Anyone here have knee problems?

I wrecked my left knee about 14 years ago playing hockey. I tore my acl and damaged the cartilage severely. I had it scoped about 12 years ago and now i'm having troubles again with it. I go to physiotherapy once a week and had custom made orthotics for my shoes. The knee is a lot better, but i know it's only a matter of time before i have a knee replacement. I need it now, but the doctors say it shouldn't be done until i'm in my mid 50's. I'm 48 now. I have gone to specialists, orthopedic surgeons, had x rays, MRI, all of it. The phsiotherapist i see is a sports injury specialist.
All i can do now is do the physio, and maybe get a knee brace in the future. Then wait until i can get a knee replacement in 7 years.
My advice to you is to discontinue the sports that have a tendancy toward shock loads to your knees, and any other heavy load bearing. You are too young to be crippled. Believe me, 20 years from now you will thank yourself for it.
Also, see a specialist that is in the sports therapy field and follow their instructions to a "T".
Good luck.
Tom.