Chondromalacia (KON-dro-mah-LAY-she-ah), also called chondromalacia patellae, refers to softening of the articular cartilage of the knee cap. This disorder occurs most often in young adults and can be caused by injury, overuse, parts out of alignment, or muscle weakness. Instead of gliding smoothly across the lower end of the thigh bone, the knee cap rubs against it, thereby roughening the cartilage underneath the knee cap. The damage may range from a slightly abnormal surface of the cartilage to a surface that has been worn away to the bone. Chondromalacia related to injury occurs when a blow to the knee cap tears off either a small piece of cartilage or a large fragment containing a piece of bone (osteochondral fracture)...The most frequent symptom is a dull pain around or under the knee cap that worsens when walking down stairs or hills. A person may also feel pain when climbing stairs or when the knee bears weight as it straightens. The disorder is common in runners and is also seen in skiers, cyclists, and soccer players. A patient's description of symptoms and a followup x ray usually help the doctor make a diagnosis. Although arthroscopy can confirm the diagnosis, it's not performed unless the condition requires extensive treatment...Many doctors recommend that patients with chondromalacia perform low-impact exercises that strengthen muscles, particularly the inner part of the quadriceps, without injuring joints. Swimming, riding a stationary bicycle, and using a cross-country ski machine are acceptable as long as the knee doesn't bend more than 90 degrees. Electrical stimulation may also be used to strengthen the muscles. If these treatments don't improve the condition, the doctor may perform arthroscopic surgery to smooth the surface of the cartilage and "wash out" the cartilage fragments that cause the joint to catch during bending and straightening. In more severe cases, surgery may be necessary to correct the angle of the knee cap and relieve friction wi