For that reason the 23-year-old British & Irish Lion was omitted from coach Mike Ruddock's 30-man squad on Tuesday, along with Ryan Jones, Brent Cockbain, Tom Shanklin, Kevin Morgan, Chris Horsman and Luke Charteris (all injured) and Sonny Parker, who announced his retirement from international rugby on Monday.
But Ruddock hinted Henson will be right back in the Wales fold once he is cleared to play again.
He will have one match - Ospreys v Borders on February 17 - to prove his fitness, but will then be available for the clash with Ireland on February 26. Â
"We're optimistic Gavin can come in. He is a class player, there is no doubt about that," confirmed Ruddock.
"I would be confident his skills and level of fitness would be up to scratch.
"We are talking about a player who has played in a Wales Grand Slam team and is a British Lion, so the reality is that a player of that quality and pedigree who can prove his fitness has got to be thought about."
It was Henson who kicked the vital penalty which beat England at Cardiff last year.
But despite his absence at Twickenham in the championship opener on February 4, Ruddock is confident Wales can do well.
"Our record is not very good there (Twickenham). That's pretty obvious when you look through the history," admitted Ruddock.
"But we beat them last year. We did our homework properly. We stopped their driving game. We worked to hold their scrum and got some parity up front, and we managed to get the result.
"So I guess the themes will be the same again but we will also need to do a bit out of the ordinary to score tries to beat them. Hopefully we can get that width on our game again.
"Everyone wrote us off last year as no-hopers, but we got our mindset right and we won the title, so we will be working hard on getting that mindset right.
"The mindset you adopt is crucial. If we go around saying it is twice as hard to defend a title as it is winning it in the first place, then we are never going to get there.
"But if we say 'let's be excited about our rugby as we were last year; let's go out and play the same high tempo game we did last year', then there is no reason why we cannot do well."