全膝关节置换术截骨导板的仿生设计与制造

Bionic design and manufacture of osteotomy guide plate for total knee arthroplasty

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。

Objective To design and manufacture a total knee joint arthroplasty osteotomy guide plate(osteotomy guide plate)considering the size of prosthesis for the arthroplasty,and achieve rapid and accurate positioning and assisted osteotomy during operation.Methods The osteotomy guide plate was manufactured by FORMIGA P 1103D printing equipment from German EOS company,and the printing material was polydodecyl lactam(PA12).The digital model of distal femur and prosthesis was obtained by CT,three-dimensional(3D)reconstruction of femur and reverse reconstruction of prosthesis.The reasonable size of prosthesis was determined by computer operation preview,the contact surface between distal femur and prosthesis was fixed as osteotomy plane,and other components were gradually assembled based on the plane.The model input format of 3D printing equipment was taken as pathological femur standard template library(STL).The osteotomy guide plate was produced by selective laser sintering(SLS)technique,and the main printing material was polydodecalactam(PA12).After sterilization and disinfection of manufactured product,it was used for 3 osteotomy operations for severe osteoarthritis from 2019 to 2021,which included 2 males and 1 female,aged 54-67 years old with mean age of 59 years old;the lesion was located on the left side in 1 case and on the right side in 2 cases.The operation was performed strictly according to guidelines for the use of osteotomy guide.The intraoperative and postoperative bleeding volume,operation time,hip-knee-ankle angle,tibiofemoral angle,American Knee Society(AKS)score and Hospital for Special Surgery(HSS)knee function score were recorded to evaluate operation results.Results The osteotomy guide plate was successfully printed.Main sizes:vertical distance from the fixing screw hole to the osteotomy plane was 10.17-12.51 mm,the diameter of the anterior condylar fixing screw hole was 3.18 mm,width of the osteotomy groove was 1.42 mm,distance between the center point of the fixing screw was 45.44 mm,and diameter of the stanfixing screw hole was 3.16 mm.The results of the clinical trials showed that with the osteotomy guide plate used to locate distal femur in osteotomy operation,the section was in regular“8”shape,with no obvious overcutting or less cutting,which ensured the osteotomy accuracy.There was no interruption of surgery such as interference between swing saw and osteotomy guide plate or rupture of osteotomy guide plate occurred.The knee joint function of patients recovered well after operation,and no adverse reactions such as prosthesis loosening,subsidence,knee varus and valgus deformity,displacement,femoral end fracture and fat embolism occurred during the follow-up.Conclusion It is demonstrated that osteotomy guide plate designed and manufactured by experimental research could accurately locate.Compared to ordinary osteotomy tools,it has the function without opening marrow and one installation multiple positioning.The operation rehearsal based on 3D printing technique is conducive to determining the prosthesis specifications according to bone shape before surgery,familiarizing with osteotomy parameters,estimating difficulty of surgery,and considering various problems that may occur during surgery,so as to formulate an individualized and optimized operative plan suitable for patients.