From your description, it sounds like she may be walking on one of her hocks. Did your vet notice any issues from the pressure being placed on the hock (abrasions, etc.?). Pekins are a heavy breed, so I'd be concerned about wear and tear on the hock from that kind of use. And how old is your duck now?
If she's having a traction problem, perhaps some kind of shoe with a grippy sole would help her get around on the surfaces where she's getting stuck. There are shoes that are typically used to protect ducks' feet while they recover from bumblefoot, but I imagine they could work for other applications, too. Search on "duck shoes" and a bunch of threads will come up. I don't have personal experience with duck shoes, so hopefully another BYCer who has used them will chime in or have other helpful suggestions.
Best wishes for your special needs girl.