定制肿瘤人工髋关节假体断裂三维有限元分析及套接式翻修假体的初步应用

Broken custom-made tumor prosthesis with a finite element method and sleeve prosthesis for revision

目的分析断裂的定制肿瘤人工髋关节股骨假体生物力学特性,对其设计进行优化。同时探讨自行设计的套接式翻修假体的应用价值。方法将患者股骨的CT扫描图像用Mimics软件进行处理后连同假体的尺寸导入UG2.0软件造模。后模拟手术将假体、股骨装配,导入到三维有限元软件ABAQUS6.5中进行力学加载分析。针对无松动定制肿瘤人工髋关节的髓外部分发生意外断裂进行翻修而设计了一种套接式翻修假体,并初步应用。结果定制肿瘤人工髋关节假体的股骨颈与髓外柄连接部、髓内柄与髓外柄连接部、髓内柄的内外侧1/3部出现了应力集中,而髓外柄应力均较低。对本例患者进行了19个月的随访,Enneking评分翻修术前为1分,术后为26分。最近一次随访为25分。结论定制肿瘤人工髋关节假体需要在应力集中部位,如假体的尺寸、外形、材料等方面得到加强。套接式翻修假体在其适用范围内有较高的应用价值,近期效果良好,但需进一步随访。

Objective To analyze the biomechanical characteristics of broken tumor prosthesis and optimize them with a finite element method and to evaluate the sleeve prosthesis in revision for custom-made tumor prosthesis fracture. Methods The CT data of femur treated by software Mimics were imported into software UG2.0 to make models, and the prosthesis models were made based on the prosthesis dimension. Then the femur and prosthesis were assembled as the operations were done and imported into a three-dimensional finite dement software ABAQUS6.5 to make a mechanical loading analysis. The sleeve revision prosthesis was designed to repair fracture of the extramedullary site of custom-made tumor prosthesis with no loss. Results In the broken prosthesis, conjunction of the femoral neck and the extrameullary site, conjunction of the extramedullary site and intramedullary site, one third of the intramedullary site on the exterior and interior had stress concentration, but stress of the extramodullary part was weak. Followed up for 19 months, no infection, loss, fracture of prosthesis, recurrence and metastasis, or inequality of the lower limb were observed. The Enneking score of pre-operation was 1, of post-operation was 26, and of the last followed-up was 25. Conclusions We should strengthen many aspects of custom-made tumor prosthesis on the stress concentration site such as the diameter, shape and material. Sleeve revision prosthesis has a high value and a good initial clinical effect in its indication.