The knee joint is surrounded by fluid-loaded sacs identified as bursae, which serve as gliding surfaces that decrease friction of your tendons. Underneath the kneecap, There's a large tendon (patellar tendon) which attaches into the front of the tibia bone. Fractures in almost any of these bones can take place 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