I too have been following this thread and your Ol' Roo truly is a lucky guy. I think the swelling IS related to the wrap and the fact that a chicken can not elevate the foot like we could. My SIL recently broke his leg and the Ortho Surgeon would not cast his leg for 2 weeks as it can cause a very serious condition (compartment syndrome). I realize chickens are not human and that you must stabilize the leg for it to properly heal but I would try to use 2 splints (padded between leg and splint) and secure them above and below the break, firmly but not tightly. I am new to chickens but he seems to be very sweet which to me means he has at some point in his complicated life been loved and cared for. Keep up the wonderful care, the kindness and compassion you have shown to him inspires us all.