
I can understand how frustrating this has been for you. But, surgery isnt 100% guarentee. Even though the surgery was not a success when this vet did it, it was a good thing to go to another. But I dont know if you could actually sue the vet. The vet performed the surgery, and you paid for that surgery, not actually the cure. I really hope, I am not sounding rude, as my intentions are not to sound rude, just giving straight facts. But it would be good to file a complaint. There are also sites that you can go to, that you can "rate your vet". Be careful though, if you are going to post anything, as it can be used against you. Keep everything to the facts, and try to leave emotions out of anything written. Say things like "on such and such a date, my dog had surgery and so far I have not seen improvement, but a decline in patella function" instead of "this vet is a quack, he cant even do a surgery right, my dog isnt improving!"
He shouldnt have had you come three more times, and charged you all that. Does he not have a recheck fee? A lower price when you are bringing the dog in for the same issue?
But good for you to get another opinion from another vet. Hopefully, this vet can get your dogs legs better.