This is a pain you feel in the front of your knee. It involves the patella. That's the bone we commonly call the "kneecap." The patella slides up and down in a groove on your femur as you bend and extend your knee. If you have this syndrome, you may have injured the soft tissues that support and cushion your kneecap. Or, you may have some damage to the cartilage on the underside of the kneecap.