Melody - I have no knowledge of a tens unit but I wanted to say that if you have a choice, don't put the electrodes on top of the foot. I had some pain treatment from a podiatrist several years ago and he was adamant about not applying this gel on top of my foot near the base of the toes which is where I was then having the most problems. (I think it was associated with ultrasound but it WAS for pain relief, strange I know)

Try the "toughest" part first, what about his heel or the ball of his foot?

Good luck and keep us posted. I was also interested in a tens unit and wondering if there was any long lasting benefits. Seems like it might "reprogram" the pain paths that I read about occasionally which say that once you have the pain, your memory of the pain may keep it going even if the source of the pain is removed.