Sorry, Mbone.....I just now am catching up with your thread. You've been through quite a lot in the past couple of years! But I think you're doing just fine.
Knees can be a bit harder to recover from than hips, so it's not surprising that your new knee is hurting a bit with this latest surgery. It's having to pick up a lot of slack from your left side that's in recovery mode. Be sure that you're not trying to push yourself too hard with activity or exercise at this early stage. Also, be sure you allow yourself plenty of time in transitioning from walker to crutches to cane to nothing. Your knee will appreciate the extra support a walker provides in these early weeks and you shouldn't transition to any new walking aid until you master the current one with a good long stride and no limping. Remember.....this is all only temporary.
Your knee is strong and you won't hurt the implant. But you can make some of the soft tissue angry and that may give you some swelling. You won't lose ROM as long as you're up and walking about a couple of times a day, although if the swelling gets going, you may temporarily regress a little with the knee. It's best not to let that happen. If you need to ice and elevate your knee at the same time you're doing your new hip, that's just fine!!!