before 28 days. The remaining 6 experimental and 5 control animals were available for assessment. Radi ographically, at 2 weeks and 4 weeks, there was a clear increase in ca llus density and volume around the PDGF-treated osteotomies compared w ith the control rabbits' osteotomies. Osteotomies treated with PDGF we re not statistically different in strength from their nonoperated cont ralateral bones. In the control group, however, the osteotomies were s tatistically weaker than their nonoperated (contralateral) bones. Micr oscopically, it was generally observed that PDGF-treated tibiae displa yed a more florid and advanced state of osteogenic differentiation, bo th endosteally and periosteally, than the control osteotomies. Radiogr aphic, mechanical, and histopathological data suggest that exogenous P DGF has a stimulatory effect on fracture healing.