Venice suggestions

Yikes. I'm not sure if Venice will be for you. It was made for walking, plus plenty of steps, bridges, etc. There is the Vaporetto which is the water bus system that can get you from place to place, but still plenty of walking in between. Even your hotel will likely require a walk as you lug your suitcase behind you.

I'm curious now for better answers than mine that may actually be helpful.

Yikes, indeed. Is it too late to change your plans? Seriously, Allan is right. Lots of steps and cobblestones, the bridges have steps, not ramps...

It is possible to use the canal boats to get from one place to another, though, so if your knee will let you walk for short distances you could plot your routes carefully and rely on water taxis. It will still be cumbersome, and could get expensive.

Ahhh..Venice. one of my very favorite places...but that is because there is so much walking EVERYWHERE. Yes..there are boat rides but you must get to them. If it was summer you could place yourself in a neighborhood cafe and just enjoy but that will be difficult in Winter. I would be the last person to tell you not to go..I think alot depends on the neighborhood in which you are staying. Perhaps a conversation with your hotel could assist you. I do hope you get there and just enjoy yourself!

This might help.
https://www.sagetraveling.com/Venice-Disabled-Access

We were just in Venice a few days and the only place we could get to from our hotel without crossing a bridge was the Ca D’oro vaporetto stop. After our first day, I thought I was going to need hip replacement surgery when I get home.

both Murano and Burano (and Torcello) are relatively bridge free on major routes around. Plus the comfort of a somewhat long vaporetto ride through the lagoon.

Where is your hotel or hotel equivalent?

Grazie a tutti!
Aussie, I read and reread the wheelchair guide. It gave me a small bit of hope and then when I woke up this morning my leg was (marginally) better, first time in six days.
So I’m headed to Venice tomorrow. If it turns out to be too much of a problem then can return to Rome.
I’ll also head out to Murano, Burano. I had wanted to do that anyway so thanks for that info. I’m going to give it a try.
The woman at VRBO has helped me out a lot too. She promises ice in the apartment refrigerator.
Fingers crossed! I’ll let you know how it turns out.

Walking poles or a cane can take some pressure off that knee and help.

And go to a pharmacy and get an elastic support for your knee.
Hope you've got some tylenol and some Ibuprofen too, take it before you set out each day, then ice your knee and elevate it when you come back in.