I experienced sciatica with both knee replacements. First knee it lasted about 4 months. This knee I am still dealing with it and it has been since Dec. I have been going to PT. Got an injection which helped a little. Doing lots of exercises. I find the thing that helps the pain the most is just walking. ROM was at 119 4 weeks out and is staying at that level. I can fully extent the knee. I would be doing great except for the sciatic pain. They seem to think it is a combination of SI joint inflamation and periformis also.