Good point. The exercises they give you to do at home are extremely important to a successful TKR. Do then 3x day followed by ice and elevation. It might help to take pain meds an hour or so before doing the exercises.

I'm generalizing, but most people who don't recover well from TKR simply don't do the required post-op work. The surgery is the easy part. And I'd say the first month immediately after surgery is the most important.

Please understand that extreme or sharp pain means something is wrong, or being done incorrectly, and should be stopped immediately. With bending and straightening the knee, expect some discomfort/pain and back off when that point is reached. Try to go a little farther each time.

As the swelling comes down, flexion and extension will improve. Stick with it as it's worth every second.