sorry to hear this.
Forget about wakestyle, since this style has very hard landings (keep the kite low for more power...).
At at 29 you are already "old".
Don't make the mistake to follow the "trend" of wakestyle and f*** up your knees for lifetime...not worth it!
You see all the kids busting their knees, and they are young! e.g. Youri Zoon. He has many problems with his knees, but he is trying to be back strong. And always has problems again, because I also think he doesn't give himself enough rest to cure it completely.
Waveriding can be a problem for your knee, e.g. if I want to hit a wave and do a big spray, I have lots of power on my leg and knee, so it has to hold a lot. But if you do more the surfing style and surf it, it shouldn't be any problem. Just look out, when you want to go over a wave and it breaks right in front of you, that you get out of teh straps quickly and don't hit the wave with your feet in the straps and your legs stretched...search for "Neil Hutchinson knee" and you will see what I mean...
In general, if you feel you miss a landing and will hit hard, get rid of the board, so your legs/knees stay out of trouble.
I had a small problem with my knees as well. Played tennis, and knee became always thick, and couldn't really walk. Kiting caused less problems. Took it easy with my knee, played less tennis, and then with a knee support (bandage). Funny thing is, now I don't feel anything on the water, kiting quiet a lot with lots of pressure on my legs. Good, that I didn't do any surgery on my knee. Always better to not do anything, if possible.
Good luck for all!