Chondromalacia patellae (patellofemoral syndrome) is softening of the cartilage under the kneecap (patella).

Chondromalacia patellae typically develops in adolescents. Joggers are especially susceptible. The cause 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.

Dull, aching pain is felt all around and behind the knee. 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 on the symptoms and physical examination and 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 should be avoided. Ice and analgesics or nonsteroidal anti-inflammatory drugs (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 (arthroscope), which allows the doctor to look inside the joint.

Last full review/revision February 2008 by Frank Pessler, MD, PhD; David D. Sherry, MD