You might consider studying MSM vs. DMSO. It's the part of DMSO that works and doesn't wear off as quickly as DMSO, plus you don't have the odor of breath and skin. It's something I have used on our 17-year old cat when she began having a hip problem that made her limp very badly and hang out close to the ground. After only 5 days on the MSM the limp stopped and she was jumping up stairs again and her usual playful self.
Having dealt with rheumatoid arthritis myself for 25 years I do understand chronic pain and the overwhelming desire for relief. You might want to read this article about MSM for horses. Technically, of course, you can't make any claims for humans with a supplement.
The quality source and reasonable priced product I use is the Nature's Sunshine brand: http://www.theherbsplace.com/MSM_p_516.html