The effect of transforming growth factor-beta1, released from a bioabsorbable self-reinforced polylactide pin, on a bone defect

Transforming growth factor-beta 1 (TGF-beta1)is a polypeptide growth factor which has been shown to increase bone formation in experimental studies. In this study it was combined to a bioabsorbable self-reinforced poly-LD-lactic acid fracture fixation pin. To assess the effect of TGF-beta1 on the healing of a bone defect, the pins were implanted in the rat distal femur next to a bone defect filled with a viscose cellulose sponge. The pins used in the study group (13 rats) contained 50 microg of TGF-beta1, whereas in the control group of nine rats an identical pin without the growth factor was used. In the histologic examination at 1, 3 and 6 weeks no difference was detected in the amount of bone inside the viscose cellulose sponge between the rats treated with TGF-beta1 and those with no added growth factor. At 3 weeks there was more fibroblast-rich mesenchymal tissue inside the viscose cellulose sponge in the rats treated with TGF-beta1. In the radiographic examination at 3 weeks there was an increase in the amount of new periosteal bone on the bone defect in the TGF-beta1-treated rats.