Biomechanical Properties Of Costal Cartilage In Different Sexes And Layers

bjective:In this experiment,the mechanical properties of the costal cartilage of different genders and layers were tested.The mechanical experiments included tensile stress-strain relationship,compressive stress-strain relationship,stress relaxation and creep test.To explore the differences in mechanical properties of costal cartilage of different genders and layers,to provide theoretical basis for the different layers of mechanical properties of costal cartilage,and to use different layers of costal cartilage in different situations,and to predict the long-term after cartilage transplantation effect.Methods:patients who were more than 12 years old and required costal cartilage were selected and divided into male group?15?and female group?9?according to gender.A1?male central layer?,A2?male edge layer?,B1?female central layer?,B2?female edge layer?.The cartilage remains after engraving of the seventh costal cartilage scaffold,and the cartilage block with different specifications of the central layer and the marginal layer of the costal cartilage is prepared.The rectangular cartilage block has a size of 2.0cm*0.5cm*0.1cm,and is divided into a marginal layer,a central layer,.And a square,the cartilage block size is about 0.5cm*0.5cm*0.2cm,which is divided into edge layer and central layer.On the Q800 DMA Dynamic Thermomechanical Analyzer,the tensile strength test was performed on the rectangular cartilage block,and the square cartilage block was subjected to compressive stress-strain,creep,and stress relaxation experiments.Statistical data were recorded separately for statistical analysis.Results:1.Tensile strengthThe cartilage samples were stretched vertically with 3N/min tension until the stretching force reached 18N.If the cartilage ruptured in advance,the"fracture"was recorded.In the A1?male central layer?group,13 cases had fractures and 2 cases had no fractures.In the A2?male marginal layer?group,15 cases of cartilage blocks were not broken,and the number of fractures between groups was significantly different?p<0.05?,and A1?male central?The fracture rate of the layer group was significantly higher than that of the A2?male edge layer?group;8 cases of fracture occurred in the B1?female central layer?group,1 case was not fractured,and 9 cases of cartilage block in the B2?female marginal layer?group were not broken,and the difference between the groups was significant?p<0.05?,and the B1?female central layer?group fracture rate was significantly higher than the B2?female edge layer?group.2.Stress-strain relationship?compression?The stress-strain curves were obtained by compressing the cartilage specimens for 3N/min until the compressive strength reached 18N.The compressive modulus?E=?/??of cartilage materials under 3N,6N,9N,12N,15N and 18N pressures were recorded respectively.Repeated measurement variance analysis showed that the compression modulus of costal cartilage was different among male groups under different pressure?F?5,140?=121.584,p<0.001?;there was no significant difference in compression modulus between different groups?F?1,28?=1.276,p=0.268?;there was no significant interaction effect between pressure and grouping factors?F?5,140?=2.332,p=0.073?.Compression modulus of costal cartilage was different among female groups under different pressures?F?5,80?=513.066,p<0.001?;there was no significant difference between different groups?F?1,16?=1.778,p=0.201?;there was no significant interaction between pressure and grouping factors?F?5,80?=1.899,p=0.168?.3.Creep?compression?In creep test,we set the load on the material to be 0.1 MPa,the creep time to be 2 minutes,the strain value at 0.5 minutes(l_0.5min)and the strain value at 2 minutes(l_2min)to obtain the strain change value within 0.5minutes to 2 minutes(?l=l_2min-l_0.5min).There was no significant difference in the creep between the two groups,A1?male central layer?and A2?the male edge layer?in the unit time?p>0.05?;the cartilage in the B1?female central layer?and B2?female edge layer?groups.There was no significant difference in the creep variables per unit time?p>0.05?.4.Stress relaxation?compression?In stress relaxation,we set the initial deformation of the material to be 5.0%and the relaxation time to be 2 minutes.The absolute value of stress change(?F=F_2min-F_0.5min)from 0.5min to 2 min was obtained.The absolute difference between them is 0.5 min and 2 min(?F=F_2min-F_0.5min).There was no significant difference in the amount of relaxation of cartilage per unit time between A1?male central layer?and A2?male edge layer??p>0.05?;cartilage of B1?female central layer?and B2?female edge layer?There was no significant difference in the amount of slack per unit time?p>0.05?.Conclusion:?1?In the tensile test,the number of breaks in the central layer was significantly more than that in the marginal layer,indicating that the tensile strength of the costal cartilage in the central layer was worse than that in the marginal layer;?2?In the compression test,the compressive modulus of costal cartilage in the stress-strain test was significantly different under different pressures?F?5,140?=121.584,p<0.001?.In the relaxation test,the stress relaxation in the female marginal layer was significantly different(F?5,140?=121.584,p It was higher than that in the central layer?p<0.05?.There was no significant difference between the other groups.