Chondromalacia

What Is It?

The joints in your body are cushioned with a type of connective tissue called articular cartilage. This tough, rubbery tissue covers the ends of bones inside a joint. As the joint moves, the cartilage helps to cushion the bones. It also allows the ends of the bones to glide smoothly against one another.

In chondromalacia, the cartilage inside a joint softens and breaks down. When this happens, the cartilage loses its ability to cushion and protect the ends of the bones as the joint moves. As a result, the ends of the bones can rub together, causing joint pain.

Although chondromalacia can affect any joint, the most common location is inside the knee, where it usually begins as a small area of painful, softened cartilage behind the kneecap (patella). Eventually, this area can become larger, and the softened cartilage can crack or shred into a mass of fibers. 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 space, further irritating the lining of the joint and producing fluid inside the joint (called a joint effusion).

Many different types of joint injuries and joint disorders can lead to chondromalacia. In the knee joint, the most common causes involve injury, overuse of the knee, and poor alignment of the muscles and bones around the knee joint. These causes include:

• Trauma, especially a fracture (break) or dislocation of the kneecap
• A mechanical imbalance of the muscles around the knee
• Overuse (repeated bending or twisting) of the knee joint, especially during sports
• Abnormal alignment of the muscles or bones near the knee joint
• Injury to a meniscus (C-shaped cartilage inside the knee joint)
• Rheumatoid arthritis or osteoarthritis
• An infection in the knee joint
• Repeated episodes of bleeding inside the knee joint
• Repeated injections of steroid drugs into the knee

Chondromalacia of the knee affects young adults more than any other age group. It is especially common in runners, joggers, skiers, soccer players, cyclists and other athletes who repeatedly stress their knees. Also, workers who spend a lot of time kneeling — particularly carpet layers, tile setters and floor layers — have an increased risk of developing this joint problem.

Symptoms

The most common symptom of chondromalacia is a dull, aching pain in the front of your knee, behind your kneecap. This pain can worsen when you go up or down stairs. It also can flare up after you have been sitting in one position for a long time. For example, your knee may be painful and stiff when you stand up after watching a movie or after a long trip in a car or plane.