Capitals defenseman Mike Green, who has missed 60 of the last 72 regular season games because of injury, becomes a restricted free agent at the end of this year.` (Toni L. Sandys)

Over the next few months, the Washington Capitals will have to answer a tough question about Mike Green’s future: re-sign the No. 1 defenseman in the hopes he can stay healthy, or go in another direction?

When Green is 100 percent, he’s rushing the puck end to end, making precise outlet passes, scoring on the power play and igniting capacity crowds at Verizon Center.

But the two-time Norris Trophy finalist can only have an impact on a game when he’s in it. And over the past two seasons, that’s been all too rare.

On Monday afternoon, the Capitals announced that Green’s latest ailment — a right groin muscle injury — would require surgery, which was performed Tuesday in St. Louis. He’s expected to be sidelined four to six weeks.

Going under the knife was the last resort. But it had become obvious after his setback in San Jose that rehabbing just wasn’t working. By having the tear surgically repaired, the timeline for his recovery becomes more certain.

If all goes according to plan, Green would be on skates in a few weeks. Shooting pucks soon after that. And back in the lineup late next month — just ahead of the Feb. 27 trade deadline.

That means General Manager George McPhee would be afforded just enough time to evaluate Green’s recovery before deciding whether or not the team needs to acquire a defenseman for the stretch run and playoffs. Last season, McPhee traded for Dennis Wideman because of injuries to Green and Tom Poti. A similar move might be necessary this season, too.

But that’s a short-term concern. A much more significant one, with longer lasting implications, looms this summer.

Green needs a new contract. He’s set to become a restricted free agent on July 1 and currently is the team’s fourth highest-paid player behind Alex Ovechkin, Nicklas Backstrom and Alexander Semin with a cap hit of $5.25 million.

To retain his rights, the Capitals must tender a qualifying offer of $5 million, a steep price considering Green has been sidelined for all but 10 of the Capitals’ 43 games this season and 60 of the team’s past 72 regular season games. Green and his camp probably will seek a long-term deal, pointing to his 70-plus point seasons in 2008-09 and 2009-10 and his upside. A stretch of strong play when he returns would help their case.

McPhee could also attempt to trade Green, but that market figures to be tepid, at best, considering the 26-year-old’s checkered medical history.

Any way you look at the situation, it figures to be a difficult choice for McPhee.

On the one hand, there’s no doubting what Green means to this franchise. After all, this is “Game Over Green” we’re talking about here, the “One-Man Breakout,” “Lambogreenie,” a founding member of the Young Guns, a fan favorite whose No. 52 jersey dots the sea of red on F Street. He was here when the team stunk. He was vital in its return to relevance. And, if healthy, he could be a critical component in coming seasons — “if” and “could” being the operative words.

On the other hand, McPhee has spent the better part of 24 months figuring out how to keep his team competitive minus one of its most important pieces.

To review: Green has been sidelined with shoulder, knee, hip flexor, ankle and groin muscle maladies. Along the way, there have also been two concussions, which, according to some around the NHL, are more concerning than all the others combined.

Complicating matters is the team’s recent surge with Green rocking a stylish pinstriped suit rather than a red, white and blue uniform. They’re 9-1 with him on the ice this season. But there’s also growing evidence that the Capitals have learned to cope in his absence. They briefly returned to the top of the Southeast Division standings this week and now sit a mere point behind Florida, a smidge out of third place in the Eastern Conference.

Which brings us back to McPhee’s quandary.

In the end, it’s likely going to come down to whether McPhee and his medical staff believe Green has been the victim of bad luck, or whether the injuries are symptomatic of deeper problems.

If they determine it’s misfortune, then they ought to keep him and cross their fingers and hope he returns to his all-star form. But if they decide the injuries are the result of Green constantly putting himself in vulnerable positions, or that his body simply can’t withstand the rigors of the NHL, it might be time to move on.