in karate i'm not sure but i don't think you have knees and elbows included and that's the reason i prefer muay thai over karate...or taekwondo, they're limited to legs only and punches to body (WTF version)
.. not to mention that any of these sports don't even include proper clinching...
for the end, if i offended anyone with my post i appologize for it,
There actually are several different varieties of knees in Shotokan, I'm not certain about other forms of karate. Because Shotokan is a rather aggressive-evasive form of karate it includes a huge amount of step-fighting(not in the context of step-sparring) in that you step in to close distance with your opponent. Many kata's as well as several counter techniques include the use of knees when close to the opponent. As for the "WTF version" it bothers me that people still train only body shots, as well as competitions only allow bodyshot(for the most part). Its not logical, if the art teaches you to strike at the opponent's vital areas, you should be allowed to in competition(except the junkular region, and fatal areas)
In the Kanku-dai kata there is the perfect example of a very similar to Muay Thai clinch. During this clinch you go for the clinch, wrapping your hands around your opponent's neck and pulling him down, then you throw a knee to the face, followed by(in exact Shotokan form) drop low and rotate around to engage another opponent. However in my modified version, instead of dropping and spinning. I attempted to alter it to become a double-leg takedown. I have not tested this on a live opponent yet, since I am not exceedly adept at the motion.
No worries man. You may like Mauy Thai, and that's good for you, but you didn't say the words that really piss off pretty much every traditionalist! So we're good.