Dear Mrs. Ambastha.
Sorry to hear your plight and torment all these years, especially the failure to relief from all modalities. I think this could turn out to be rheumatoid in nature. Have you undergone blood or x ray
investigations? If so I'd like to know the reports. If not then I'm again sorry that you were never definitely diagnosed. The condition of your leg is called arthritic varus deformity
and if not properly diagnosed and treated can turn disastrous.Same goes for other joints too. So I'll suggest you first concentrate on reaching a diagnosis, then arrest the condition at the said stage, then treat the cause and disease. And yes as you said only single knee replacement
is not an answer..but an incomplete answer. By which I mean you would eventually land up deforming the other knee as well. But knee replacement is a fine option to think of..and a definitive one too.
Good luck and remember..always follow evidence based medicine.
Have a nice day.