Effect Of Cerebal Injury On Expression Of Nerve Growth Factor In Bony Callus Of Fractured Femoral Bone

ObjectiveInvestigate the expression change of nerve growth factor (NGF) in bony callus after fracture of the femur in rats with cerebral injury to identify the effect of nerve growth factor (NGF) in the process of union of fracture. And further investigate the effect and mechanism of central nerve system injury in the union of fracture.Methods60 adult healthy male SD rats were randomly divided into femur fracture group (group A, n = 30) and tibia fracture with cerebral injury group ( group B, n = 30) . Group A were only cut off the same side femoral bone and fixed by Kirschn- er wire, group B were established by free weight dropping and knocking method. Then randomly selected 6 rats respectively from each group at five time points (1 day, 4 days, 1 week, 2 weeks and 3 weeks). Observe osteoplastic situation in every time point via cell morphology observation and expressions of NGF in bony callus were determined by immunohistochemistry stain.Results1 Gross anatomy observation showed the speed of union of fracture in group B were faster than in group A.2 By histomorphology observation under microscope:I group A: The animal models in simple fracture group appeared a typical healing course, the periosteal proliferation process was light, Only a little bony callus. Both membrane bone formation and enchondral bone formation existed in this process. The periost began to thicken on the 4th day, the quantity of cartilage cell and fibroblast in periost increased gradually. Typical bone trabecula emerged on the 14th day. II Group B: the fracture appeared blood tumor and inflammatory reaction. Periost obviously thickened on the 2nd day, it began to emerge cartilage cell in periost on the 4 th day. There was a quantity of fibrous callus and collagenoblas. On the 7 th day, the cartilage cell in fibrous callus and Subperiosteum began to increase, some of them coalesced together, endochondral bone formation were less. On the 14 th day, there were still a great quantity of fibrous callus and cartilage bone callus, a small quantity of parce woven bone emerged beside the cartilage cells, the cartilage in ex-subperiosteum were still not completely changed to woven bone.3 By means of immunohistochemistry stain: In group A: NGF expressed weakly in fibroblast and chondroblasts in callus. The masculine cell population have not obviously change in the 21 days. In group B: NGF expressed in fibroblast and chondroblasts in callus were enhanced on the 4 th day, The masculine cell population increased obviously on the 7 th day, and bone formation with NGF highest expressed on the 14 th day. We found masc bone cell number in group B is significantly bigger than in group A on the 4 th day,the 1st week,the 2nd week and the 3rd week(P<0.05).ConclusionThe experiment has showed that the expression of NGF and the speed of fracture recover have direct correlation in the femur fracture with cerebral injury.