Sometimes with the TENS unit it is about finding the right placement of the electrodes. As long as it is not causing more pain I would suggest trying this again. I think I was lucky that the physical therapists got the placement right for me in therapy and then when I got my own unit I was able to use the same locations for relief.

tDCS is not the same as electric shock...so that is still something that I would suggest looking into. It doesn't go on the RSD areas and has no history (to my knowledge) of making RSD pain worse. It's much cheaper than even what my copays/deductables were for even the lumbar sympathetic bocks that I got (only $300 total for all the equipment without insurance paying any of it). If you have tried all the other options then this is definitely worth a shot...especially before doing anything invasive.

I understand your worries about the knee surgery. ANY sort of trauma to any area of the body runs the risk of making the RSD worse or causing spread. It doesn't happen in every case but it is a risk that you need to be aware of when you make any decisions about your healthcare. So before having any surgery it's important to weigh the pros and cons. At some point, for many of us, there are times when you will NEED surgery or some sort of invasive procedure and that is just that. If you NEED the knee surgery then just do some research on what sort of things they can do to prevent spread. I would start by posting on here (seperate thread) for advice on this. I don't remember exactly what the process is myself but I know I have seen people on here give advice about it.

Have you gone through a good physical therapy program? Physical therapy was the single biggest thing that has helped me to at least get back the function...which has helped my mental health a great deal as well. It's hard...but if you can get a good therapist it will be worth it. I did at home physical therapy this last time (where the therapist comes to your house) and it was a godsend. Worked out well in large part because everything that we did in therapy was stuff I could do on my own even when the therapist wasn't there. And I did those exercises every day. It was a long, painful process but it was worth it I think. I haven't had a lot of success in getting the pain level down but I have learned lots of ways to cope with it to help me get through all this and get a large amount of the function back.

I really hope that you are able to find something that works for you. Take care and good luck.