Joint mice?

Has anyone had a cat diagnosed with joint mice, mineral deposits in a
joint? As I posted in another thread, our 8 year old cat was having
trouble climbing stairs and after a series of x-rays the vet says she
has "joint mice" in her kneecaps. In people I think this can be fixed
with arthroscopic surgery but he said in cats knee surgery usually
makes things worse. He said it is often caused by trauma to the knees
(which I can't think how she would have had) or sometimes it just
happens as a cat gets older. Anyone have any information or experience
with this? He said it is controlled like arthritis, with glucosamine
and anti-inflammatories. I just hate thinking our cat is only eight
years old and at risk of eventually going lame.
-yngver