Bear in mind I only very recently started watching combat sports, so I'm still unfamiliar with many techniques and the history of the various sports. Explain it like I'm 5 if you must.

In Judo and BJJ, there are specific techniques that are banned in tournaments, sometimes depending on skill level, due to the risk of crippling injuries. Two examples are jumping to closed guard and a scissor takedown (kani basami). Add your victim's unfortunate footwork to your body weight and momentum of these techniques, and you might accidentally inflict gruesome leg injuries (there ARE videos of this, if you're curious). Awareness and adjusting footwork seems to be the main way to avoid those injuries.

My intuition is that the striking aspect of MMA keeps fighters at a distance where these moves are less practical to attempt, but closing that distance to clinch and grapple happens quite often. So why weren't these techniques attempted more and cause accidents in MMA as they had in Judo/BJJ?

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    There is a trade-of of realism vs risk of injury. In MMA, the trade favors realism more then in Judo or BJJ. Commented Jul 28, 2020 at 10:41
  • I do see that, but when I say "why hasn't it become an issue" I mean why haven't we seen more people landing badly (or purposefully) on legs and breaking them. These moves aren't even attempted that often.
    – BatWannaBe
    Commented Jul 29, 2020 at 5:46
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    Professional MMA is not only fighting, but also a business. Purposefully and badly injuring opponents in front of millions of viewers probably does not have a good impact on the share value, both of the company as a whole and the fighters individually, not to speak about the standing of such a fighter within the community of fellow fighters. Commented Jul 29, 2020 at 7:31
  • Fair point that addresses why people aren't intentionally snapping legs, Anderson Silva's leg breaking on a checked kick was not well-received, to put it lightly. He did lose to a rare scissor takedown by Ryo Chonan, no legs broken.
    – BatWannaBe
    Commented Jul 29, 2020 at 8:36

2 Answers 2


Usefulness of "dangerous" moves

why haven't we seen more people landing badly (or purposefully) on legs and breaking them?

Because it's actually really hard to cause damage with these moves, and a lot of that is just luck. They're banned because a small but significant percentage of attempts will, due to a the opponent's split-section reaction but also chance, cause serious injury. But it's not like they're "overpowered" moves in a videogame. The majority of scissor takedowns result in no injury. Checking a kick results in a broken leg maybe one time out of a thousand.

Another aspect is that both of your examples, the scissor takedown and jumping guard (which is, I note, only banned at white belt), have major drawbacks in MMA. The scissor takedown is quite hard to set up from striking range, and if it fails you've pulled a bad guard. Both pulling and jumping guard put you underneath someone who would love to hold you down and hit you until the end of the round while you squirm to get back to your feet – tactically, it is a choice riddled with problems. Jumping guard is worse, because it gives your opponent the opportunity to slam you. Few MMA fighters want to take the risk to themselves that these techniques present.

Different risk/reward profiles

Any sport that involves getting punched full force in the face is, by nature, going to attract people more willing to be injured. Grappling sports are intended to be easier to take part in without serious or permanent injury. Therefore more techniques are banned in grappling.

Striking sports like boxing, kickboxing, and MMA involve more infrequent competition and much more acceptance of risk than grappling. (This is somewhat less true in a Thai context, and lower-contact striking sports like tae kwon do are somewhat of an exception, but overall this is overwhelmingly true in the West.) The sport is designed for participants who want to trade safety for freedom and realism.

Expected competition participation

Judo rules are intended to be universal, used almost identically from community tournaments all the way through to the Olympics. The only difference between a white belt adult competing in my region and the world championships was that armbars weren't allowed until sankyu. Global consistency is highly valued.

Another core value of judo is safety for the massive volume of participants. Judo is almost as popular across the world as soccer, and it's expected that judoka will compete often and at all ages. The rules have to take this into consideration. Therefore jointlocks are limited to the absolute safest--those attacking the elbow, which come on the slowest and do the least long-term damage--to minimize the number of life-altering injuries caused by the sport. Similarly, many throws like kawazu gake which endanger joints are banned, because the large number of worldwide judo competitors would cause a large number of risky throws to be attempted, and thus a non-negligible number of long-term crippling injuries. Allowing the technique would make judo much more of a niche sport.

At a guess, MMA has 1/1000th the number of participating competitors per year, maybe fewer. The number of people put at risk is almost not comparable.

  • Your detailed answer really helped, thanks! Out of curiosity, I looked up kawazu gake, and it doesn't LOOK that risky. Just kinda looks like you hook a leg and do a throw like any other. How does it endanger joints? Is there a telltale sign of techniques that endanger joints?
    – BatWannaBe
    Commented Jul 30, 2020 at 2:14
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    @BatWannaBe Fully grapevining around someone's knee and then dropping your weight are individual risk factors that also synergize. This throw is unusually risky because it a high chance of putting serious lateral pressure on the knee, especially as someone resists. It also makes moving safely difficult, because as you're thrown your knee is trapped in some position that may not be safe, and now your opponent might land their hips on that leg, too. Commented Jul 30, 2020 at 7:53
  • That makes sense, when you add resistance, things don't go as quickly and cleanly as they do in the rehearsed demos. I wonder if judoka ever feel some anxiety about a big sacrifice throw, not knowing if everything lands where it's supposed to.
    – BatWannaBe
    Commented Jul 30, 2020 at 8:50
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    @BatWannaBe My club had a rule that higher belts were not allowed to try sacrifice throws on white belts, because the breakfalls are often more difficult or involve knowing not to try to breakfall in a particular direction (or else you faceplant or risk a shoulder). Commented Jul 30, 2020 at 8:57
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    This is a common rule in the vast majority of Judo schools. Do NOT attempt Sutemi Waza on people below orange belt. It can end very very badly.. And even in Sutemi Waza, there are techniques that should not be attempted with an unskilled opponent EVER. Mainly the throw mentioned by OP, Kani Basami. As well as Maki Komi. If you don't know how to break your fall, Maki Komi's going to make you feel really really bad if you land hard.
    – Sjana
    Commented Sep 22, 2020 at 16:00

MMA has less restrictions on what's acceptable, as it is a combative sport where fighting is the purpose. Conventional martial arts sparring is a demonstration of skill and discipline. Never the less, certain....rules do apply even in MMA. Martial arts, lethal finishing moves are taught, But not encouraged. MMA rules prohibit.. Groin attacks, kneeing the head on a grounded opponent, strikes to the back of the head or the spine, head butts. (Sorry, soccer fans.), eye gouging, fish hooking (Mouth/lip grabbing), No fingers in an opponent’s orifices. (Eww!), biting (Sorry Holyfield), hair pulling (though many shave/cut their hair), striking or grabbing of the throat. REAL self defensive or militant martial arts teach these techniques.

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    This does not answer the question why techniques forbidden in other martial arts because of risk of injury, for example leg scissors in Judo, do not seem to cause injuries in MMA although they are allowed. Commented Nov 7, 2020 at 7:17

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