Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Barbara K. Hecht, PhD
Chondromalacia, technically termed chondromalacia patellae, is the most common cause of chronic knee pain. The condition develops due to softening of the cartilage beneath the knee cap (the patella), resulting in small areas of breakdown and pain around the knee. Instead of gliding smoothly over the knee, the knee cap rubs against the thigh bone (the femur) when the knee moves. The changes can range from mild to complete erosion of the cartilage. This process is sometimes referred to as the patellofemoral syndrome.
Chondromalacia commonly occurs in females. Girls in their teens are at elevated risk because the cartilage of the knee is subjected to excessive and uneven pressure due to the structural changes that accompany rapid growth. Chondromalacia may also occur in adults over age 40 as part of the wear-and-tear process that eventually leads to osteoarthritis of the knee joint. Other factors that may precipitate chondromalacia include trauma, overuse, or abnormal forces on the knee joint. It can develop in skiers, runners, cyclists, and soccer players, especially if someone is knock-kneed or flat-footed.
The pain of chondromalacia occurs in the front or inside of the knee. The pain is generally worse with activities such as running, jumping, using stairs, or kneeling. The pain is also typically worse after prolonged sitting with the knees bent. This pain is called the "theater sign" of chondromalacia.
There may be tenderness of the knee along with a grating or grinding sensation when the knee is extended. X-rays of the knee are generally normal in chondromalacia but may show a slight displacement of the knee cap. (Even if you have symptoms consistent with chondromalacia, your doctor may still order an X-ray to rule out other reasons for your knee pain.)
Chondromalacia is usually treated conservatively with exercises designed to strengthen the muscles around the knee and restore normal alignment of the knee cap. These exercises should be carefully designed to selectively strengthen the thigh muscles (the quads) and realign the patella.
About 85% of patients with chondromalacia improve with conservative treatment alone and require no further therapy. In about 15% of cases, the pain persists or worsens to the extent that surgical correction of the knee joint may be needed. While it is not always possible to prevent chondromalacia, avoiding trauma and abnormal stresses on the knee and keeping the leg muscles strong and flexible may be able to help to prevent its development in many cases.
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