Has the vet taken x-rays? If so, your vet can probably send digital pictures to an orthopedic specialist as a consultation. The other thing that is always possible is to call WSU and ask for the names of orthopedists in your area. There is a veterinary orthopedics professional association. They didn't have a "find a vet" link on their site. It may be possible to call them for referrals, as well.
From some skimming of information that's around, atrophy could be related to nervous system issues, a spinal compression, or a fracture.