EXOGENOUS FIBROBLAST-GROWTH-FACTOR-1 AND FIBROBLAST-GROWTH-FACTOR-2 DO NOT ACCELERATE FRACTURE-HEALING IN THE RABBIT

Both fibroblast growth factors-1 (acidic FGF) and -2 (basic FGF) incre ase the proliferation of osteoblasts and chondrocytes in vitro and FGF -2 stimulates angiogenesis and bone formation in vivo. To test their e ffects on rabbit tibial fracture-healing under stable and unstable mec hanical conditions, 3 mu g of either FGF-1 or FGF-2 was injected aroun d rabbit tibial fractures on day 4 after fracture. Neither growth fact or had a significant effect on either the size of, or the amounts of b one and cartilage in, the 10-day callus irrespective of the mechanical conditions under which the fracture was healing. The 10-day FGF-2-tre ated calluses were, however, more mature than FGF-1-treated calluses b ecause the cartilage was separated from the periosteum by bone and end ochondral ossification had progressed further. In conclusion, the appl ication of FGF-1 or FGF-2 to normally healing fractures of the rabbit tibia does not have a significant effect on the rate of healing.