| Abstract:Objective:To explore external fixation pins that is effective, practical, less side effects, prevention of infection with itself, and demonstrate the feasibility, superiority and the possible antibacterial mechanism of this method through the animals experiment that compared infection rate, which can provide an objective basis and theoretical support for late-stage clinical application. Method:1. Materials:Stainless steel external fixation pins,HA powder,FumatT200-4 anti-bacterial powder,Suspension of Staphylococcus aureus (ATCC 25923 Standard Strain), New Zealand white rabbits as experimental animals, healthy 3-6 months old.2. Antimicrobial testing and prevention of infection in animal samples were sub-groups:the experimental group containing silver screw fixation of hydroxyapatite coated and control groups of stainless steel screw fixation group.3. Preparation of experimental model:Take 95wt% of hydroxyapatite powder and 5wt% FumatT200-4 anti-bacterial powder mixed, and stainless steel fixation screws for plasma sprayed. Control groups were to be disinfected with external fixation pin spare, rabbits made a total of 24 pollution model, the average weight of 2.32±0.06Kg, female 11, male 13, a list of random row were randomly divided into 2 groups,12 in each group, rabbits were anesthetized for ketamine 50mg/kg line muscle. Fixation pins were placed in femur, Staphylococcus aureus suspension was injected into the pin tract. Compared effect of infection prevention between two kinds of fixation pin hole on the rabbit model of S. aureus.4. Specimen collection and data collection techniques:measured of rabbit body temperature, body weight daily. Phlebotomize blood samples for blood, C-reactive protein test on1,3,7,14,28 days after operation. Take soft tissue surrounding pin tract for pathological examination and bacteria culture on 1,3,7,14,28 days after surgery. Results 1.24 external fixation pins placed in femur and raised rabbit model of Staphylococcus aureus contamination. Rabbit died during the experiment, make up 24,26 completed the final test, female 15, and male 11.2. Two rabbits infected in experimental group, the control group infected 11.Infection rates between experimental group and control group are significantly different (P<0.05).3. Compared body weight of rabbits between experimental group and control group in 1,3,7,14 and 28 days after surgery (P> 0.05), the difference was not statistically significant.4. Compared rectal temperature of rabbits between experimental group and control group at 1,3,7,14 and 28 days after surgery compared (P> 0.05), the difference was not statistically significant. 5. Experimental rabbits the blood leukocyte count and CRP levels were significantly lower than the control group in 3,7,14 days (P<0.05), the difference was statistically significant. However, (P>0.05) difference was not statistically significant between the two groups control on 1 and 28 days after surgery. The rabbits that were infected had abscess in the incision, skin irritation surrounding, some associated with sinus formation and pus spills. External fixation pin cohered around the yellow-white pus and some necrotic tissue. Secretions of infected rabbits were taken pus bacterial culture, S. aureus was cultured. Histopathologic examination of soft tissue that around external fixation pin (HE stain) shows:there are necrotic tissues, a large number of neutrophils, lymphocytes, monocots, plasma cells. Fibrosis and inflammatory necrosis lesions coexist the late. Conclusion external fixation pins of Ag-HA coating can be effective in preventing pin tract infection in rabbit model which infected by Staphylococcus aureus. And provide adequate practical basis for clinical applications. |
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