I've got a similar issue whereas my girl hawk I rescued other week, we tethered her down for first time in her life, previous owner had a whim bought a bird, then got scared.
Any way the new anklets were running her rear leg, causing swelling, our fault, we replaced the anklets with pig skinned lined anklets washed her legs prep h n F1 cream seems to work.
Question folks his will this swelling have caused any tendon damage joints damaged ect, being as she'ss really underweight, she 3lb 4oz at minute reckon fat weights up in 3lb 14oz or may hit 4lb,she is very tall hybrid or Eagle cr