Okay, placement for Lidoderms is really critical for success.

For your back it is pretty obivious. I'd put a whole patch across your lower back just before the crack of the buttocks. Clean dry skin. They tend to move around. If you perspire alot, it may need tape around the sides. If after 3 days you get no relief, raise them up about 2 inches.
You have to find the "right"spot.

For the knee, I use 1/2 patch behind the knee, on the thigh side, on the back of the thighs, going across just above the bend. There are nerves in there that the Lidoderm numbs up. If you have pain in the front of the knee, don't put it there.
For the front of the knee you can use Salonpas patches. These work very well for me. I often get pain on the inside of the leg just below the knee. I stack 2 of them there. After gardening I sometimes need them.
These are great for those other spots:
http://www.salonpas.us/salonpas.php
Use only the ones that have methyl salicylate in them. (unless you are allergic to aspirin?) They make several kinds. So read the labels carefully. They are really good for tendonitis too.
I buy mine in bulk at Costco. But RiteAid and Walgreen's have the smaller boxes -- 40 for about $4.00. Once opened, put the remaining in a Ziploc to keep fresh. You can cut them too.
They will work on the back, but are less effective where there is alot of flesh between the patch and the pain site. So feet, knees, fingers, work better. I have used them on the back however for emergencies. They do have a scent of wintergreen, but one gets used to that...it is a small trade off for relief!

I use them just about every day either for my feet, knees or hands. Something will always be bothering me. ( I have severe osteoarthritis).

I think the interventions you should be looking at are the ones for inflammation.

Lidoderms need everyday use for at least a week. Here and there is less effective. I had a total remission of severe meralgia paresthetica in 2 weeks with them. That was unexpected, and taught me alot. Using them irregularly doesn't turn off the nerves the same way.