Does anyone have lower back pain after TKR?

YES! I've read it is actually pretty common. I only hurt my back one time in all my 69 years before my TKR, and I really struggled with it afterward. I'm 15 months out and still working on it, but I feel like I've finally figured it out. Mine began with hurting my back by twisting to get up from a sofa, and got exacerbated from there. Now I am doing two things that help a lot -- I use exaggerated marching steps and arm swings around the house, and I stretch my lower back with an extra little wiggle when I use the "recumbent" stationary bike I home. The bike actually sits up like a chair rather than reclining at all, and my arms are straight down at my sides. I have to remember to swing my arms when I walk or I start to feel tension in my back. Doing these things in the past couple of weeks has helped my walking AND standing still.