It looks like a very bad case of scaly leg mites. Has it been like this long? I would soak her legs in warm soapy water, and take a tooth brush and gently scrub her legs and feet to loosen the scales. Then apply some castor oil, vegetable oil, or vaseline to the legs and rub it into the scales. Castor oil is the least messy. Repeat at east once a week, and after several weeks the new scales should start growing. There are other skin conditions affecting chickens such as fowl pox and tumors, so here are some links to read: http://www.the-chicken-chick.com/2013/03/scaly-leg-mites-in-chickens.html https://www.backyardchickens.com/t/33903/scaly-leg-mites-need-best-easiest-quickest-solution-scaley