Q: My 16 year old son is a long-distance runner. He started having a lot of knee pain and his doctor said it was Runners Knee and prescribed rest. What is it and is there anything else he can do for it?

A: Runner's knee, or chondromalacia patellae, can be caused by several things. In young people, it's most often caused by overuse, such as running. It can also be caused by injury, misalignment of the kneecap or arthritis.

The standard treatment for this problem is rest and limited activity. Nonsteroidal anti-inflammatories (NSAIDs) may help, as well. Your son's doctor may have prescribed physiotherapy, which would likely be helpful because a physiotherapist can check to see how your son walks and runs. A step that is off just a bit could throw the balance, affecting the knee. Finally, it has also been found that worn out running shoes, or incorrect running shoes, can contribute to this type of knee problem.

Reference: Harri K. Pihlajamaki, MD, et al. Reliability of Clinical Findings and Magnetic Resonance Imaging for the Diagnosis of Chondromalacia Patellae. In The Journal of Bone & Joint Surgery. Feb. 2010. Vol. 92. No. 4. Pp. 927-934.