Do you have pain in the front of your knee and feel a grinding sensation when you bend your knee? If so, you may have chondromalacia patella. This is the breakdown of articular cartilage on the underside of the kneecap (patella). Articular cartilage is a tough, elastic tissue that covers the ends of bones in the most mobile joints in the body, including the knees. It allows for smooth, pain-free movement.