HELP PLEASE.

Has anyone had trouble with the ball joints on the 2003 going bad for no apparent reason? In June I had to have the upper right replaced, the whole inside (facing tire) half was gone! Now I have to have the lower left replaced. I don't off road, our highest speed limit here is 25 mph (LOL), and it only has 21,700 miles on it....10,000 of which were on it when I bought it 2 1/2 years ago. Can anyone shed some light as to what might be causing this or has anyone had similar problems????