Here's an all-too-common situation. You develop low back pain that lasts for more than a few days and you're uncomfortable enough to go see your primary care physician. He or she tells you it's not clear what's going on and sends you for a magnetic resonance imaging (MRI) study of your lumbar spine.

The numbers of individuals undergoing total hip replacement and total knee replacement are increasing significantly.1 Annual rates in the United States for total hip replacement have increased more than 50%. In Denmark, rates have been increasing by 30%. Annual rates in the United States for total knee