Nerve block surgery for faulty wrist replacement ?

Hi,
My partner is 34 and has Rheumatoid arthritis and maybe lupus as well. She dosn't really show and signs of Lupus at the moment, and with all the drugs she is on, she is generally in good health and able to live a normal life.

She had a artificial wrist replacement about 5 years ago which initially didn’t heal very well.
She now gets stabbing twinges coming from the wrist area quite frequently, sometimes even when she isn’t actually moving her wrist.
Repeated X-rays and numerous consultant consultations have decided that the joint maybe rubbing against some nerves, but is basically ok even though from the X-rays it looks like it has gone in not quite right.
All that she has been offered by NHS consultants is a fusion which would be very invasive and rather final.
I have asked the question that can’t you just identify and cut the nerves that are causing the pain and the consultant has said that he doesn’t do that and can’t explore this further and can’t refer her to a consultant that can.
He also says that nerve block surgery works well for some joints, but it isn’t practiced as a pain blocker for wrist issues.  
Myself, coming from a high precision engineering background is finding it very difficult to understand some of the things that the consultant is saying.
When he said it was the middle part of the joint which was probably rubbing (which isn’t apparently bonded in the bone), I asked can’t this be removed and replaced with a modified/machined one ?
He laughed.
I don’t know if this is because medical people are not aware of the sort of things we can achieve with plastics, composites and metals or If I’m being rather simplistic about the whole thing.

Any suggestions or help would be appreciated.
Thanks
Jason