Hey what a neat coincidence...I just started Alan Fraser's book "The Craft of Piano Playing". He merges ideas of the Feldenkrais method with piano playing. Anyhow, he writes about the skeletal structure in your hand and writes that the bones need to be aligned in the most optimal positions for strength and movement; when your finger knuckles collapse, the skeletal structure is out of alignment and weight distribution is thrown off. Fraser gives exercises to solve this "collapsing" issue in particular.
Fraser also points out that he noticed many collapsing thumbs in students--so pay attention to that.
Like I said, I just started this book so I can't tell you if the exersices are effective. However, I am so far intrigued by his ideas, and have heard good reviews so it's possibly a good book to check out.