My trick knee is throbbing once again.

This time it’s telling me NBC News anchor Brian Williams has some more explaining to do about a made-up story that got him some seriously happy — and falsely premised — publicity over the weekend.

You see, it turns that Williams erred in recounting a story that he had been aboard a Chinook helicopter that had been hit by enemy rocket fire in Iraq in 2003. He had befriended an Army command sergeant major, Tim Terpak, who — according to Williams — had provided cover for the anchorman and other passengers aboard the downed helicopter.

http://www.stripes.com/news/us/nbc-s-brian-williams-recants-iraq-story-after-soldiers-protest-1.327792

Williams and Terpak went to a New York Rangers hockey game the other evening and both of them stood and accepted the crowd’s applause as the public address announcer revealed the story about Terpak’s heroism in protecting the passengers and crew, which allegedly included Williams.

It now turns out Williams wasn’t there.

This is a serious smirch on Williams’s reputation as a veteran TV journalist who trades on the “trust” he has built with the viewers of his nightly newscast.

Williams has recanted the story, apologized and said he “misremembered” the events of that day. He actually had arrived about 60 minutes after the chopper was shot down.

Misremembered? For a dozen years?

The anchorman came clean only after other soldiers who were there protested, telling others they had no memory of Williams being present when Terpak — who’s since retired from the Army — engineered the getaway of those aboard the Chinook.

“I would not have chosen to make this mistake,” Williams said. “I don’t know what screwed up in my mind that caused me to conflate one aircraft with another.”

Neither does anyone else.