There was an interesting article in the April 2009 issue of Practical Horseman magazine (page 80) about a dressage rider that had to have back surgery due to disc problems. She had a new procedure called total disc replacement (TDR). The article stated that this was FDA approved in the US in 2006, so not all doctors may be using it. Just thought I would pass the information along - might be worth doing some research... Good luck.