I know Im not around much but here's my two cents!

Eli had a torn ACL two years ago, had TPLO surgery. We did try to not have surgery for about a month prior. It was a partial tear, so he would use it and then not, back and forth. Ultimately, with the risks of arthritis and having it completely tear down the road, and considering he was 4 at the time, and not to mention hes a good 70 pounds, we went with the surgery. I have heard of smaller dogs not having the surgery, because with their weight it usually will heal enough.

If nothing else, I wanted to reply to the previous posts about Dasuquin. LOVE LOVE LOVE it for Eli.
He has some issues w/ arthritic degeneration in his spine (abuse from previous owners) which limited his range of motion and lead to severe muscle spasms.
We had him on Deramaxx for several years because of this, having his liver levels tested routinely (steroids).
When we had the TPLO surgery done, the vet (diff from our usual vet) recommended we use it, and that it would help w/ the ACL problem.
He's been taking it ever since, and was taken off of Deramaxx and hasnt had any muscle spasms since.
We buy it on Amazon, cheapest I've found it. (Dasuquin w MSM is what we use)

Good luck!