Oh nopoor buddy. I'm not an expert, but I've dealt with a few injured frogs. Do you have a quarantine tank you could put her in? Put damp (not soaking wet) plain paper towels on the bottom, a soaking dish, and a hide. Cover 3 sides of the tank, that will help ease some of her stress. For the frog I found, her legs were severely injured so I ended up having to tong/hand feed her so she didn't move around too much.
Is there any broken skin? And can you maybe get a more clear picture of the leg? Frogs are pretty resilient so your main goal now is to make sure she's comfortable so she can heal.
I hope that helps, I don't own any whites, but this is pretty standard for most frogs. Good luck to you and your buddy!