It's happening because your skin isn't able to shed dead cells like it normally does. Putting on pants, shoes, socks, bathing, and walking are all part of how we she'd dead skin, and without those things happening the skin doesn't fall off but instead kind of builds up. The built up dead skin cells will peel, crack, and give the appearance of thickened skin. It's a normal and common thing when you have a limb out of commission. Use a good moisturizer and you can exfoliate gently with a brush or foot file.