Speaking of MMA and nikkyo...
Here is a very NASTY form. Aoki demonstrates an applied version (oyo) of a nikkyo variation (henka). It looks like waki gatami or a "rokkyo" type technique, but if you train it, with firm pressure, the pain is definitely felt in the wrist. I believe he calls it "waki otoshi." With good ukemi, and a mean nage, only the wrist would be broken. Otherwise, uke's tension will allow the power of the lock to transfer into the forearm bones and the elbow.
The nikkyo variation I'm referring to is the one where uke's hand position is a palm placed on nage's chest, almost like a shove. The hand is held in place, and without folding the wrist over, nikkyo is applied. If you have a copy of Takemusu Aikido by Morihiro Saito Sensei, refer to pages 166-167 for "Munadori Nikyo Henka 4."
Here, Aoki demonstrates the variation from a MMA tie up, to get the upper hand in a underhook/overhook scenario. Notice that the person wearing the gloves ENHANCES the technique. Ordinarily, such a glove would make nikkyo harder to do, but in this case, it makes the technique viable since the glove prevents escape.
Here, Aoki wins a match in a brutal manner. Under duress, he applies the technique demonstrated above, with a violent twist of the whole body, while, running out to the center of the mat. On some of the MMA forums, most had no idea what he was doing here. It looks like a elbow lock variation. This is a d*ck move, I think, even in competition. His goal was to clearly go for the injury before the submission. The guy NEVER had a chance to tap. Look for yourself and see just when the guy realized his was beaten. Also, look where the injury occurs. Really nasty but effective.