The Study On The Application Of Bone Adhesives In Rat Femoral Fracture Model

Background:With the rapid development of modern economy and industry,the incidence of comminuted fractures caused by high-energy trauma is increasing.It is difficult to use traditional internal fixation devices(plates,screws and intramedullary nails,etc.)to fix comminuted fracture fragments,which is one of the thorny problems in trauma orthopedics.In addition,the removal of internal fixation by secondary surgery brings a certain economic burden and psychological stress to patients.The development of a degradable and resorbable bone adhesive with early mechanical stability and chemical composition similar to bone tissue,is a research hotspot in the field of trauma orthopedic materials.Objective:To investigate the early mechanical stability of the application of bone adhesives in the rat femoral fracture model,as well as the effect of bone adhesives on the local environment of the fracture,so as to provide a theoretical basis for the application of bone adhesive in trauma orthopedics.Methods:We designed four types of bone adhesives.Bone adhesive 1 was composed of methacrylic anhydride gelatin(Gel MA)and mineralized nano-hydroxyapatite(n HA).Bone adhesive 2 was composed of methacrylic anhydride gelatin(Gel MA),mineralized nano-hydroxyapatite(n HA)and polyethylene glycol diacrylate(PEGDA).Bone adhesive 3 is composed of methacrylic anhydride gelatin(Gel MA),mineralized nanohydroxyapatite(n HA)and chondroitin sulfate modified dopamine(CSDA).Bone adhesive 4 is composed of methacrylic anhydride gelatin(Gel MA),mineralized nano-hydroxyapatite(n HA)and oxidative chondroitin sulfate modified methacrylic anhydride(O-CS-MA).All rats were divided into internal fixation group,control group,bone adhesive 1group,bone adhesive 2 group,bone adhesive 3 group,bone adhesive 4group,and untreated group after fracture,which were applied to the model of the rat femoral fracture.Then the footprint map was analyzed 3 days after the operation and X-rays were taken at 2w,4w after the operation.The three-point bending test of the rat femur was taken to analyze the early mechanical stability of the bone adhesives.Combined with imaging data and HE staining of local tissue at the fracture end,the effect of bone adhesive on the local environment of fracture was analyzed.RESULTS:The load test showed that the maximum load value of bone adhesive4(Gel MA+n HA+O-CS-MA)group was 4.65±0.88 N,and compared with the internal fixation group(5.22±0.45N),there was no statistical difference(P > 0.05);in the pressure test,the maximum pressure of bone adhesive 4(Gel MA+n HA+O-CS-MA)group is 2.2±0.13 mpa,and the maximum pressure of bone adhesive 2(Gel MA+n HA+PEGDA)group is2.01±0.81 Mpa,compared with 2.46±0.34 mpa in the internal fixation group,there was no statistical difference(P>0.05).HE staining of local tissue showed among the goup of bone adhesive 1,bone adhesive 2,bone adhesive 3 and bone adhesive 4,osteoblasts increased around the area of fracture and the bone adhesive.The footprint map of rats showed that in the early stage of fracture healing,the proportion of normal weight-bearing walking footprints in all bone adhesive groups(79%)was higher than that in the internal fixation group(50%)and the group without internal fixation after fracture(33%).Conclusion:1.All four new bone adhesives may have bone promoting properties.2.The four kinds of bone adhesives have certain mechanical stability,and the mechanical strength of bone adhesive 4 is the best.