Abstract: Objective To explore the mechanism of platelet-derived growth factor(PDGF) and vascular endothelial growth factor(VEGF) enhanced osteogenesis on SDrats fracture healing after cerebral trauma by investigating the distinct expressions of PDGFand VEGFin fracture only and in fracture with brain injury.Theory basis was afforded for the treatment of refractoriness fracture for clinical selectivity.Methods Two hundred and four rats were divided into four groups randomly: group A,negative control(n=12);group B,cerebral trauma group(n=56);group C,fracture group(n=68);and group Dfracture with cerebral trauma group(n=68).The rat models of fracture and cerebral trauma were established.8 rats in each of group B,Cand Dwere put to death in the first day,fourth day,first week,second week,third week,fourth week and fifth week after the operation.Osteotylus samples were obtained about one centimeter away from broken ends of fractured bone for immunohistochemistry staining.The rats which were put to death in the fourth and fifth week were examined with X-rays to observe the reparative process.And then,12 rats of group Cand Dwere put to death at the sixth week.They were examined with X-rays and taken the whole left radial bone for biomechanical experiment.Results ① X-rays: group C: In the fourth and fifth week,there were some existing callus and fracture lines were clear.In the sixth week,the fracture lines were not clear but still can be seen.group D: In the fourth week,fracture lines were clear.In the fifth week,the fracture lines were not clear.And in the sixth week,the fracture lines were disappeared.② Biomechanical experiment: In the sixth week,the maximum load that radial bones in group Aand Dcan be accepted were nearly the same.When comparing to group C,there was statistical significance(P﹤0.01).③ Immunohistochemistry staining image analysis: PDGF: the expression in group Cstarted to appear in the first day and rose to the peak about in the second week.The expression of PDGFin group Dstarted to appear in the first day,but the first week it was close to the peak,reaching it by the second week in the first day,fourth day and the first week,there was statistical significance between group Cand group D(P<0.01).VEGF: the expressions of group Cappeared in the first week and rose to the peak by about the third week.The expression of VEGFin group Dstarted to appear in the fourth day,reached the peak about the third week.In the fourth day,the first week and the second week,there was statistical significance between group Cand D(P<0.01).Conclusions ① According to the results of the X-ray and biomechanics experiment,the fracture healing speed in group Dis faster than group C.② According to the results of immunohistochemistry staining image analysis,the persistence time of the expression of PDGFand VEGFof group Dis longer than group C.And the crest-time of group Dcomes earlier than group C.③ The acceleration of fracture healing after cerebral trauma may be relevant to longer persistence time and ahead of schedule in expression crest-time of PDGF and VEGF.

Key words: rats, cerebral trauma, fracture, PDGF, VEGF