LOCAL INJECTION OF TGF-BETA INCREASES THE STRENGTH OF TIBIAL FRACTURES IN THE RAT

The effect of Transforming Growth Factor beta (TGF-beta) administered locally around the fracture line of healing rat tibial fractures was i nvestigated after 40 days of healing. TGF-beta in a dose of 4 ng or 40 ng was injected every second day during the healing period. The stren gth, stiffness, energy absorption and deflection of the fractures were measured in a materials-testing machine. Compared with placebo-treate d animals, the ultimate load of the fractures increased in the group i njected with 40 ng of TGF-beta, but not in those injected with 4 ng. T GF-beta induced a dose-dependent increase in the cross-sectional area of the callus and bone at the fracture line. Consequently, local treat ment of fractures with TGF-beta increases the callus formation and str ength. The energy absorption and deflection capacities of the healing fractures are preserved.