Hi, I just looked at your blog.
Have you tried resistance exercise? While she is lying down, press up on the bottom of her pads and see if she'll push back. If she keeps her leg bent, try tickling between her toes until she kicks her leg stiff, then press up on her pads. This works with rear paralysis, I haven't tried it with radial nerve damage.
In your photo, is the bent leg the one with nerve damage? You said your are doing PT every day. Are you working the leg through the full range of motion? You want to flex and bicycle the leg to keep the tendons/ligaments/whatever from shortening. You do not want her to develop a contracture.
It is possible to splint radial nerve damage for part of each day.
Here are a couple of photos.
The caption reads:
Orthotic for a Labrador Retriever with partial radial nerve damage and subsequent knuckling of the paw (22a). The dog was not able to fully extend its carpus. This splint was worn 10 hr per day with excellent tolerance. The goals were to prevent flexion contracture of the carpus and to prevent skin abrasions. Vetrap was placed over the splint to prevent the splint from slipping
This is the article but you have to register to read it.
http://www.ivis.org/special_books/Braun ... m.asp?LA=1