I'm 63, 65 lbs. over weight, and have two total knee replacements this year. One in January and one in April. I did the Camino Portuguese in September with no problems. I've done the second half of the Norte and I don't think that would be much of a problem either after your surgery. My Norte was pre OP and it is the reason that I got my knees replaced. It about killed me but I would have no hesitation to do it now.
Two things for you to think about.
1. You will lose a lot of muscle in your post OP recovery because you will be sedentary. Building this back will be key to a successful recovery and any future Caminos.
2. The moment your surgery is over you will be in a race with scar tissue that will want to form around your wound. You'll learn more about this from your doctor and physical therapist who you may not even know yet but the biggest favor you can do for yourself will be to diligently do your assigned knee exercises despite the pain. Those excercises are what wins the race against a knee full of motion restricting scar tissue and will allow you to enjoy your next Camino. I don't think about my knees very much now although I am still careful about where I step.
My last Camino was 5 months post op and both knees functioned well. The Camino was very helpful in building back the muscle that I had lost. Good luck, you can do it. Buen Camino.