Does it hurt only going up stairs?
Do your knees only hurt (bad) when going up stairs? Are they reasonably okay walking flat?
First, I would suggest talking to a rehabilitation doctor if you have one or either that or an orthopedic doctor if you have to see a new one. Simple x-rays might address if osteoarthritis is present, but I would think given your age and prior status that it is far more likely that the problem is either in tightening of the ligament/tendons or in stability of the knee. It is really tough on knees to go upstairs. I had a lot of pain in my knees also going up stairs, fortunately (?!?) more on one side, but it was somewhat intermittent. My knees also pop, not really grind, but I could feel the rubbing of surface on surface). It felt to me like the problem was that the muscles were not strong enough to put a “brake” on the amount of bending so that the knee was bending too much when going upstairs (and also when really tired). I got a black knee brace with a hole for the kneecap from the pharmacy–I think it was about 12-15 dollars. No prescription, just a means to give additional stability to the “bad” knee. This made a lot of difference when that happened. It has not happened for the last few months as I have gotten stronger. I did not lose ability to walk ever, it just got really hard. If it is this for you, try to go up the stairs sideways (I had to switch directions every few steps to even out the work of climbing stairs) or holding really strongly to the banister or using a cane to help with stability. The first changes the direction of the stress on the knees and the latter two reduce the stress on the knees by using arms to help. By sideways, this does not have to be perpendicular to the direction up the stairs, but even an angle will help–try first 90 to see if this helps stop the knee pop and pain, then maybe 45% with turning after a few steps and stopping every few steps to “reset” your body allignment.
An ace bandage would also help stability of the knee–I just could not get it to work well enough like a knee and the tight knee brace let the knee bend better as a hinge joint, but not overbend or wobble side to side. FYI, going sidewides up the stairs is tougher on the hip joints–so it might not help since our problems are not joint related but all the peripheral nerves. Other FYIs, bending forward some helps going up stairs by putting the center of gravity of your body more in the direction you are going. (Not so much you fall up the stairs, though, just a little). I also found that walking with my feet further apart that I do on the “straightaway” helps because it gives more stability. I also found that I had to really concentrate only on going upstairs and stepping and centering right and not carry or think about other things, hard as that is. After I managed to get upstairs without feeling I was climbing Mt Everest, I learned to carry small things up in a carry bag close to the body (so less impact on center of gravity). Can you guess from this that “Miss Determined” decided that she was going to figure our how to get upstairs and tried a lot of things to do so–also that I have tried to use my physics training and knowledge in patient care to figure out ways to help the body. I am not a physical therapist, though, nor any other kind of joint specialist–just a stubborn lady who was not going to let GBS stop her or make her leave her two-story home if there was any way around it.
WithHope for a cure of these diseases and a better way to get through them until then.