Lidoacin patches were developed by a doctor I think he was, for his wife's shingles pain.

I ahve used them for years. Slap on on like the ben gay pads you find in the drug store, only instead of the menthol or capsasine being on the treated site, it is lidocaine.

Lidocain will not transfer into the blood if removed in 24 hours if he has that fear.
In more aggressive treatments for RSD Dr.Schwartzman uses a lidocain IV treatment.

For your husbands knee he may have been given it for degenerative.
I save the lidocain patches for cervical hump, and low back, I use biofreeze for my knee. I also have one darvocet to take for it too. Use to have celebrex, but switched to biofreeze and worse days cut in half a lidocain patch, stays on better, last more treatments.

Just some thoughts.
Dianne