> It's essentially like localized steroids to just the joint- killing off the immune cells causing inflammation.
Are you confusing osteoarthritis with rheumatoid arthritis? I didn't think the pain of osteoarthritis had anything to do with the immune response. You've literally got bone rubbing against bone. It's not going to feel good.
Both OA and RA involve some inflammation (-itis means inflammation). RA is more T cell driven inflammation (and clinically visible) while OA is more macrophage driven. Mechanical wearing still makes the joint unhappy at the cellular level- you just don’t see it big and red as a symptom like in RA.