So I have an interesting post-script to this thread. During the course of this thread, my knee pain was nearly 100% eliminated by placing a small pad under my first metatarsal.

Well.

I have been upping my mileage to train for a half marathon, and was very worried after a 9-mile run. My right knee was in intense pain from 5 miles on, and I was concerned 13.1 just wasn't going to be possible.

Nonetheless, I scheduled a 12-miler with my running partner and crossed my fingers for the best. Right before the run, I decided to check the pads I'd put under my insoles, and -- lo and behold -- the right one was missing! I'd been fiddling with the shoes and forgotten that side. I put a new pad on, ran 12 -- at a brisk pace! -- and had no kneed pain at all, and felt great the next day! (Last August, pre-padding, my knees hurt so much I literally had to crawl up stairs after my first Olympic Tri.)

Maybe it was just my body adjusting, but, given my 20 years of fairly persistent knee pain, my bet's on the Morton's Foot diagnosis and subsequent insole changes.

Just thought I'd share.