The Experimental Study On The Treatment Of Infected Bone Defect With 3D Printing Absorbable Drug-releasing Carrier

Objective:Infectious bone defect is usually treated by inserting antibiotic carriers into the bone defect.The commonly used carriers are usually manually prepared,then made into granular by templates,and finally filled into the bone defect.The carrier made by this method has obvious detonation effect and is difficult to maintain long-term stable release effect.In this experiment,two kinds of materials prepared by 3D printing technology were compared with drug carriers prepared by common dies.Methods:The three-layer cylindrical structure and porous cylindrical structure were prepared by 3D printer.1.Preparation:Vancomycin content in each layer of three-layer columnar structure is different.Vancomycin 25 mg,50 mg and 25 mg are respectively contained from top to bottom.The control group is a cylinder manually prepared by mould,each containing 100mg of vancomycin.The total drug content of the two carriers is the same.The porous cylindrical structure weighs 5.0g and contains vancomycin 500mg.The control group is a cylindrical body prepared by the same quality mould.2.Drug release:The three-layer structure replaced the liquid at 1d,3d,5d,7d,10d,14d,18d,22d,26d,30d time points,and the porous structure replaced the liquid at 1d,3d,5d,7d,10d,14d,18D and 22d time points,respectively.The drug concentration in the liquid was detected.The drug release patterns were compared between the two groups.3.Degradation law of carrier:Five samples in each group were put into PBS buffer solution.Five minutes later,the surface water was taken out and dried with filter paper,and the initial mass M₀ was weighed.Then,the samples were put into centrifugal tube and immersed in PBS buffer solution.The three-layer structure was replaced with liquid at 1w,2w,3w,4w,5W and 6w.The porous structure was replaced with liquid at 1st,3d,5d,7d,10d,14d,18D and 22d,respectively.The carrier was taken out and weighed at the time of liquid exchange and comparing quality changes.4.Drug susceptibility test:MRSA bacterial solution was equipped,and the bacterial solution was evenly coated on MH plate with sterile inoculation ring.One vancomycin drug sensitive paper?30?g?and four blank paper pieces were attached to each plate.20?L extract solution was added to each blank paper piece and placed in a constant temperature incubator.After incubation at 37?for 24 hours,the diameter of the bacteriostatic circle was compared between the two groups.Results:1.Drug release regularity:The drug release rate of the three-layer carrier and the control group was high in the initial stage,stable in the middle stage and lasted for more than 30 days.The drug release rate of the experimental group increased on the 18th and22nd days,then decreased gradually.The cumulative release rate of the experimental group was 81.4%,and that of the control group was 82.7%.There was no significant difference in drug concentration between the two groups on the 7th and 10th days,but significant differences were observed at other time points.Porous structure carrier and control group have explosive release phenomenon,but the experimental group is more obvious,the 22-day cumulative release rate is 94.64%in the experimental group and65.36%in the control group.There are significant differences in drug concentration at different time points?2.Degradation characteristics:The percentage of degradation in the three-layer structure experimental group was 92.65%and that in the control group was 81.72%.The effects of grouping,time and the interaction between grouping and time on weight loss rate were statistically significant.The structure of the porous structure experimental group was unstable.On the 7th day,the samples of the experimental group gradually collapsed,while the structure of the control group was complete.On the 22nd day,the weight loss rate of the experimental group reached 96.33%,while that of the control group was33.68%.The interaction of grouping,time and grouping and time had statistical significance on the weight loss rate.3.Antimicrobial susceptibility test results:The diameter of bacteriostasis circle of standard vancomycin susceptible paper was 16.8±0.84 mm?16mm-18mm?.Before 7days,the diameter of bacteriostasis circle of three-layer structure experimental group and control group was larger than that of standard paper.At 10 days and 14 days,the bacteriostasis circle of two groups was smaller than that of standard paper,but there was no significant difference between the two groups at each time point.On the 22nd,26th and30th day,there were still bacteriostasis circles in the experimental group,but nobacteriostasis circles in the control group.In the porous structure experiment and the control group,the diameter of bacteriostasis circle of the two groups was larger than that of the standard paper on the 1st,3rd and 5th day.Starting from the 7th day,the diameter of bacteriostasis circle of the experimental group was smaller than that of the control group,and the difference between the two groups at each time point was statistically significant.Conclusion:In this experiment,two kinds of sustained-release carriers prepared by 3D printing in the experimental group changed the original release and degradation rules by setting their spatial structure and drug distribution.