It's not easy to land, but any thrust kick can dislocate/fracture or break a knee, especially a thrust kick that can be modified into a full body-weight stomp. The thing that makes it difficult is the protective rotation of the knee when someone feels pressure on it. The knee needs to be locked before any snapping or breaking will occur. If your kick locks the knee back then yes it can easily be broken with very little effort and if his knee doesn’t lock back then yes you are not going to snap/break anything but you can still tear ligaments and possible dislocate the knee by forcing the knee cap to extend pass its natural range of motion causing stress damage to muscle, ligaments, and bone. People aren’t out to destroy and kill other fighters there out to win. Most UFC fighters will give there opponents options to tap out before the break a joint, not all but most of them will, consider it a professional curtsey "do unto others". And those type of kicks are now Illegal in the UFC so what does that tell you about there effectiveness.
...and how many times have you done that? Before you talk about how easy something is, you should probably try it a few times. I don't know of a single person who stands with their legs completely straight, let alone fights like that.
No I don't break the knees of people just for practice, But I do wrap up Wooden dowels with towels and practice different strikes and stomp/thrust kicks meant to break bones, because that’s just the closest thing to a bone being wrapped up in muscle and tissue that I have found. And their legs do not need to be straight from their stance your kick is what straightens their leg and locks their kneecap. You want to come down on the leg with a 45-degree angle from their knee to the floor, and you need to follow through all the way to the ground. This is basic human physiology and physics.
First of all, the knee is a joint, not a bone. What you're trying to simulate would be breaking the opponent's tibia or femur. But you've never done it, so it's still a theory.
I don't think the debat is about whether it could break someones knee, but whether the technique is going to work in a stressed situation. I think your more likely to miss or slide off than hit, and if you need to follow through to the floor you will definately be entering punching range while presumably looking down at their knee.
Your right about my poor choice in calling the knee a bone, but the tip of the tibia will fracture under stress. And thrust kicks work its been proven, that would make it a principle not a theory.
Where is your proof that it is 'easy' to break someone's knee with a thrust kick during a fight? If you agree that it's likely that you won't break their leg, why do you think breaking their leg would be easy?
Nobody said it is easy, there are various assumptions over many posts here. It will break the knee if executed properly - that part is certain. What is "proper" execution of this particular technique is not the subject of this thread. If you doubt it that much you can find someone that has trained it, sign a waiver, and have them try it on you. Hey, i have never broken someone's joints with an armbar, or had mine broken, therefore i have proof that armbars can't break joints, right?. Same goes for wristlocks and finger manipulation - they hurt but will never ever break anything. I have never knocked anyone out with a hook and i have in fact been hit with a nice right hook without being knocked out. Proven beyond all doubt: hooks can't knock you out. Right? When someone says in a post that "this or that might/is likely to/will probably happen" it means that there is also a chance of "this" or "that" to not happen. This is the reason that the poster does not say "this will most definately happen in all cases no matter what" instead. It is a bit immature, imho, to come up with comments like "this is too hard", "this has never happened", "i have never seen this with my own eyes so it is probably wrong" etc. I will not be posting again in this thread, i have messed it up enough already, but feel free to pm me.
I think common sence needs to come in. This kick whilst yes possible it could take the knee out and do real damage to an attackers leg. But when compaired to a Thai kick it is much easier to land and has a greater chance of inflicting some solid damage. If I try a trapping kick like this and get it wrong then it might do no damage (still hit) but due to alignment of leg etc might not do much so its somantic. If I connect with any part of a Thai kick common denominators will show a large blunt force trauma to the thight, calf, knee or general bone structure so hence damage is done. Better avarage bang for your buck - do we agree all?
Did you read his post? He said: You're logic is seriously flawed. You wouldn't have proof that arm bars don't break arms, what you would have is a LACK of proof that arm bars break arms. That proof can easily be supplied (I'm sure you can find a clip of Mir breaking Silvia's arm). Just to clarify, I didn't say you could never break someone's leg with that kick, I said it wouldn't be easy.