Big John's injury -- any more details?

The article on the front page only mentions that someone demonstrated a darce choke on him.  Did he have a preexisting injury?  Did the student use excessive force?  As a bjj practitioner, it is scary to think something so commonplace could have such a result.  Anybody know anything more about what happened? 

Sounded like a freak thing

He explained it in MMA hour

He was demonstrating how to do a darce and walking the student through who had the grip and angle wrong. He said he was in the position for a few minutes as he walked the student through the motions to correct his positio. Felt fine that day but the next day was in serious pain

He explained it on the mma hour.

Sorry. App didn't show me the reply above me.

You'll need to submit your question, in writing, to BJMs designated PMI Officer and wait for them to get back to you.

as John demonstrated the choke and the student prepared to tap, a burly onlooker barreled in to break them up and injured BJM in the process

Boom Boom Mancino -

as John demonstrated the choke and the student prepared to tap, a burly onlooker barreled in to break them up and injured BJM in the process

Ha

John forgets that at 70 you’re not quite as supple when compared to your youthful pomp. Injuries are inevitable.