This is a defense for a knife in your back & a forearm choke with your back straight. This is a more difficult situation than having your back arched as you don't have any "wiggle room." Be sure to check my footwork as you learn this technique. Footwork is always critical.

Thanks to Sean Gallimore for being my uke and Marc Kolodziejczyk for the photography.

Attacker has a knife in my back & has a secure rear forearm choke.

This is a very difficult attack to defend against. Please be aware that there is a reasonable chance that you might get cut in the process of defending yourself from this attack.

Slightly swing your hips to your right & immediately strike back against his left forearm at the same time. Both actions will cause the knife  to flatten between your back & his front. This will only save you temporarily.

Attacker's natural reaction is to probably pull his knife hand [& knife] out & away from you so he can stab you. Don't forget to look at where my feet are going.

As he brings his knife attack in to you, block it with your left. forearm.

Grab his wrist from behind with your right hand as shown to stabilize location of his knife hand.

Deflect his arm upward as you drop down slightly, stepping out with your left foot. Grab his wrist from behind with your right hand as shown.

Pivot under the attacker's arm as you shift more to your left. Turn his hand/wrist slightly clockwise [so his palm is up] to create sufficient pain/distraction to slip out of the headlock & bring attacker up onto his toes.

Once you've pivoted under his arm you will have a wristlock. Pull it out & down slightly to set and bring attacker further off balance.

Apply forward & downward pressure against the back of his wrist to get him to bend forward. Notice that's I've stepped back with my right foot.

Note closeup of grip on his left hand from the other side. It is important to have your index finger straight, pointing downward, to direct your "ki" properly.

Continue to apply pressure to the back his his hand as you drop down onto your right knee, bringing your attacker down.

Your left hand grabs attacker's left shoulder.

Pull his shoulder around to your left as you start to bring his right arm up into a simple armlock.

Close-up view from the top. Note that I keep his wrist bent & that I'm maintaining my original grip on his wrist/hand.

Once attacker's shoulder is on the ground you can execute a wrist-press submission to get attacker to release the knife if he's still holding it. Be aware that if you press down quickly on his wrist, in this position, you bill probably fracture it.