全髋关节置换术对股骨近端骨重建的影响

目的 采用Wolff骨重建理论分析全髋关节置换（total hip arthroplasty，THA）对股骨近端骨重建进程的影响。方法 根据骨重建控制方程，利用Python语言编写骨重建程序。在ABAQUS软件中分别建立术前股骨模型与术后股骨及假体有限元模型。对比THA手术前后骨重建进程，分析假体植入对THA术后中远期股骨力学性能的影响。结果 假体植入后，股骨近端应力持续降低，受力点由股骨头转移到假体，出现明显的应力遮挡现象。应力遮挡区域内骨丢失现象严重。股骨干皮质骨变薄，应力遮挡有所缓解。假体底端内侧受挤压，应力显著高于外侧，此处骨质分布不均。结论 THA术后股骨近端内侧出现明显的应力遮挡，导致骨丢失，造成假体松动；假体底端两侧应力水平存在差异，引起骨质分布不均，导致假体与股骨配合不紧密，造成术后患者大腿中段的疼痛。

Effects of Total Hip Arthroplasty on Proximal Femoral Bone Remodeling

Objective To analyze the influence of total hip arthroplasty (THA) on the process of proximal femoral bone remodeling by using the Wolff bone remodeling theory. Methods According to control equation of bone remodeling, the program of bone remodeling was written in Python language. Preoperative femur model and postoperative femur and prosthesis finite element models were established respectively in ABAQUS software. The process of bone reconstruction before and after THA operation was compared to analyze the effect of prosthesis implantation on mechanical properties of the femur in the middle and long term after THA operation. Results The stress in proximal femur continued to decrease after prosthesis implantation, and the stress site was transferred from the femoral head to the prosthesis, resulting in an obvious stress shielding phenomenon. Bone loss in the stress shielding area was serious. The femoral shaft cortical bone became thinner and the stress shielding was relieved. The medial side at the bottom of the prosthesis was compressed, and the stress was significantly higher than that of the lateral side, where the bone was unevenly distributed. Conclusions After THA operation, obvious stress shielding occured at proximal medial side of the femur, leading to bone loss and prosthesis loosening. The difference in stress levels on both sides at the bottom of the prosthesis resulted in an uneven bone distribution, causing the discordance between the prosthesis and the femur, as well as postoperative pain in the middle part of the thigh.