I am 48, coming up on 49, and had my right knee done 2015. Speaking for myself, my knee feels great after having it worked on. Mine recovered well. I really took it pretty easy during physical therapy and gradually worked up to mediocre squats (back issues). I can do a great deal of leg presses and leg extensions without any issues.

A friend end of mine , she has had her meniscus done twice and just recently had her knee completely replaced for the second time. I really think it is up to the individual body to some degree. Hope that is more encouraging for you.