PDF(Pubmed)
Abstract：
OBJECTIVE: To investigate the differences of patellofemoral joint pressure and contact area between the process of stair ascent and stair descent.
METHODS: The finite element models of 9 volunteers without disorders of knee (9 males) to estimate patellar cartilage pressure during the stair ascent and the stair descent. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and ligament model. The three-dimension models of the patella, femur and tibia were developed with the medical image processing software, Mimics 11.1. The ligament was established by truss element of the non-linear FE solver. The equivalent gravity direction (-z direction) load was applied to the whole end of femur (femoral head) according to the body weight of the volunteers, and the force of patella was observed. A paired-samples t-test or Wilcoxon rank sum test to make comparisons between stair ascent and stair descent. Statistical analyses were performed using SPSS 22.0 using a P value of 0.05 to indicate significance.
RESULTS: During the stair descent (knee flexion at 30°), the contact pressure of the patella was 2.59 ± 0.06Mpa. The contact pressure of femoral trochlea cartilage was 2.57 ± 0.06Mpa. During the stair ascent (knee flexion at 60°), the contact pressure with patellar cartilage was 2.82 ± 0.08Mpa. The contact pressure of the femoral trochlea cartilage was 3.03 ± 0.11Mpa. The contact area between patellar cartilage and femoral trochlea cartilage was 249.27 ± 1.35mm2 during the stair descent, which was less than 434.32 ± 1.70mm2 during the stair ascent. The area of high pressure was located in the lateral area of patella during stair descent and the area of high pressure was scattered during stair ascent.
CONCLUSIONS: There are small change in the cartilage contact pressure between stair ascent and stair descent, indicating that the joint adjusts the contact pressure by increasing the contact area.
METHODS: The finite element models of 9 volunteers without disorders of knee (9 males) to estimate patellar cartilage pressure during the stair ascent and the stair descent. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and ligament model. The three-dimension models of the patella, femur and tibia were developed with the medical image processing software, Mimics 11.1. The ligament was established by truss element of the non-linear FE solver. The equivalent gravity direction (-z direction) load was applied to the whole end of femur (femoral head) according to the body weight of the volunteers, and the force of patella was observed. A paired-samples t-test or Wilcoxon rank sum test to make comparisons between stair ascent and stair descent. Statistical analyses were performed using SPSS 22.0 using a P value of 0.05 to indicate significance.
RESULTS: During the stair descent (knee flexion at 30°), the contact pressure of the patella was 2.59 ± 0.06Mpa. The contact pressure of femoral trochlea cartilage was 2.57 ± 0.06Mpa. During the stair ascent (knee flexion at 60°), the contact pressure with patellar cartilage was 2.82 ± 0.08Mpa. The contact pressure of the femoral trochlea cartilage was 3.03 ± 0.11Mpa. The contact area between patellar cartilage and femoral trochlea cartilage was 249.27 ± 1.35mm2 during the stair descent, which was less than 434.32 ± 1.70mm2 during the stair ascent. The area of high pressure was located in the lateral area of patella during stair descent and the area of high pressure was scattered during stair ascent.
CONCLUSIONS: There are small change in the cartilage contact pressure between stair ascent and stair descent, indicating that the joint adjusts the contact pressure by increasing the contact area.
摘要：
目的：研究楼梯上升和楼梯下降过程中髌股关节压力和接触面积的差异。
方法：9名没有膝关节疾病的志愿者（9名男性）的有限元模型，以估计楼梯上升和楼梯下降期间的髌骨软骨压力。模拟考虑了磁共振成像的软骨形态，来自负重磁共振成像的关节姿势，和韧带模型。髌骨的三维模型，股骨和胫骨是用医学图像处理软件开发的，Mimics11.1.韧带是通过非线性有限元求解器的桁架单元建立的。根据志愿者的体重，对整个股骨末端（股骨头）施加等效重力方向（-z方向）载荷，并观察髌骨受力情况。采用配对样本t检验或Wilcoxon秩和检验对楼梯上升和楼梯下降进行比较。使用SPSS22.0进行统计学分析,P值为0.05以指示显著性。
结果：在楼梯下降期间（膝盖弯曲30°），髌骨接触压力为2.59±0.06Mpa。股骨滑车软骨接触压力为2.57±0.06Mpa。在楼梯上升过程中(膝盖弯曲60°),与髌骨软骨的接触压力为2.82±0.08Mpa。股骨滑车软骨的接触压力为3.03±0.11Mpa。在楼梯下降过程中，髌骨软骨与股骨滑车软骨的接触面积为249.27±1.35mm2，在楼梯上升过程中小于434.32±1.70mm2。在楼梯下降过程中，高压区域位于髌骨的外侧区域，而在楼梯上升过程中，高压区域分散。
结论：在楼梯上升和楼梯下降之间的软骨接触压力变化很小，表明接头通过增加接触面积来调节接触压力。
方法：9名没有膝关节疾病的志愿者（9名男性）的有限元模型，以估计楼梯上升和楼梯下降期间的髌骨软骨压力。模拟考虑了磁共振成像的软骨形态，来自负重磁共振成像的关节姿势，和韧带模型。髌骨的三维模型，股骨和胫骨是用医学图像处理软件开发的，Mimics11.1.韧带是通过非线性有限元求解器的桁架单元建立的。根据志愿者的体重，对整个股骨末端（股骨头）施加等效重力方向（-z方向）载荷，并观察髌骨受力情况。采用配对样本t检验或Wilcoxon秩和检验对楼梯上升和楼梯下降进行比较。使用SPSS22.0进行统计学分析,P值为0.05以指示显著性。
结果：在楼梯下降期间（膝盖弯曲30°），髌骨接触压力为2.59±0.06Mpa。股骨滑车软骨接触压力为2.57±0.06Mpa。在楼梯上升过程中(膝盖弯曲60°),与髌骨软骨的接触压力为2.82±0.08Mpa。股骨滑车软骨的接触压力为3.03±0.11Mpa。在楼梯下降过程中，髌骨软骨与股骨滑车软骨的接触面积为249.27±1.35mm2，在楼梯上升过程中小于434.32±1.70mm2。在楼梯下降过程中，高压区域位于髌骨的外侧区域，而在楼梯上升过程中，高压区域分散。
结论：在楼梯上升和楼梯下降之间的软骨接触压力变化很小，表明接头通过增加接触面积来调节接触压力。
