Hello @babsarmour, Welcome to Connect. You will notice that we moved your post to an existing discussion so that you can learn what others have found helpful for sleeping after a total knee replacement. If you click the link below it will take you to the beginning of the discussion where you can read through the posts by others.
--- Trouble sleeping after TKR: What helped you sleep?: https://connect.mayoclinic.org/discussion/trouble-sleeping-after-tkr/.

I'm normally a side sleeper and it was more difficult since they want you to keep your leg straight and it's not exactly comfortable for me. I did use a small pillow between my legs which helped some. Here's a video that goes through some tips and a good explanation -

I did not sleep well for almost 3 months after TKA. I also had peripheral neuropathy in surgical leg. My surgeon started me on Gabapentin which did help with sleep and neuropathy. It is a tough recovery but hang in there. I am now 7 months post op and glad I had surgery done. Sending good vibes your way.

Maybe try a king size pillow between your knees for side sleeping. This is what I did, and still do. Shorter pillows won't work because your feet come together, putting the knee at an awkward angle.