| Research background and purpose:Epidemiological investigation shows that the morbidity and mortality of coronary heart disease are increasing year by year.As an important means of diagnosis and treatment of coronary heart disease,the number of interventional surgery cases is also increasing year by year.At present,the preferred puncture approach for coronary intervention is the radial artery approach.When radial artery puncture fails or is not suitable,the preferred alternative is the femoral artery approach.However,due to the strict bed braking required for patients after femoral artery puncture,the comfort for patients is poor,and the incidence of postoperative massive bleeding is high,some patients refuse to perform coronary artery interventional surgery through femoral artery puncture.Patients undergoing interventional surgery through brachial artery approach do not need strict bed braking,but its clinical application is seldom due to the lack of skilled operators and the poor hemostasis caused by postoperative elbow joint activities of patients,and previous studies have shown that effective braking of elbow joint can shorten the postoperative compression time and reduce the occurrence of postoperative complications.Therefore,the purpose of this study was to develop an external elbow fixation brace with good biosafety and mechanical properties based on 3D printing technology,and to preliminarily evaluate its efficacy in patients undergoing coronary intervention through the brachial artery.Materials and Methods:1.Biological safety evaluation of material:(1)Cytotoxicity test: The 0.2g/ml extraction ratio support and silica gel extract were diluted to 100%,50%,25% and 12.5%as the experimental group,and then 100 ul each of the experimental group and negative,positive and blank control group was added into the 96-well plate containing L929 cells with good growth.Cell morphology and growth were observed under microscope 24 h after culture,and OD values of each group were determined by CCK-8 colorimetry.(2)Skin irritation test: Six New Zealand rabbits were divided into 2 groups(the brace group and the silicone group)with 3 rabbits in each group.24 hours after skin preparation,the brace block,the silicone block,the positive control material and the negative control material were applied to the corresponding parts.24 hours later,the bandage was removed and the residual material was cleaned,and the skin conditions of the corresponding parts were observed 24 hours,48 hours and 72 hours after the bandage removal.2.Complete mechanical property testing of different hollowing modes according to national standards and specifications,including bending test,compression test and impact test,to determine the best hollowing mode.3.Determination of important parameters:(1)Twenty healthy volunteers were selected to wear the elbow external fixation brace with elbow flexion of 0°,30° and 45°for 12 hours.The comfort evaluation table was recovered to determine the most comfortable elbow flexion Angle;(2)Twenty healthy volunteers were selected to wear the elbow external fixation brace without silicone pads or with silicone pads of different thicknesses(3mm,5mm and 8mm)for 12 hours respectively.The comfort,swelling indentation and blisters of each group were compared to determine the best thickness of silicone pads.4.The CT data was converted into CAD data through software processing,and the required elbow external fixation brace was printed by 3D printer using melt deposition molding process.5.Preliminary clinical application: A total of 40 patients undergoing percutaneous brachial artery puncture after coronary intervention were selected and randomly divided into experimental group/brace group and control group/traditional group.The puncture point compression time,pain degree,and related complications of patients within 24 h after surgery were observed and the differences between the two groups were compared.Results:1.(1)Cytotoxicity test: Under the microscope,the cells in the 100% graft group,the50% graft group,the 25% graft group,the 12.5% graft group,the 100% silicone group,the 50% silicone group,the 25% silicone group and the 12.5 silicone group grew well,and no obvious decrease in proliferation was observed compared with the negative control and the blank control group.The cell density of positive control group was significantly decreased compared with that of other groups,and the cells were round and dissolved.CCK-8 test indicated that OD value of positive control group was significantly decreased compared with blank control group,and the difference was statistically significant(P <0.01).OD values of 100%,50%,25%,12.5%,100% silicone gel,50% silicone gel,25%silicone gel,12.5% silicone gel and negative control group had no statistical significance compared with blank control group(P > 0.05).(2)Skin irritation test: 24 h,48h and 72 h after the application of the rabbit was removed,the application sites were observed respectively,and the positive control sites showed obvious redness and swelling,some of which were accompanied by eschar formation;No obvious erythematous edema was observed in the brace group,silicone group and negative control site.Skin irritation evaluation,positive control site skin reaction type was severe;The skin reaction type of brace group,silicone group and negative control site was very mild.2.Mechanical property detection: Bending test: the maximum load and bending strength of rectangular hollow are larger than those of circular hollow and triangular hollow(P < 0.01);Compression test: the maximum load and compression strength of rectangular hollow are larger than those of circular hollow and triangular hollow(P <0.01).Impact test: There was no statistical significance in the work consumed by the round and rectangular hollowed out specimens(P > 0.05),but both of them consumed more work than triangular hollowed out(P < 0.05).3.Twenty healthy volunteers wore the external fixation brace with elbow extension and 0° flexion,30° flexion and 45° flexion for 12 hours respectively on the right upper limb.The results showed that the comfort of the elbow extension was worse than that of30° flexion and 45° flexion(P < 0.01).There was no statistical significance in the comfort of patients with elbow flexion at 30° and 45°(P > 0.05).Twenty healthy volunteers wore the elbow external fixation brace on their right upper extremity for 12 hours with silicone pads padded with 3mm,5mm and 8mm thickness or without silicone pads(0mm).The comfort level and the upper extremity redness,swelling,indentation and blisters were statistically analyzed.The results showed that the comfort level increased with the increase of the thickness of the silicone pads.The comfort of non-padded silicone cushion was worse than that of padded 3mm silicone cushion,and the difference was statistically significant(P < 0.01).The comfort level of 3mm silicone pad was worse than that of 5mm silicone pad,and the difference was still statistically significant(P < 0.05).There was no statistical significance in the comfort level of the elbow external fixation support with5 mm silicone pad and 8mm silicone pad(P > 0.05).In terms of redness,swelling and indentation,there was no statistical significance between the non-padded silicone pad and the padded 3mm silicone pad(P > 0.05),the redness,swelling and indentation of the padded 3mm silicone pad were more obvious than those of the padded 5mm silicone pad(P < 0.01),and there was no statistical significance between the redness,swelling and indentation of the padded 5mm silicone pad and the padded 8mm silicone pad(P > 0.05).No blister appeared in each group.4.The general clinical data of patients in the brace group and the traditional group were compared,and there was no statistical significance in gender,age,smoking,drinking,perioperative use of antiplatelet and anticoagulant drugs between the two groups(P >0.05),indicating comparability.Postoperative puncture point compression time in the support group was shorter than that in the traditional group(P < 0.01).The degree of arm pain in the traditional group was significantly higher than that in the brace group(P <0.01).The upper arm swelling degree in the traditional group was significantly higher than that in the brace group(P < 0.01).There were no significant differences in forearm swelling degree,subcutaneous bleeding area,bleeding type,nerve injury,osteofascial compartment syndrome and color ultrasound examination between the two groups(P >0.05).Conclusions:1.The 3D-printed elbow external fixation support materials and silicone materials used in this study have no cytotoxicity or skin irritation,and have good biological safety.2.Rectangular hollow has the best mechanical properties.3.Wearing elbow flexion of 30°and 45°is more comfortable.Considering the influence of elbow flexion Angle on the position of vascular compressors,the flexion Angle of external fixation support of elbow is determined to be 30 degrees;The elbow external fixation support with 5mm and 8mm silicone pads has the best comfort.In order to reduce the patient’s load and save cost,the thickness of the silicone pads is determined to be 5mm.4.3D printing elbow external fixation supports can reduce the pain of patients after coronary intervention by percutaneous brachial artery puncture,improve the comfort of patients,shorten the puncture point compression time,and reduce the upper arm swelling. |
PDF Full Text Request