Elias John J, Saranathan Archana
Calhoun Research Laboratory, Akron General Medical Center, 400 Wabash Avenue, Akron, OH 44307, USA.
J Biomech Eng. 2013 Aug;135(8):81011. doi: 10.1115/1.4024287.
The current study was performed to evaluate the accuracy of computational assessment of the influence of the orientation of the patellar tendon on the patellofemoral pressure distribution. Computational models were created to represent eight knees previously tested at 40 deg, 60 deg, and 80 deg of flexion to evaluate the influence of hamstrings loading on the patellofemoral pressure distribution. Hamstrings loading increased the lateral and posterior orientation of the patellar tendon, with the change for each test determined from experimentally measured variations in tibiofemoral alignment. The patellar tendon and the cartilage on the femur and patella were represented with springs. After loading the quadriceps, the total potential energy was minimized to determine the force within the patellar tendon. The forces applied by the quadriceps and patellar tendon produced patellar translation and rotation. The deformation of each cartilage spring was determined from overlap of the cartilage surfaces on the femur and patella and related to force using linear elastic theory. The patella was iteratively adjusted until the extension moment, tilt moment, compression, and lateral force acting on the patella were in equilibrium. For the maximum pressure applied to lateral cartilage and the ratio of the lateral compression to the total compression, paired t-tests were performed at each flexion angle to determine if the output varied significantly (p < 0.05) between the two loading conditions. For both the computational and experimental data, loading the hamstrings significantly increased the lateral force ratio and the maximum lateral pressure at multiple flexion angles. For the computational data, loading the hamstrings increased the average lateral force ratio and maximum lateral pressure by approximately 0.04 and 0.3 MPa, respectively, compared to experimental increases of 0.06 and 0.4 MPa, respectively. The computational modeling technique accurately characterized variations in the patellofemoral pressure distribution caused by altering the orientation of the patellar tendon.
本研究旨在评估计算评估髌腱方向对髌股压力分布影响的准确性。创建了计算模型来代表先前在40度、60度和80度屈曲角度下测试的八个膝关节，以评估腘绳肌负荷对髌股压力分布的影响。腘绳肌负荷增加了髌腱的外侧和后侧方向，每次测试的变化由胫股对线的实验测量变化确定。髌腱以及股骨和髌骨上的软骨用弹簧表示。加载股四头肌后，将总势能最小化以确定髌腱内的力。股四头肌和髌腱施加的力产生了髌骨的平移和旋转。每个软骨弹簧的变形由股骨和髌骨上软骨表面的重叠确定，并使用线性弹性理论与力相关。反复调整髌骨，直到作用在髌骨上的伸展力矩、倾斜力矩、压缩力和侧向力达到平衡。对于施加在外侧软骨上的最大压力以及外侧压缩与总压缩的比率，在每个屈曲角度进行配对t检验，以确定两种加载条件下的输出是否有显著差异（p < 0.05）。对于计算数据和实验数据，加载腘绳肌在多个屈曲角度均显著增加了侧向力比率和最大外侧压力。对于计算数据，加载腘绳肌使平均侧向力比率和最大外侧压力分别增加了约0.04和0.3 MPa，相比之下，实验增加量分别为0.06和0.4 MPa。计算建模技术准确地表征了因改变髌腱方向而导致的髌股压力分布变化。
