Do you have pictures of the filly -- that would help.
A hip lock is a difficult birth on the baby (as well as momma), but it sounds like you acted quickly and brought that little one safely to the ground! KUDOS for your quick thinking!!
With a difficult birth like that, and the swelling, I would immediately contact your vet and get her started on some prophylactic antibiotics. Joint ill in a newborn can be very dangerous, and I'm sure the swelling is from the gentle pulling, etc, But, there is no use taking a chance with a newborn.
I truly believe, that if you can get her up nursing, and allow her some freedom of movement, her little legs should gain strength and begin to tone up and straighten up. She may have displaced her little hip -- or it's sore from the pressure of momma pushing that hip bone into momma's hip bone.
The key is to make sure she's nursing every hour -- don't let her decide to sleep instead of eat. This first day or two is important to get her colostrum level up, and give her the strength to get moving around on those legs. The crossing of the legs is not that worrisome to me, as all newborns do some very strange things as they "get their legs under themselves" -- so I think with a bit of time (a couple of weeks at least) you will see a magical change in her.
I had a 28" mare who produced a filly who was 21" at birth. The greatest problem was milking that momma and feeding baby for 4 days, until I could teach that little one to kneel to find the milk bar. But, with time she figured it out, and all was well. Her teeny momma had an udder like a dairy cow, and was hanging so low, I could barely teach the little one to almost "go to ground" to find the nipples.
Pictures please, and let's give this little one a couple of weeks to exercise and strengthen her muscles, joints and legs before you get to worrying too much.