Expert Q & A

Straight answers to interesting questions about OA of the knee

Joanne Jordan, M.D., is director of the Thurston Arthritis Research Center, University of North Carolina in Chapel Hill.

Leigh Callahan, Ph.D., is assoc. professor in the departments of social medicine, orthopaedics and medicine at the University of North Carolina.

Q: I’m thin, active and healthy? Why do I have knee OA?

Dr. Jordan: We are looking for new answers to questions about what causes OA. And we are finding some surprising clues. University of North Carolina researchers have shown that people with higher lead levels in their blood were among those most likely to have more severe osteoarthritis. Up until the 1970s, lead was found in many products, such as gasoline, indoor house paint and even cans for food.

Once you're exposed to it, lead goes into the bones where it can affect production of blood cells and absorption of calcium. We're starting to get some indication that it may affect joints as well, but that's still uncharted territory.

Q: Why can I ride a bike 25 miles with no knee pain, but I cannot run?

Dr. Callahan: Physical exercise is great for people with OA, but it needs to be the right type. Riding a bike—and even better, swimming—strengthens muscles and improves circulation and flexibility without putting strain on the knees, as running does. These activities not only do not aggravate OA, when done regularly, they are pain relievers.

Publication Review By: the Editorial Staff at

Published: 23 Feb 2010

Last Modified: 09 Oct 2014