I'm familiar with TENS, from time in the military medical service. Our doctors used them as a means to let people manage back pain mostly, and I only remember one person who didn't care for his. It isn't something they install, in that sense, so no cutting is involved. TENS means transcutaneous electrical nerve stimulation, and it works by an electrode sort of glued to the skin- something like the patches they put on you for an EKG. The site for the manufacturer is www.tensunits.com and it's loaded with info to answer all your questions. You can even email the company with questions if needbe. I did when I was first approached by the doctors to look into purchasing one for a patient, and they were very helpful.
A TENS unit works by basically overstimulating the nerves that are causing you pain, which causes them to shut down temporarily. How long they stay quiet is different for each person, but as I recall most people said it lasted pretty much a day. It wasn't always able to totally eliminate their use of pain medications, or muscle relaxants, but it did cut out a lot of it and the amounts they needed way down. The best thing about them is that they aren't addictive, you can decide when and how much you need, it's under your control once you learn to use it. They don't leave you drugged and groggy, or knocked out like the high powered pain relievers do. They don't upset your stomach. The main no-no for them is they can't be used if you have any kind of arrythmia of the heart, or a pacemaker, and not on the head or neck. There are a few other conditions, like pregnancy- but I don't think you have that concern. I'd say it was worth a try. If it doesn't work, though it should, then you are no worse off than you are now. Your insurance should pay for it, workman's comp does, and of course the VA and military do. So I say, check it out and give it a try. They even used to have rental units for that reason, so you could try the different versions and see.
retired AF, nurse