Chondromalacia patellae typically develops in adolescents. Joggers are especially susceptible. The cause of chondromalacia patellae is probably a minor, repetitive injury resulting from misalignment of the kneecap. The misalignment causes the cartilage on the underside of the kneecap to grate against other bones when the knee bends.
(See also Overview of Hereditary Connective Tissue Disorders Overview of Connective Tissue Disorders in Children Connective tissue is the tough, often fibrous tissue that binds the body's structures together and provides support and elasticity. Muscles, bones, cartilage, ligaments, and tendons are built... read more .)
Dull, aching pain is felt all around and behind the knee. There is no swelling. Climbing (especially going up or down stairs), playing certain sports, sitting for a long time, and running usually worsen the pain.
A doctor bases the diagnosis of chondromalacia patellae on the symptoms and a physical examination.
The doctor may recommend exercises to strengthen the quadriceps muscles, which straighten or extend the knee joint. Increasing knee flexibility with stretching exercises helps. Activities that worsen the pain (typically those that involve bending the knee) should be avoided for several days. Ice and nonsteroidal anti-inflammatory drugs Nonsteroidal Anti-Inflammatory Drugs In some cases, treating the underlying disorder eliminates or minimizes the pain. For example, setting a broken bone in a cast or giving antibiotics for an infected joint helps reduce pain.... read more (NSAIDs), such as ibuprofen or naproxen, can help relieve symptoms.
Occasionally, the undersurface of the kneecap must be smoothed with a small (about the diameter of a pencil) fiberoptic scope called an arthroscope Arthroscopy A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more , which allows the doctor to look inside the joint.