Design And Experimental Study Of Internal Fixation Plates With Anti-infective Function

Objective 1. To design a internal fixation plates with anti-infective function, which can avoid the infection after internal fixation operation. 2. Use HPLC to find out these plates' drug-releasing rule and whether ethylene oxide would lower the concentration of anti-bacterial agents on the plates. 3. To knowledge these plates' drug-releasing rule in the animal experiment.Methods 1,Picking 0.5～1.0g wound's tissue of 100 open fracture patient up to germicult, based the result to decide the antibiotic what the experiment use. 2,To smear 0.4g cefazolin onto a cylindrical stainless steel which is 5cm long and 4mm diameter, then we smear some degradable organic matter on the cefazolin. 3,In this experiment, the 8 cylindrical stainless steel is devided into 2 groups: one group is sterilized by ethylene oxide and the other group is not sterilized. We put the two group into the phosphatic solution which temperature remains 37℃and make its PH=7.40. At last, we use HPLC to find these plates' drug-releasing rule, effective-anti-infective time and whether ethylene oxide would lower the concentration of anti-bacterial agents on the plates. 4,Put 20 cylindrical stainless steel into the rabbits' left greater trochanter. And then, we use HPLC to detect concentration of cefazolin in the blood and in the soft tissue around cylindrical steel.Results 1,We can find the grampositive and gramnegative bacterias all in the wound, grampositive bacterias mainly is staphylococcus aureus, gramnegative bacterias mainly is escherichia coli. And the bacterias is sensitive to Vancomycin,cefazolin and Ceftazidime, so we select cefazolin in our experiment. 2,The cefazolin concentration in the phosphatic solution was considerable high (the highest concentration is 58.53μg/ml), in the next 2 days, the concentration was gently decline. In the 17th day, the cefazolin concentration in the phosphatic solution is remain 7.1μg/ml(the MIC of cefazolin is 0.1～6.3μg/ml), and we find phosphatic solution is remain 7.1μg/ml(the MIC of cefazolin is 0.1～6.3μg/ml), and we find out the ethylene oxide can not lower the concentration of anti-bacterial agents on the plates. 3,After insert the cylindrical steel into the rabbit's body, the highest concentration of cefazolin is 30.47μg/ml, in the 2nd day, the concentration has climbed a peak value. After the 3rd day, the concentration of cefazolin is gently decline. And the effective concentration is last 14 days.Conclusions: The internal fixation plates we designed has a effective anti-infective function whether in or out of the animal's body, which can allow the sterilization by ethylene oxide. This internal fixation plates which have anti-infective function have a brilliant future to avoid infection after operations of internal fixations.