NPR intern Poncie Rutsch takes a crack at making a big sound. Meredith Rizzo/NPR hide caption

itoggle caption Meredith Rizzo/NPR

With osteoarthritis, knees become swollen and stiff, and cartilage can degenerate. Ted Kinsman/Science Source hide caption

itoggle caption Ted Kinsman/Science Source

Here's an evidence-based test with no dangerous side effects. But some common orthopedic treatments don't work. Selim Ucar/CAM/iStockphoto.com hide caption

itoggle caption Selim Ucar/CAM/iStockphoto.com

Rheumatoid arthritis is an autoimmune disease that can cause painful inflammation in the fingers and other joints. Richard Rudisill/iStockphoto.com hide caption

itoggle caption Richard Rudisill/iStockphoto.com

Swimming is one form of exercise that can help prevent arthritis from getting worse, doctors say. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Walking can actually be good medicine for osteoarthritis. iStockphotography.com hide caption

itoggle caption iStockphotography.com