I think you are referring to your shin? It is very common for the nerves there to be damaged during TKR, and then have to heal and regenerate. The feeling is NOT pleasant. Nerves regenerate very slowly, but over time your brain accepts the feeling and it becomes less noticeable.

One thing does concern me though - you say " or sit at a desk for hours" - at this point in your recovery, whenever you are sitting for more than a few minutes, you ought to be elevating and icing your knee. @johnbishop can tell you about the advice he got from his doc after TKR.

Have you returned to work?
Sue