I don't know about that, but there are balance ball chairs out there that help relieve back strain and are actually recommended by physical therapists and chiropracters. I used to work with a bookeeper who used a balance ball part of the day when she needed a break from the office chair. They look something like this one:
http://www.gaiam.com/basic-balance-b...efault,pd.html
You can google it and compare prices. Good luck