基于步态分析建立膝关节三维有限元模型（英文）

A Dynamic Finite Element Model of Knee Joint Based on Gait Analysis

目的：在静态三维有限元模型基础上结合下肢的三维步态数据,建立动态有限元模型,模拟人体在平地行走过程中下肢随着角度和地面反作用力的变化而出现膝关节内的应力改变。为后续研究提供生物力学客观结局指标。方法：拍摄男女各1名志愿者的膝关节MRI影像,使用Mimics、Geomagic、Ansys等软件建立2例双膝4个有限元模型。获取2名志愿者的三维步态数据,并导入静态有限元模型中建立膝关节动态有限元模型,进行验证后计算内外侧半月板体积及应力在行走中的变化。结果：股骨和胫骨为刚体结构,网格大小为2 mm,单元数分别为6 349和4 020,节点数分别为18 945和11 966。半月板弹性模量为120 MPa,泊松比为0.45,网格划分大小为1 mm,内外侧半月板单元数和节点数分别为25 801和23 241及36 903和33 488。男性内外侧半月板体积均大于女性,但男女性双膝内外侧半月板体积比值接近,男性左右膝内、外侧半月板比值为0.99和0.97,女性为0.93和0.96。内侧半月板应力较外侧大,比值在1.11-1.43之间。女性半月板应力分布较男性更为不对称（1.22-1.27 vs 1.11-1.14）。结论：结合步态数据建立的膝关节动态有限元模型能对膝关节的生物力学环境进行仿真模拟,反映出步行过程中不同事件下半月板应力的变化情况。

Objective： Combined with a static finite element model of knee joint and the gait data, a dynamic finite element（FE） model was established to simulate the stress change within the knee joint during level walking,aiming to provide an objective outcome measurement from biomechanical perspectives. Methods： Knee MRI images of a male and a female volunteers were scanned, four FE models were built by using Mimics, Geomagic, Ansys software. Gait data was imported to static finite element model to establish the dynamic FE model of knee joint during level walking. Models were verified before the volumes and stress on medial and lateral menisci were calculated in it. Results： The rigid structure of femur and tibia was set with grid size of 2 mm. The elements were6,349 and 4,020, and the nodes were 18,945 and 11,966 respectively. Elastic material of menisci was set with grid size of 1 mm, elastic modulus of 120 MPa and poisson＇s ratio of 0.45. The elements of medial and lateral meniscus were 25,801 and 23,241, and nodes were 36,903 and 33,488. The volumes of medial and lateral menisci in the male volunteer were bigger than those in female one. But volume ratio between medial and lateral menisci on both knees was close in two volunteers. Ratios of medial and lateral menisci on left and right knee in male volunteer were 0.99 and 0.97, while in female volunteer were 0.93 and 0.96. Larger stress was shown on medial meniscus than on lateral part which ratio was between 1.11-1.43. Stress on medial meniscus was more concentrate and stress distribution on two menisci was less symmetrical in female than in male（1.22-1.27 vs 1.11-1.14）. Conclusion：Knee dynamic finite element model by integrated gait data could well reflect stress change in menisci at different events during level walking.