The patella rests in the groove in addition to the femur known as the trochlear groove. After you bend and straighten your knee, the patella moves back and forth inside this groove. People with osteoarthritis only in one fifty percent with the knee joint (the interior facet) should be given the choice http://knee cap replacement https://www.theorthopaedicandpainpractice.com/knee-cap-replacement-understanding-the-basics-of-this-orthopaedic-surgery/