The patella rests inside a groove on top of the femur known as the trochlear groove. Whenever you bend and straighten your knee, the patella moves back and forth within this groove. A plastic button, or deal with, is used to resurface the bottom from the patella. This button will line up http://knee cap replacement https://www.theorthopaedicandpainpractice.com/knee-cap-replacement-understanding-the-basics-of-this-orthopaedic-surgery/