The knee joint is surrounded by fluid-filled sacs termed bursae, which function gliding surfaces that reduce friction of your tendons. Underneath the kneecap, You will find a massive tendon (patellar tendon) which attaches for the front with the tibia bone. Please wait around a few minutes and check out again. https://www.theorthopaedicandpainpractice.com/what-should-i-do-if-i-have-a-collateral-ligament-injury-of-the-knee/?_gl=1*xbbxlb*_up*MQ..&gclid=Cj0KCQjwkt6aBhDKARIsAAyeLJ2krYJSOuy5mZksrNqH-VDjQwW1ScD49yD8BUWysDG6u6bJPCSbXVUaAuCPEALw_wcB