Splayed legged budgie with pressure sore

by Erin
(USA)

I rescued three splay-legged budgies about a year ago. They are really healthy and active. I set up perches along the side of the cage so they can perch with one foot on the perch and with the other foot they hang on to the bars. But one of them has devoloped a pressure sore on her foot. I've tried soothing creams and sprays, and they have rope and natural wood perches in their cage, but it hasn't gotten any better.

What kind of treatment would this require?

I would appreciate your advice, thank you.