I would look into a payment plan to pay for the surgery.
My dog Smokey had a torn ligament as well and since he was favoring the other leg his bad leg started losing muscle mass and started to develop arthritis. Getting the operation was the best thing I think. All things considered I don't think it was *that* expensive (about $1000 if I remember correctly). He was not even 3 when he had the surgery and he is in good health otherwise so I couldn't imagine him limping and in pain for another 9 or 10 years...

...another reason i wish i had signed up for pet insurance when he was a pup....



best of luck

-amanda