I saw your precedent post about your 14 years old horse. I do think that three things can help him about his pain and inflammation.
First, you can massage it with a heating cream before riding (Please, do not touch your eyes just after or use gloves when you apply the cream or it's going to burn quite bad!)
Secondly, a cure of joints supplement with MSM, glucosamine and chondroitin would be great. Harpagophytum is a nice alternative (and a little bit cheaper than Chondroitin : it is a natural plant and it helps joints a lot ).
Third, I do think that an application of clay would help him a lot ( I have a preference for the Kevin Bacon's 'Sea Clay but you can find many others in your favorite tack shop).
Maybe the farrier could help him too, with special shoes (Egg shoes). I used to ride an old horse with stifle lock problems and those three "tricks" helped him a lot!
PS: I just saw this equipment on the internet, I didn't try it but i do like the concept : http://www.icehorse.net/products/ice-horse-stifle-wrap