<正> Eight specimens of the knee were used to determine quadricepsforce（FQ）required to stabilize the knee under load in a flexed stance.It wasfound that there was a positive relationship between quadriceps force and theweight and flexion of the knee.At flexion of 15°FQ was about the same as theweight;at 45°

about 3-4 times the weight.FQ increased by 10-40% afterpatellectomy

while anterior displacement of the tibial tubercle by 1.5cm led to11—19%

decrease because of its prolonged lever arm.It widened the angleformed by the quadriceps tendon and the patellar tendon by an average of 10.7degrees.The contact areas of the patellofemoral joint at flexion of 0—135° weredetermined by contact prints.Following anterior displacement of the tibialturbercle

contact areas were upwardly shifted and enlarged.Our results showthat this procedure can decrease the patellofemoral contact stress by lengtheningthe lever arm of FQ

widening the angle formed by the quadriceps tendon andpatellar tendon and enlarging contact areas of the patellofemoral joint.Werecommend it as a possible satisfactory treatment for the patellofemoral jointdisorders.