If your bird is permanently and severely handicapped, consider moving it from the large aviary to a roomy cage, where it will not be physically stressed trying to reach food, water and perches. If possible, cage the handicapped bird with a gentle companion or place the cage near the aviary so the handicapped bird has company. Regardless of where your bird lives, it needs special facilities. Most of all, birds with handicapped legs or feet need a variety of perches that are easy to grasp. Natural tree branches are particularly good for this purpose because bark is easy for disabled birds to grip.
Branches also provide natural give when birds land.
Also try open wicker nest baskets and small platforms for the bird to sit on. If your handicapped bird lives with other birds, provide extra food and water dishes, since handicapped individuals do not compete effectively. Try a variety of dishes, so you can identify the types your bird uses most easily. Any finch with handicapped legs or feet needs frequent nail trims, because nails on disabled limbs may receive little natural wear. Long nails can easily catch, causing further injuries.