I have heard of so many people falling after TKR, makes me want to buy knee pads. Wonder if it's due to an altered gait, weaker quads or just life.
In my case it could be because I had both knees replaced, but I've had this discussion with quite a few members. The first months to a year or so after my TKR, I noticed my balance was... off. Not bad. I was perfectly stable on my new knees, but some things just threw me off.
At first, the first months, I found myself shuffling sometimes, falling back into the old knee-sparing, limp-balancing habit of how I walked before surgery. One reason that happened was because I WAS afraid of falling. So I walked protectively. I worked on getting rid of that "protective" gait and that got normal.
I also noticed that if I looked around when I walked, I would wobble if I looked to the side (or anything not straight ahead) for very long, and especially if I looked back over my shoulder. Wobble. A wobble can easily turn into a fall. I worried about if I would always be wobbly, but... you got it, I worked on that. I made a point of looking to the side on occasion, or behind me, just to train my brain to be used to it.
Falls are never good. Most of us are older and have knee replacements, and that's a caution-inducing combo. But I've found that as I continue past recovery -- I'm twenty months post-op now -- I've gotten better and better on these new knees. Yes, the muscles get stronger again. The brain relearns balance and adjusts to a new, better gait. I bike. I walk on snow and even ice without fear of falling (got my good Wisconsin winter legs back!) and now only fear wet floors. I fell once (pre-bad knees) on a wet floor. There will always be fear of wet floors.