Lol. Way too many rustled Jimmies in this thread. The oblique kick is about as dangerous as stepping off a flight of stairs one step too early. Leg submissions and regular leg kicks--both outside and inside--cause much more damage than oblique, side, or front kicks to legs. The primary objective of such a kick isn't "destroy this dude's ligaments;" it's to keep distance, vary your techniques to remain unpredictable, and frustrate your opponent.
You guys are acting like fighters' careers are ending left and right due to it or something. I may be wrong but I'm pretty sure there have been no significant injuries in the UFC or any other major organization from those kind of kicks. Brandon Vera landed a devastating oblique kick to Jardine that clearly hyper-extended his leg and he still ate it like a cupcake and remained unscathed. Me and my buddy would throw all sorts of those techiques at each other's legs during dozens of sparring sessions last summer and neither of us came close to feeling like we were at great risk of injury.
Unless you're the Tin Man from Wizard of Oz you have nothing to worry about. The Polar Bear needs to chill. He talks about this dirty technique then proceeds to discuss how he'd brutally murder someone in a street fight like he's Baraka from Mortal Kombat.