Your hamstring muscle, whose function is to bend the knee and straighten the hip, is found in the back of your thigh. Tension and trigger points in the hamstring muscles often lead to pain in the hollow of the knee when walking or sitting. This muscle group is best massaged with the pressure-motion technique.
Often weak butt muscles are to blame for pain behind the knee, but. As you bend and straighten your leg you'll feel a swollen lump and pain behind your knee .
"Muscle knots are actually hyperirritable spots in muscle or fascial tissue [bands. IT band area, which runs along the outside of the leg from the hip to the knee .