Knee care: why is my knee making noises?

My left knee has started to give me trouble, especially when I am squatting in the gym and going up and down stairs. If I bend the knee, there is a gently crunching and grinding sound behind the kneecap. I am 22 years old and healthy, although slightly overweight.

Dr Fred Kavalier answers your health question:

This is likely to be chondromalacia patellae. The patella is the kneecap, and the back surface of it is lined with cartilage. The cartilage acts as a buffer, which allows the kneecap to slide over the front of the knee joint whenever the knee is bent. The cartilage behind the kneecap is supposed to be firm and smooth. If, for unknown reasons, it becomes softer than normal, the smooth surface becomes rough and irregular. The grinding noise is caused by the rough cartilage rubbing against the knee bones. The best treatment is a combination of rest, painkillers and physiotherapy, to maintain the strength of the muscles around the knee joint. The Arthritis Research Campaign publishes a comprehensive booklet about chondromalacia patellae (www.arc.org.uk; 0870 850 5000).

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.