Science fiction or not....a TENS machine works for me and has done for the last 11/12 yrs. At the time I had torn a rotator cuff and went to the local physio to work her magic of massage, taping and TENS, then I was just returning every second day for TENS and she suggested I buy my own machine as it would be beneficial long term, not only for that shoulder but I have arthritis in every joint in my body (diagnosed by an Orthopaedic surgeon).
It has been 'the' greatest thing for pain relief and I wouldn't be without it and would buy another in a heartbeat if it stopped working. I also have fibromyalgia and some neuropathy, so pain is a constant in my life.
I purchased the TENS online from a medical supply company and can't remember how much it cost but it has more than paid for itself, when compared to return visits to the physio.
Just had a quick look on ebay for you and this is very similar to mine <tinyurl.com/2w6bd5xm> the case is a different colour etc but you'd expect that in 12years. Mine is powered by a 9v battery and it lasts for a long time...the last battery was more than a year old.
It's not something I would have bought without the suggestion of the physio, so I hope some of this helps?
Over a lot of years, I've had many Cortisone injections with mixed results and really I dislike what it does to your body, but when pain is so bad you are prepared to give anything a try...trust me I've been there too! So for me TENS is the drug-free alternative that really works, hope you get similar results.