I have two knee replacements and do yoga twice a week. What works for me is to tell the yoga instructor before class my need to modify poses. I have done Zoom classes and in person classes. Hopefully, they give a choice of a pose or a modified pose. That has worked for me. Balance is a big issue for me. Presently, for tree pose, I just put my foot against my leg. I don’t even lift it off the ground. Good Luck.