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Q:  Something is popping in my knee when I walk. I have no pain on level ground, although I am in pain when I walk up steps and when I kneel. What could this be? Will it heal on its own?

A: It's impossible to identify a precise cause of your symptoms, but your description provides some helpful clues.

A popping noise without pain may be meaningless. A popping noise or sensation with pain could be due to a number of problems, including:

  • Torn cartilage
  • Tendon inflammation
  • Arthritis
  • A loose fragment of bone in the knee (a "loose body")
  • Irritation of the undersurface of the knee cap (as with chondromalacia patella)

Pain when kneeling and walking up steps are common symptoms of chondromalacia patella. In this condition, the cartilage that lines the knee joint softens under the knee cap (patella).

Chondromalacia patella is common in young adults. It is most commonly due to injury, overuse, or an imbalance of muscles around the knee. Sometimes no cause can be identified. Treatment depends on the cause, but usually includes applying ice, taking anti-inflammatory medicines (such as ibuprofen) and pain relievers (such as acetaminophen), exercising the muscles around the knee and avoiding certain high-impact activities. Taping the knee cap or using a knee brace may be recommended.

Other symptoms, such as a feeling that the knee is "giving out," would suggest a ligament injury or tear. Arthritis would usually cause stiffness, aching, or swelling without the popping sound. A loose bone fragment often causes "locking" of the knee, in addition to pain and popping.

I'd recommend an evaluation by your doctor. He or she will be in the best position to recommend treatment, testing, or referral to a specialist.

Robert Shmerling, M.D., is associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center and an associate professor in medicine at Harvard Medical School. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program and has been a practicing rheumatologist for over 25 years.