Had a tiny runty chick hatch last weekend with the toes all curled up on both feet. Found info here on splinting the toes into a normal position with the sticky end of a band-aid & a tiny piece of thin cardboard cut into the same shape, (per instructions on the thread). Took the splint off today - one foot was mostly out anyways, the other about half - they were only on since mid-day Tue, and VOILA!!! Little chicky is walking completely normally!!!
Your bird is much older, but still young. Perhaps this may still work, in a modified form. Another post showed a foot-shaped cardboard cut-out that another member used to correct this. Sounds simple & easy - I'd say its worth a try!