目的设计制造一种考虑假体尺寸的全膝关节置换术截骨导板(简称截骨导板),实现术中快速、精准定位、辅助截骨的目的。方法截骨导板采用德国EOS公司的FORMIGA P 110三维(3D)打印设备制造,打印材料为聚十二内酰胺(PA12)。通过CT、股骨3D重...目的设计制造一种考虑假体尺寸的全膝关节置换术截骨导板(简称截骨导板),实现术中快速、精准定位、辅助截骨的目的。方法截骨导板采用德国EOS公司的FORMIGA P 110三维(3D)打印设备制造,打印材料为聚十二内酰胺(PA12)。通过CT、股骨3D重建、假体逆向重建获得股骨远端与假体的数字模型,用计算机手术预演确定合理尺寸的假体,固定股骨远端与假体的接触面作为截骨平面,以该平面为基准逐步装配其他部件。3D打印设备模型输入格式为病理性股骨标准模板库(STL),采用选择性激光烧结(SLS)技术生产截骨导板,打印主体材料为聚十二内酰胺(PA12)。制造成品灭菌消毒后,于2019年至2021年用于3例因严重骨关节炎实施的截骨手术,其中男性2例,女性1例;患处位于左侧1例,右侧2例;年龄54~67岁,平均年龄59岁。术中医生严格按照截骨导板使用指南实施截骨手术。统计术中和术后失血量、手术时间、髋膝踝角、胫股角、美国膝关节协会评分(AKS)与美国特种外科医院(HSS)膝关节功能评分对手术结果进行评估。结果成功打印制造截骨导板,主要尺寸:固定钉钉孔到截骨平面的垂直距离10.17~12.51 mm,前髁固定钉钉孔直径3.18 mm;截骨槽宽度1.42 mm,固定钉中心点距离45.44 mm,固定钉钉孔直径3.16 mm。临床试用表明,在截骨手术中使用截骨导板定位股骨远端面,切面呈规则“8”字形状,无明显过切或少切现象,能保证截骨的准确性。未发生摆锯与截骨导板干涉或截骨导板破裂等需要中断手术的事件。术后患者膝关节功能恢复良好,随访过程中未出现假体松动、下沉、膝内外翻畸形、移位、股骨端骨折、脂肪栓塞等不良反应。结论实验研究设计制造的截骨导板能够准确定位,相较于普通截骨工具具有无需开髓、一次安装、多次定位的功能。基于3D打印技术的手术预演有利于医生术前根据患者骨形确定假体规格,提前熟悉截骨参数,预估手术难度,考虑术中可能出现的各种问题,从而制订适合患者的个体化、最优化手术方案。展开更多
The modulus of subgrade reaction ks depends on several factors such as the size and shape of the foundation as well as the embedment depth of the foundation. The present study is an experimental analysis using plate l...The modulus of subgrade reaction ks depends on several factors such as the size and shape of the foundation as well as the embedment depth of the foundation. The present study is an experimental analysis using plate load test to determine the effect of foundation depth, size as well as the shape on the modulus of subgrade reaction (ks) of cohesionless soils. It was carried out by using nine rigid steel plates with different sizes and shapes (circular, square and retangular). The tests were carried out on cohessionless soil with different relative densities under different applied pressures. The settlement has been measured at the surface of the plate for different depths of footings. The ultimate bearing capacity [qu] has been determined from the stress-settlement relationships. The allowable bearing capacity (qa) was determined by dividing the ultimate bearing capacity (qu) by F.S. = 3.0, after which the corresponding settlement (Sa) has been obtained. However, ks was calculated based on dividing the allowable bearing capacity (qa) by the corresponding settlement (Sa). From the present study it is concluded that the subgrade reaction ks of cohessionless soil increases with increasing foundation depth as well as foundation size. In addition, subgrade reaction ks of cohessionless soil under rectangular footing is higher than that under square and that under circular one with same equivalent area. An empirical formula is presented to calculate the subgrade reaction ks of cohessionless soil under square foundation taking into consideration foundation depth. Fair agreement has been obtained between values of ks from the empirical formula at depth of footing = 0.00 B and Biot (1937) as well as Meyerhof and Baike (1965).展开更多
Effects of particle size （A：d50 = 336. 9 μm, B：d50 =123.5μm, C： d50=19.5 μm, D： dso=2.21μm） and content （1 wt% , 3 wt% , 5 wt% , 7 wt% ） of silicon powder on cold crushing strength （CCS） , pore size dis...Effects of particle size （A：d50 = 336. 9 μm, B：d50 =123.5μm, C： d50=19.5 μm, D： dso=2.21μm） and content （1 wt% , 3 wt% , 5 wt% , 7 wt% ） of silicon powder on cold crushing strength （CCS） , pore size distribution and microstructure of Al2O3 - ZrO2 - C refractories coked at high temperature had been investigated by means of mercury porosimeter, SEM, EDS, tic. The results indicated that particle size and content of silicon powder affected the cold crushing strength of coked specimens. It increased with the addition of silicon powder and its finer particle size. However, it decreased greatly when using too fine silicon powder. The particle size and content of silicon powder also impacted the phase evolution and microstructure of coked specimens, much more β-SiC whiskers constituted network structure and well distributed in specimens with reduction of their slenderness ratios when finer silicon powder was added, corresponding to that, the specimens＇ pore size distribution range became narrower with smaller pore diameter, but β-SiC whiskers were distributed sparsely and the specific pore volume of small pores increased when much finer powder was added. It was worthly mentioned that some nitride could form in specimens with addition of appropriate particle size and content of silicon powder.展开更多
