I tore mine in 1993, climbing a hill that I didn't make, no crash just stopped put my leg down rolled the bike back and hyper extended the knee. I knew I was in troupble got back to my truck, in pain I might add, I felt a pop, then I knew I was in trouble. By the time I got home I was sporting a soccer ball in my knee. They couldn't do anything but remove the fluid till the swelling went down. In the end I didn't get it replaced and in hind sight it was a bad idea, now it will be a full knee replacement. I went for many years where just rolling over in bed would cause it to pop out, I got very proficient at popping it back in. Now I think ther is so much scar tissue that it doesn't pop out any more but it gets sore very easy and I think it's too weak to really do its job, its loading up the left knee to compensate.
If I had it to do all over again, I would have had it fixed right away because I'm now paying for it everyday.
My son had his blown out when he was riding 80's, they didn't want to do anything with it until he quit growing, afraid that it would stunt the growth in that leg. When he quit growing we had it done, he did his physical therapy with a personal trainer, he was back riding bikes in 3 months and racing in 6 (Dr. gave the OK, he also said that they heal much quicker but they want to make sure parents aren't pushing kids to soon and some heal quicker and are more dedicated to the rehab.
Good luck
Don