No sign of a brain tumor or something pressing on the spinal column? Nerve damage or a stroke??

Is she in any distress or pain? If not, then having her as a house hen shouldn't be a problem, she'd probably be pecked to pieces or go into a decline and starve if she were put outside again. If she's happy, not in pain and doing everything else that chickens do, then I'd say you've got yourself an indoor egger. Give her a week or so at least, just in case it cures itself. I'm not for unnecessary suffering in animals but everyone deserves a chance.

LTS