3D打印金属垫块修复全膝关节置换(TKA)术中胫骨平台骨缺损的三维有限元分析

Three-dimensional finite element analysis of 3D-printed metal block for repairing tibia plateau bone defect in total knee arthroplasty(TKA)

目的初步探讨3D打印金属垫块在全膝关节置换(total knee arthroplasty,TKA)术中重建胫骨平台缺损的可行性。方法在尸体标本上进行内侧胫骨平台骨缺损造模(AORIⅡ型),作为垫块组,另一侧膝关节不做处理,作为对照组;双侧膝关节经CT扫描后利用Mimics等有限元分析软件,重建骨缺损模型并设计金属垫块,在SolidWorks软件中与胫骨和胫骨平台模块进行装配。通过模拟人体行走时的受力情况,在胫骨平台上施加2000 N的纵向应力,绘制Mises应力云图和Logarithmic应变云图,分析两组模型的胫骨平台上的应力分布;在三维模型的各模块上选择2个观察点,通过分析其受力前后在三维空间中的位移和转角,计算各部分组件的位移和旋转,从而探讨其初始稳定性。结果垫块组的胫骨平台承力区域较对照组小,应力增大,并且应力变化没有对照组平缓。其中,垫块组胫骨平台上、下表面应力集中区域的应力代表值约为0.65和0.75 MPa;对照组则为0.71和0.95 MPa。两组应力较大值的集中区域相同。垫块组中胫骨和胫骨平台在3个方向的位移均略小于对照组;垫块组的胫骨平台和胫骨的内/外翻角度稍大,而前/后倾及内外旋均小于对照组,两组模型中3D金属块本身的位移和旋转角度均非常小,且在安全范围内。结论3D打印金属垫块对于TKA术中胫骨平台骨缺损的修复具有良好的应用前景。

Objective To assess the feasibility of 3D-printed metal block in reconstructing the tibia plateau defect during total knee arthroplasty.Methods The bone defect(AORIⅡtype)was made on the media side of the tibia plateau in a cadaveric specimen as the block model and the contralateral knee joint was regarded as the control model without special treatment.After CT scan,the finite element analysis software such as Mimics was used to reconstruct the bone defect model and design the metal block then assembled with tibia and tibia tray model in SolidWorks software.Two thousands N was applied on the tibia plateau vertically which simulated the condition of the normal walking,Then the stress distribution on the tibia plateau of the two models was analyzed by mapping the Mises stress cloud and the Logarithmic strain cloud.Two points were selected randomly on the tibia,tibia tray and 3D block respectively,the translation and rotation of each point in the three-dimensional space were calculated before and after force application in two modes.Finally,the displacement and rotation angle in three-dimensional space are analyzed for the displacement and rotation of each component to explore its initial stability.Results Compared with the control group,the load-bearing area of the tibia plateau in the block group was smaller and the local stress increased,but the stress change was not as smooth as the control group.The representative stress values on the upper and lower surfaces of the tibia plateau were about 0.65 and 0.75 MPa,while those of the control group were 0.71 and 0.95 MPa.The greatest stress was observed on the same area in the two groups.The displacement of the tibia and tibia tray in three directions were all smaller in the block group.Besides,in the block group,the medial/lateral tilt of the tibia plateau and the tibia was slightly larger,the anterior/posterior tilt and the internal/external rotation were smaller,but the displacement and rotation angle of the 3D-metal block itself were extremely small and within a safe range.Conclusion The 3D printed metal pad has a good application prospect for the repair of the tibia plateau bone defect in TKA.