Hand clawing is often associated with Thoracic Outlet Syndrome also.
Some with TOS were mis dx'd with ulnar or carpal tunnel {or other tendinitis injuries} and after those surgeries they still had sx - because the real injury/compression is up in the brachial plexus area of the neck.

HubbyWithRSD,
does he have a tight neck and or neck and shoulder pain along with the other symptoms of ulnar and carpal?
there is also whats called a double crush and triple crush - where there is a compression at the BP, the ulnar and the carpal.

Just wanted to mention this in case you haven't heard of it before.
What was his work injury?

We have a Thoracic Outlet Forum here also.
many do have RSD with the TOS and work comp claims.

if you think you might have TOS we do have many threads on self care and "helps" and meds.