A TKR is a very traumatic event. One's skin is cut open and the tibia and femur are cut to remove arthritic elements and to allow the implant to replace the cut bones. If the surgeon used a tourniquet, that can cause pain for a number of weeks. If your surgery was traditional, the surgeon also cut the tendon and muscle and had to sew them back up at the end of the procedure. More trauma.

That is why some surgeons have changed recovery procedures to rest the first few weeks while icing to help the inflammation to subside. Then start PT. My surgeon had me resting the first two weeks before starting PT at the PT facility. Similar to the new Quiet Knee Protocol from the Hospital for Special Surgery.