One of my RB piggies had her back left leg amputated 20 or so years ago following an infected rat bite - very much a last ditch attempt to save her life which thankfully paid off. The leg was taken from the hip joint, I believe (I was a bit young but certainly there was no stump to speak of).
She was in the prime of life when it happened and lived for several years post-op. She walked by kind of bouncing off her belly and actually managed an incredible turn of speed with the proper motivation (dinner time, of course!). She spent the rest of her life participating in and enjoying the same activities as she did before, and managed to keep up with her siblings incredibly well. We did make adjustments to their cage/run (beyond the security measures added following the rat incident) so that it was easy to navigate and that there were no jumps, stones or edges which could potentially hurt her, as she didn't have quite the same level of control as she did; in the end though she never sustained any injuries to her left side despite the wobble.
Obviously this is just one anecdotal experience and, as I say, definitely not Plan A, but they can be remarkably resilient creatures. Of course the surgery carries its own risks and might be costly, but in our case at least it was worth giving her that chance.
If one of my pets needed an amputation, we'd exhausted other options first, and we could afford it, I would most likely choose to do it again.