三维有限元分析内侧半月板全部切除后不同软骨缺损面积对膝关节应力的影响

目的  利用核磁共振成像（MRI）二维图像数据准确构建出膝关节三维有限元模型，采用有限元方法分析内侧半月板全部切除后股骨软骨缺损面积大小对膝关节应力变化的影响。方法  利用膝关节MRI图像建立包括股骨、胫骨、内外侧半月板、内外侧副韧带、前后交叉韧带、髌骨及髌韧带的仿真膝关节数字化模型，在内侧半月板全部切除后的仿真数字化模型上于股骨内侧髁部最容易损伤部位虚拟0.49、0.80、1.0、1.70、2.56及3.24 cm2大小的缺损模型，在股骨上施加1 150 N垂直压应力，类似于在步态周期中的伸直状态，主要分析膝关节软骨及半月板最大压应力与最大剪切应力。结果  内侧半月板全部切除后股骨内侧髁部软骨缺损对内外侧间室接触应力均有影响，但以内侧间室影响较为明显。结论  利用仿真膝关节数字化模型可以有效模拟正常膝关节生物力学变化及内侧半月板全部切除后缺损面积大小对膝关节应力变化的影响。

Finite element analysis of effects of different sizes of osteochondral defect after total medial meniscectomy

Objective To study the reconstruction of three dimensional finite element model based on two-dimensional MRI image data of the knee joint. To explore the stress effects on knee joint from the different sizes of osteochondral defect simulated on the medial femoral condyle after total medial meniscectomy with finite element analysis. Methods A fidelity 3-digital knee model including bones, articular cartilage, menisci and ligaments based on two-dimensional MRI image data was reconstructed. Then we developed a model of a total medial meniscectomy. Six full-thickness cartilage defects (0.49, 0.80, 1.0, 1.70, 2.56 and 3.24 cm2) were simulated on the medial femoral cartilage, which corresponded to the most often damaged condyle. A compressive load of 1,150 N was applied at the top surface of the femur, which corresponded to the load of the gait cycle for a full extension position. The maximalshear stress and maximal compressive stress were investigated. Results The contact stress of both the medial compartment and the lateral compartment of the knee joint was obviously affected by the different sizes of osteochondral defect simulated on the medial femoral condyle after total medial meniscectomy. But the impact of the medial compartment was more obvious than the lateral compartment. Conclusions A 3-digital fidelity knee model can provides a better understanding of the healthy knee contact behavior, and investigates the effect of cartilage defects simulatedon the medial femoral cartilage after total medial meniscectomy on the knee biomechanics.