freeskiing said..
the question was targeting the kind/mode of pressure on one's knees with windsurfing as compared to kiting. as i just have had my 4th knee operation i am thinking of what is going to be in 3-5-10 years.
I had my knee operated on about 35 years ago, removed most of my Medial meniscus, the doc said you'd get back to about 85%. He was right, but that was awhile back, what's left of my meniscus is about all worn off now, I'm now close to
bone to bone. However I'm still out there in the waves windsurfing as long as the wind is blowing, and I have very little problem with it, I just don't jump like I used to. When windsurfing I keep my knees bent and flexible absorbing the sock in the process, you can see what chop is coming so there really aren't any surprises, just pay attention.
Where I do have a problem is with running and my SUPing. Standing there paddling seems to grind both my knees, and spending any time
on my knees is not nice anymore, and there is no unweighting while SUPing like there is with Wsurfing, so I can't SUP for very long. With Wsurfing, your front foot is actually pressing up in the foot strap more than down on the board, and when my bad knee is in the rear I make sure my knee is inline with my foot and ankle so the leg isn't twisted. I can stay out there 2 hours easy riding waves and being in wind from 5.2 to 3.7, no problem. I don't see myself having to give up Wsurfing anytime soon, my bad knee is keeping up with the rest of my body, but I may have to hang up my paddle in the near future, and no more running.
Kiting? I don't go there, and my knee doesn't need another learning curve.
Keep windsurfing, it may actually help by keeping your leg muscles healthy, which a bad knee needs.
I've also been wearing a neoprene knee brace/sleeve (no hardware) under my wetsuit for about 20 years now.