What are possible causes for severe swelling in foot up after having total hip replacement?

HIP REPLACEMENT. Hip replacement is major surgery and takes many hours to do it. Severe swelling after or is due to traumatic surgery and not well established circulation yet. They have to use crutches, undergo intensive physical therapy to properly walk again.
Support stockings. Possible cause is improper lymph drainage. This can be alleviated by wearing a support stocking. I would discuss this with your surgeon to rule out other possible causes.