We had a pup in our rescue with two straight legs. I went to three vets who told me nothing could be done. This was when I found a surgeon who I now use for all of my orthopedic cases. He was able to operate on one of the pup's legs and while it was never going to be perfect, it was much, much better and Teddy Bear could use that leg and bend it. He cut and released the muscle and also had to reconstruct the knee. In the end, I adopted Teddy and he is still doing well about 6 years after that surgery. His was much more of a mess because it involved both legs and hips.
I don't know if it is the same type of thing but, I would say that IF there is any hope at all for your puppy, he would be the vet to do it. Perhaps, since you are so far away, you could have his records sent to Dr. Beale for review.
His name is Dr. Brian Beale and he is at Gulf Coast Veterinary Surgeons in Houston.
Home is their website. If you PM me, I will be happy to give you his client services coordinator's email.
He has done a few very complicated cases for YHR and I
highly recommend him.