Today he'll move easier on two artificial knees, implanted 19 months ago.
If Maria's leg becomes infected, the artificial knee may have to be replaced.
The charity wants to ensure that the artificial knees being implanted today can last 30 years or more.
As a result, the worldwide market for artificial knees is around $600 million a year and growing.
The artificial knee allows a person to do ordinary daily activities with less pain.
The police discover a skeleton on his property with an artificial knee dating back to the '60s.
Here's this kid who's already got an artificial knee and a replacement eyeball as a result of injuries.
Hobbled by an artificial knee, he was thrown out at first.
The captain wondered whether the man had an artificial knee.
He had two artificial knees and a worthless right hand.