Wan Qian, Zhang Aobo, Liu Yang, Chen Hao, Zhang Jiangbo, Xue Haowen, Han Qing, Wang Jincheng
Department of Orthopedics, The Second Hospital of Jilin University, Changchun 130000, China.
Heliyon. 2023 Feb 17;9(3):e13819. doi: 10.1016/j.heliyon.2023.e13819. eCollection 2023 Mar.
Obesity is one of the risk factors for osteoarthritis. The end-stage treatment for osteoarthritis is total knee arthroplasty (TKA). However, it remains controversial whether a high body mass index (BMI) affects the initial stability of the femoral prosthesis after TKA. Finite element analysis (FEA) was used to investigate this question in this study.
Four femur models that assembled with TKA femoral components were reconstructed and divided into high BMI group and normal BMI group. The three-dimensional femurs were modeled and assigned inhomogeneous materials based on computed tomography (CT) images. Then each FEA model was applied with gait and deep bend loading conditions to evaluate the maximum principal strain on the distal femur and the relative micromotion between the femur and prosthesis.
The mean strain of the high BMI group increased by 32.7% (936.9 με versus 706.1 με) and 50.9% (2064.5 με versus 1368.2 με) under gait and deep bend loading conditions, respectively, compared to the normal BMI group. Meanwhile, the mean micromotion of the high BMI group increased by 41.6% (2.77 μm versus 1.96 μm) and 58.5% (62.1 μm versus 39.2 μm), respectively. Under gait condition, the maximum micromotion for high BMI group was 33.8 μm and would compromise the initial stability. Under deep bend condition, the maximum strain and micromotion exceeded -7300 με and 28 μm for both groups.
High BMI caused higher strain on the bone and higher micromotion between the prosthesis and the femur. Gait activities could be risky for prosthesis stability in high BMI group while be safe in normal group. Deep bend activities were highly dangerous for both groups with high BMI and normal BMI and should be avoided.
肥胖是骨关节炎的危险因素之一。骨关节炎的终末期治疗是全膝关节置换术（TKA）。然而，高体重指数（BMI）是否会影响TKA后股骨假体的初始稳定性仍存在争议。本研究采用有限元分析（FEA）来探讨这个问题。
重建四个与TKA股骨组件组装在一起的股骨模型，并分为高BMI组和正常BMI组。基于计算机断层扫描（CT）图像对三维股骨进行建模并赋予非均匀材料。然后对每个FEA模型施加步态和深弯加载条件，以评估股骨远端的最大主应变以及股骨与假体之间的相对微动。
与正常BMI组相比，高BMI组在步态和深弯加载条件下的平均应变分别增加了32.7%（936.9με对706.1με）和50.9%（2064.5με对1368.2με）。同时，高BMI组的平均微动分别增加了41.6%（2.77μm对1.96μm）和58.5%（62.1μm对39.2μm）。在步态条件下，高BMI组的最大微动为33.8μm，这会损害初始稳定性。在深弯条件下，两组的最大应变和微动均超过-7300με和28μm。
高BMI导致骨上更高的应变以及假体与股骨之间更高的微动。步态活动对高BMI组的假体稳定性可能有风险，而对正常组则安全。深弯活动对高BMI组和正常BMI组都非常危险，应避免。
