Muscle Force Distribution Model of Knee Joint

In this study,a muscle force distribution model of knee joint is established.Muscle length and moment arm were determined from the anatomical model of the lower limb.The results of simulations using generic muscle parameters may not be valid since muscle properties vary from subject to subject.In order to solve this problem,the model calibrated muscle stress using mathematical optimisation to match the net flexion/extension muscle moment with those data from literatures.Sensitivity analyses were also performed to assess the effect of optimum muscle length on estimated muscle contraction force.The result of the study showed a good relationship between optimized muscle moment and knee resultant flexion-extension moment.The joint moments were predicted with multiple correlation coefficient 0.95 for quadriceps and 0.92 for hamstrings.The muscle stresses of the quadriceps and hamstrings obtained through the optimization procedure are 52.4 and 53.8 N/cm2 respectively.Our results of sensitivity analysis also suggest it is especially important to use accurate values of optimal muscle length.The data of optimum muscle length from literature is not valid for subject-specific modeling.