Well I havent tried it myself. Ive looked into it as well for crohns.
One thing that appeals to me is its natural.
Hard core drugs will most likely cause organ damage over time, pot not so much.
I feel that because it is natural it would be the first step to try, why go big, and risk problems later.
Not to be a jerk, but what about losing some weight, that might take some stress off the knees?