Experimental Study Of Platelet-rich Fibrin In Flap Transferred On Bone Exposed Wound

Objective:To investigate the effect of local application of platelet-rich fibrin(PRF)on the survival of random flaps covered with bone exposure,to understand the role of self-derived PRF in the process of flap transfer,and to further explore the mechanism of PRF effecting the growth of flaps.To provide a theoretical basis for the clinical application of PRF and the treatment of refractory wounds.Content:Thirty New Zealand rabbits of clean grade,weighing 2.4 kg to 3.0 kg,were provided by the Animal Experimental Center of Southeast Hospital affiliated to Xiamen University,with normal diet.Thirty New Zealand rabbits were randomly divided into two groups,experimental group and control group,15 rabbits in each group.The whole blood of New Zealand rabbits was collected,20 mL,3000r/min and centrifuged 10min was used to prepare PRF.The experiment was divided into 3-day 7-day and 14-day groups with 5 New Zealand rabbits in each group.4cm×2cm flap on the head of New Zealand rabbit.The pedicle is located at the osseous eminence of the proximal side of the skull,the width of the flap is the same as that of the two ears.Parallel to the line,each group was given the following treatment:the periosteum of the corresponding position under the flap was removed after the formation of the flap,?experimental group,the PRF was evenly covered on the skull after the periosteum was removed.The"5-0"silk thread was sutured in situ along the flap for three weeks.Alter the suture was finished,the sterile gauze was folded and placed on the upper part of the flap.Use appropriate pressure to pack up;?control group:after removing periosteum,no treatment can be done,the rest is the same as before.The survival rate and survival rate of the flap were observed 3-day?7-day and 14-day after operation.The tissue mass of the flap was also removed for histological observation.Density was calculated,VEGF was detected by immunohistochemistry,CD34 were detected by immunohistochemistry.The difference of the density of new vessels and the survival of flap was analyzed between the experimental group and the control group,whether there was significant difference between the experimental group and the control group in the density of new vessels and the survival rate of the flap,and whether there were significant differences between the experimental group and the control group.The mechanism of its action was also discussed.Results:1.Gross observation shows that the surviving flaps are soft,ruddy,bleeding when cutting or needling,and the necrotic flaps are hard and dark,and there is no bleeding when cutting or needling.The necrotic area of the skin flap in each time group was smaller than that in the control group,the color was close to the normal tissue,the tissue edema was generally lighter,and the flap was located at the distal end of the flap.2.The survival rate of the flap in the experimental group was not different from that in the control group,but with the extension of time,the survival rate of the flap in the experimental group was higher than that in the control group.3.Histopathological observation and vascular density measurement showed that the inflammatory reaction of the flaps in each time group was lighter and lighter with the extension of time,and the inflammatory reaction was the lightest and the blood vessel density was the largest in the 14-day group.The inflammatory reaction in the experimental group was lighter than that in the control group,and the vascular density in the experimental group was greater than that in the control group.4.The positive rate of VEGF and CD34 in the experimental group was higher than that in the control group.Conclusion:Platelet-rich fibrin can increase the tissue microvessel density of random flap significantly,can also improve the survival rate of random flap.