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目的研究肿瘤型铰链式膝关节置换术后股骨-假体-胫骨复合体正常站立状态下的生物力学响应,探讨病人术后发生股骨穿孔的原因,为肿瘤型铰链式人工膝关节假体的优化设计与制造提供理论基础。方法兼顾CT及三维光学扫描数据建立股骨远端骨肉瘤瘤段切除肿瘤膝关节置换后的病人股骨-假体-胫骨有限元模型,并进行相关有效性验证,从而进一步分析人体站立状态下股骨-假体-胫骨复合体的应力分布及应力遮挡现象。结果 (1)在站立加载状态下,相对胫骨,股骨的应力明显更大且集中分布趋势显著,股骨前1/3区域应力较大,呈现应力遮挡效应。(2)由于模型基于临床病人几何及骨质特征建立,股骨应力集中位置与临床中病人股骨穿孔位置接近,表明在施加自身重力状态下可能发生与病人病症一致的股骨损伤行为。结论肿瘤型铰链式膝关节假体植入后,由于假体髓针深入骨髓腔,正常站立状态下亦对骨髓腔产生一定的压力;由此产生的应力遮挡效应以及假体髓针与特定骨髓腔的匹配情况均可能引起股骨应力集中,从而将可能引起股骨开裂,甚至穿破,影响手术质量。建议术前优化假体设计以减轻或避免此类现象,从而减少术后患者的并发症发生率。
Objective To study the biomechanical response of the femur-prosthesis-tibial composite after standing-up in the patients with tumor-type knee arthroplasty and to explore the reasons for the occurrence of femoral perforation after the operation, and to optimize the tumor-type artificial knee prosthesis Design and manufacture provide the theoretical basis. Methods The femur-prosthesis-tibia finite element model of femur-prosthesis-tibia after resection of the distal femoral osteosarcoma was reconstructed by both CT and three-dimensional optical scanning data. The validity of the femur-tibia model was validated to further analyze the femoral- Stress distribution and stress shielding of prosthesis - tibia complex. Results (1) Under standing load, the stress of the femur was significantly larger and the distribution of the femur was more obvious than that of the tibia. The stress in the first 1/3 area of the femur was larger and showed a stress-shielding effect. (2) Since the model was established based on clinical patient geometry and bone characteristics, the femoral stress concentration was close to the clinical femoral perforation position, indicating that femoral injury may occur consistent with the patient’s condition under self-gravity. Conclusion After implanting the tumor-type knee prosthesis, the prosthetic needles penetrate deep into the medullary canal. Under normal standing conditions, some pressure is exerted on the medullary cavity. The resulting stress shielding effect and the relationship between the prosthetic needles and the specific bone marrow Cavity matching may cause femoral stress concentration, which will likely lead to rupture of the femur, or even wear, affecting the quality of surgery. Preoperative optimization of prosthesis design is recommended to reduce or avoid such phenomena, thereby reducing the incidence of postoperative complications.