I think it is important to discuss this in a pinball forum, we as players stand for hours in front of these pinball games and I for one want to be comfortable and pain free and enjoy the game and play it as well as I can. There are older players on here. I don't want to have to sit on a chair and play either.

I was taking Vioxx and it was great for my knee pain, could dance and all while taking it. Vioxx was discontinued because evidence showed it was strongly linked to causing strokes and heart attacks. Supply was stopped and the drug banned real quick, there was another similar drug pill joint treatment also discontinued over this.
Its seems like, as soon as a good drug happens, the government stops it.

I have a similar osteoarthritic knee problem I need to have sorted eventually, in respect to getting my knee joint repaired. Its almost too far gone. I am told I am too young for the replacement because it would need to be redone in 15-20 years, the other issue is over time, treatments get better and having the original knee bone in place still is preferred to get such treatments. Likely too that metal type replacements wear time could be extended by better engineering and build. We can send men to the moon...as they say.

I think getting the replacement younger would mean the body to could adjust to it easier, as some bone around the metal parts still grows and repairs, the older you get the slower the bones repair and things take.
Usually because we put uneven pressure on the 'good knee' we then put our uneven wear on our hips as well.

The promising osteoarthritic treatment is using adult stem cells and biopsy tissue cultured to grow knee cartilage in the lab on a matrix of protein shaped like your own knee joint, genetically keyed to you, then implanted (or glued in place) on to knee bone.
I am sorting of holding on for this kind of treatment to mature.

What I need to do now is loose weight by eating better foods and less crap, no carbonated fizzy drinks and exercising in water and on a push bike regularly, low impact.
Other than that and wanting to play pinball, maybe design in a chair or some support, built into the game.