Raelynn has Cerebral Palsy, which often comes with things like spasticity and clubfoot. Raelynn wears AFOs to help with that.
Raelynn recently had hip surgery, and her legs were casted in an A-frame in order to prevent her from undoing part of her surgery. She was casted all the way down to her toes because she wouldn’t be able to wear her AFOs (since the cast would have gotten in the way).
The primary purpose of the cast was simply to allow her hips to recover from surgery, but they definitely also helped with her range of motion, as do her AFOs.