There are a few reasons why people experience knee pain. The knee cap lives in the tendon of the quad (front leg muscle). When the quad muscles are tight the knee cap is pulled up and is displaced from the groove between the bones that it lives in. The ITB band that runs down the outside of the upper leg wraps around the knee to keep it secure but when it become tight it pulls the knee cap to the side. The quad, ITB and the hip muscles need to be released using myofascial techniques to allow the knee cap to move back into its correct position.
Flat feet can contribute to discomfort in the knees and hips. It is important to have your arches supported if you have flat feet. The structure of the foot and ankle is very important to the alignment of the whole of the leg and hips.