ABC 33/40 - Birmingham News, Weather, SportsNearly 1 in 20 U.S. adults over 50 have fake knees

Want to find America's weak point.  Check out the knees.

Some staggering numbers just released on how many Americans already have artificial knees! Nearly 1 in 20 of U.S. older than 50 already have had the operation.

That's 4.5 million people.  Why is the number so important?  It helps doctors assess future needs for health care resources.

Knee replacement operations are on the rise.  Doctors believe because of the obesity epidemic and amateur athletes who don't adjust workouts to spare aging joints.