Rob,
When I injured my knee, it was initially diagnosed by the ER doc as a medial collateral ligament tear. He demonstrated this to me by bending my knee in way God did not intend...
I went to the orthopedic surgeon 2 days later, and he said, yeah, you tore your ACL as well. He showed me this by pulling my lower leg in a way God did not intend.
I went and got an MRI a few days later and went back to the ortho's office. Two doctors read the MRI and said, WOW, you really did a number on your knee. I tore the ACL completely, the MCL partially, and the meniscus in multiple places. When I eventually had it fixed, the surgeon replaced the ACL with an autograft and the MCL stitched with a few stitches/sutures. And he snipped out the parts of the meniscus damaged.
I'm under the (likely mistaken) impression that meniscus tears aren't as big a deal (those are the kind of things that result in athletes having arthroscopic surgery and returning a few weeks later), but ligament replacement is a big deal. Steve, with his abundance of experience (he was a skiing stud, unlike me, I was a mathematics stud, which is not to underscore his scale on that latter part, he'd probably top me there, too), could probably speak more knowledgeably about this. I had ACL reconstruction with an autograft, the surgeon made a new ACL from a hamstring graft. Two other friends told me to go with an allograft, but I wanted my surgeon to do what he wanted and recommended, which was the autograft.
My knee never wakes me up. I limp in the morning, until it loosens up. I am never pain free, but it never rises very high. The reason I posted this thread is I don't want to spend 15 years limping half the day, if I could short circuit that. I have another friend who had knee replacement, he's younger than me (I'm 55) and he said he wished he had done it sooner.
Feel free to email me and I will send you my cell number if you'd like to speak about it. As I mentioned earlier about Steve, talking with someone is very helpful, imho.