Kevin Klein’s back injury was supposed to be a quick thing, but just like the other back injuries the Rangers — and the rest of the world — have dealt with, it rarely is easy.

The defenseman missed a sixth straight game Saturday night, a 4-1 Garden loss to the Canadiens, with what is being called “back spasms.” Coach Alain Vigneault said Klein had an MRI exam this past week, “to make sure we weren’t missing anything,” but it showed “nothing.”

Klein first tweaked his back during pregame warmups on Feb. 23 in Toronto. That extended period on the shelf likely is going to prevent Klein from at least starting the upcoming four-game road trip, which begins Monday night at Tampa Bay.

“Usually it doesn’t take this long,” Vigneault said, “but it is.”

Henrik Lundqvist made his 735th career appearance, passing the Red Wings’ Terry Sawchuk for the third-most appearances with one franchise in NHL history, behind just Martin Brodeur (1,259 with the Devils) and Tony Esposito (873 with the Blackhawks).

His next win will be career victory No. 404, and he will pass Brodeur’s record for the most wins by a goalie in his first 12 seasons in the NHL. He will also pass Grant Fuhr for sole possession of 10th place on the NHL’s all-time wins list.

Speedy winger Michael Grabner, the Rangers’ leading scorer, also was out, missing a second straight game with a hip injury. Vigneault called Grabner “day-to-day,” and he likely will be on the trip.

Defenseman Dan Girardi remained out for a third straight game. His right-ankle injury is expected to sideline him at least another 10 days.

Winger Jesper Fast missed his second straight game with a shoulder injury, suffered on Tuesday. It is supposed to keep him out 2-3 weeks.

The Rangers’ power play didn’t get a single chance, but the team came in riding a season-worst streak of futility, having gone 0-for-19 over the previous seven games, 1-for-33 over the previous 12 and 3-for-52 over the previous 19, dating to Jan. 19.

“It seems like power play, they go in spurts,” Vigneault said. “Right now, it’s no doubt that our guys are thinking about it a lot. It’s brought up a lot, so it’s in the back of your mind. You sort of have to shut the mind off a little bit and execute and make some plays. Probably simple is better.”

As for possibly changing his personnel, Vigneault joked: “Contemplating all the time, baby!”