I have had knee and back problems since before I started kiting and switched to a kite skim for 90% of my riding. It's easy on the body and
much more fun that a twin tip in light winds. When you start out, you will feel like it's nukin' in 15 knots, and the crashes are pure comedy.
Here's a couple of things you can do to ease the pain on a twintip-
1. working on your jump and landing technique can really help. A crappy takeoff means a crappy landing.
2. I ride really loose straps- it allows a LOT more freedom for your ankles/ knees, seriously improves your ability to go upwind, and gets you ready for boardoff tricks, which (if all goes well) you float down gently whether you pull the trick or not.
3. decide which tricks are worth the pain. I don't do anything crazy in high winds, just boost a few big jumps, lots of carving around, and different transitions.
BTW, Lindsey, I think I saw you doing a backroll on Fox news last night.
www.kiteboardingtampabay.com