Could Pain In Buttocks Radiating Down The Ankle Be Due To Sciatica?

I hade a knee replacement 4 years ago and after 6 months of rehab it seemed to me my leg that had the new knee was a little bit longer. I noticed it because it seemed like I was alwase standing with more weight on my right leg, which is the leg that had the new knee. Now I am having a severe sciatica nerve pain that starts in my butt and goes all the way down to my ankle. Could this cause my sciatica pain?