Chondromalacia Guide: Causes, Symptoms and .
In severe cases, the damaged cartilage can wear away completely, down to the undersurface of the kneecap. If this happens, the exposed kneecap's bony surface can grind painfully against other knee bones. Also, bits of cartilage can float inside the joint, further irritating the cells that line the joint. In response, these cells produce fluid inside the joint (called a joint effusion).