My personal take on this is that pre-surgery there's not much to do. Exercise probably hurts too much anyway. Key is recovery; gently maintain mobility with stretches until healing is pretty much done, then resume strength/fitness work.
@FourCats, my surgeon had me take 6 weeks of PT before my Bilateral TKR, and they were the exercises you mentioned. @Lilmarbeth, one of the most important things you can work on is UPPER BODY Strength. You need it to get out of bed, the car, standing up from the toilet, chair, etc. I was surprised that my physical therapist never had me do upper body exercises. Luckily, I have always had that strength, but it’s as important to recovery as the lower body. Just my two cents worth. Good luck, this is the place to seek answers. I would have been totally lost and miserable without BoneSmart.
@Lilmarbeth My pain greatly decreased when I started doing pre-op exercises, but you may not have the same result. My routine included glute squeezes, clam shells, straight leg lifts, short quad archs, heel slides, thigh squeezes, mini squats, side straight leg lifts, and toe raises. It didn’t take very long, and I didn’t do them all at once. If you do a browser search for “pre-op TKR exercises,” you will see a number of results with illustrations. There also are a lot of videos on You Tube on the topic. From what I have read, you want to go into surgery with strong quads and as much extension/flexion as possible. Best wishes for a smooth recovery.