I'm sure I'll get blasted for this, but I feel it saved my hike very early on. I used a product called DMSO (Dimethyl Sulfoxide). A trainer from one of the Florida Sports teams told me about it about a year before my hike, then I saw it mentioned (maybe here) a couple of months before I left for the hike.
I have two rotten knees from high school and college football and a few other stupid things from my youth. Point is, they are old injuries. The trainer told me they use this on the athletes immediately following a joint injury and it seemed to work very well. I bought a couple of bottles and took one with me. Before I got to Dahlonega my knees had swollen to about twice their normal size and become very painful. I started using the DMSO and took two zeros in Dahlonega sitting in a hotel room with ice bags on my knees.
When I got back on the Trail I went slow for a couple of weeks, but I went. After a month of using the DMSO twice daily, my knees felt like they did when I was a teenager. I used the product a few more times over the course of the hike on a twisted ankle and again had excellent results. Here is the really great part; my knees don't hurt anymore. After 20 years of pain, they are for the most part pain free. I can strap on the pack and hike as fast and as hard as my lungs allow now. There is a big trade-off concerning weight. Because it is a solvent, it has to be carried in glass. Plus, it takes pretty thick glass to survive in a pack. Well, my pack anyway.
There
ARE some very serious issues with this stuff; your skin has to be very clean. Read about it before you use it, but if you do decide to use it I think you'll be pleasantly surprised. I ordered mine from
here.