I was diagnosed with it in both knees about 12 years ago, in my mid 30s. Orthopedic surgeon said i was too young to have surgery and he didn't think I needed it. I think he said they would only being cleaning up loose cartilage?? Anyway he sent me to physical therapy, I wore a knee support, stopped wearing heels all day and he told me to not do squats and lunges i think. Anyway, the pain stopped and my knee never buckled again. 12 years later and i don't have any pain in my knees. I limit high impact exercises. However, i recently started running and I've been doing a 5k training group 3 x a week with no knee issues. I stretch a lot more than i used to and do exercises specific to stretch my IT band, hip flexors. Im currently doing STS again and i actually think the muscle endurance legs is more rehabilitative for me. Find what works for you, and limit or eliminate exercises that aggravate you knee.