基金co-supported by the National Natural Science Foundation of China (No.52005421)the Natural Science Foundation of Fujian Province of China (No.2020J05020)+3 种基金the National Science and Technology Major ProjectChina (No.J2019-I-00130013)the Fundamental Research Funds for the Central Universities,China (No.20720210090)the China Postdoctoral Science Foundations (Nos.2020M682584 and 2021T140634)。
文摘The modulus of subgrade reaction ks depends on several factors such as the size and shape of the foundation as well as the embedment depth of the foundation. The present study is an experimental analysis using plate load test to determine the effect of foundation depth, size as well as the shape on the modulus of subgrade reaction (ks) of cohesionless soils. It was carried out by using nine rigid steel plates with different sizes and shapes (circular, square and retangular). The tests were carried out on cohessionless soil with different relative densities under different applied pressures. The settlement has been measured at the surface of the plate for different depths of footings. The ultimate bearing capacity [qu] has been determined from the stress-settlement relationships. The allowable bearing capacity (qa) was determined by dividing the ultimate bearing capacity (qu) by F.S. = 3.0, after which the corresponding settlement (Sa) has been obtained. However, ks was calculated based on dividing the allowable bearing capacity (qa) by the corresponding settlement (Sa). From the present study it is concluded that the subgrade reaction ks of cohessionless soil increases with increasing foundation depth as well as foundation size. In addition, subgrade reaction ks of cohessionless soil under rectangular footing is higher than that under square and that under circular one with same equivalent area. An empirical formula is presented to calculate the subgrade reaction ks of cohessionless soil under square foundation taking into consideration foundation depth. Fair agreement has been obtained between values of ks from the empirical formula at depth of footing = 0.00 B and Biot (1937) as well as Meyerhof and Baike (1965).
文摘Effects of particle size （A：d50 = 336. 9 μm, B：d50 =123.5μm, C： d50=19.5 μm, D： dso=2.21μm） and content （1 wt% , 3 wt% , 5 wt% , 7 wt% ） of silicon powder on cold crushing strength （CCS） , pore size distribution and microstructure of Al2O3 - ZrO2 - C refractories coked at high temperature had been investigated by means of mercury porosimeter, SEM, EDS, tic. The results indicated that particle size and content of silicon powder affected the cold crushing strength of coked specimens. It increased with the addition of silicon powder and its finer particle size. However, it decreased greatly when using too fine silicon powder. The particle size and content of silicon powder also impacted the phase evolution and microstructure of coked specimens, much more β-SiC whiskers constituted network structure and well distributed in specimens with reduction of their slenderness ratios when finer silicon powder was added, corresponding to that, the specimens＇ pore size distribution range became narrower with smaller pore diameter, but β-SiC whiskers were distributed sparsely and the specific pore volume of small pores increased when much finer powder was added. It was worthly mentioned that some nitride could form in specimens with addition of appropriate particle size and content of silicon powder.
