Anthony Castonzo out with knee sprain

• Bucs at Colts, 1 p.m. Sunday, Fox

Just when you thought it was safe to exhale about the Indianapolis Colts’ offensive line, here comes this: Anthony Castonzo, the unit’s stalwart left tackle and most reliable member, goes down.

Coach Chuck Pagano confirmed Monday that Castonzo is dealing with a sprained medial collateral ligament in his right knee, an injury that could sideline him for multiple games based on Pagano’s week-to-week description.

Castonzo suffered the injury on the Colts’ final possession of their 24-21 victory Sunday against the Atlanta Falcons.

The Colts now are dealing with another key injury in a season when it seems such injuries are a weekly occurrence.

“You hate to lose anybody, especially your starting starting left tackle,” Pagano said. “Quarterback one week, now the left tackle. This guy, that guy. Mike Adams, the quarterback of the defense (Adams missed Sunday’s game).”

Watching Castonzo go down is particularly tough, Pagano said.

“I hate it,” he said. “Sick for him. Because he don’t miss. I think he missed a couple games his rookie year. He is the rock.”

Thumbs up/down: Joe Reitz, running back?

Castonzo has started 66 consecutive regular-season games dating to his rookie season in 2011.

His injury is just the latest of note for the Colts. This season, the team has lost starters Arthur Jones (season-ending ankle surgery), Andrew Luck (has missed three games with more to come), Greg Toler (missed four games with a neck injury), Henry Anderson (season-ending knee surgery) and Adams (has missed two games).

Now, the cornerstone of the offensive line goes down, leaving the unit in a state of flux.

“They’re not canceling the game on Sunday,” Pagano said. “So, we’ll find a way.”

The Colts host the Tampa Bay Buccaneers on Sunday at Lucas Oil Stadium. Their offensive line configuration is yet to be determined, but the Colts could be forced to do extensive shuffling. After Castonzo left Sunday’s game, the Colts moved Joe Reitz from right tackle to left tackle, Jack Mewhort from left guard to right tackle, and inserted Lance Louis off the bench at left guard.

To say there are no great options would be an understatement. Mewhort, remember, began the season at right tackle and had a rocky start. The Colts, after spending the entirety of their offseason working with a specific lineup, upended three spots on the line after dreadful play in the season’s first two games. That’s when they moved Mewhort back to left guard and benched guards Louis and Todd Herremans. Joe Reitz, meanwhile, took over at right tackle, with Hugh Thornton going to right guard.

In subsequent weeks, after the beating Luck took in those first two games, the line has stabilized. It’s unclear whether those early hits contributed to the shoulder injury that sidelined Luck for two games back in October, but they certainly didn’t help.

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The big wild card for the Colts is Mewhort moving to tackle. He’s a solid interior lineman, but playing tackle — based on his early-season performance — is not a strength. Beyond that, the Colts have to find a workable solution at guard if they do move Mewhort to the perimeter. Given the past performance of Herremans and Louis, neither seems like an ideal solution.

One move that seems likely is Reitz sliding to left tackle. He’s been something of a Swiss Army Knife for the Colts, beginning the season as a swing backup at tackle and guard, then starting at right tackle and now, presumably, heading to the all-important left tackle spot.

“He’s played really well,” Pagano said. “… He’s smart. He’s tough. He loves playing. He plays with a ton of energy and passion. He’s got position flexibility. He’s our emergency, emergency, emergency center if it ever got to an Armageddon scenario.”

As Pagano brought his Monday news conference to a close, he turned to humor, perhaps in a necessary effort to lighten the mood after the unfortunate news about Castonzo. So, he turned to Reitz’s “rushing attempt” on Sunday, one on which he took a pitch from quarterback Matt Hasselbeck and slid forward for a gain of zero yards – one yard short of a first down.

“He’s not much of a runner,” Pagano cracked. “We’ll throw that play out. We won’t be running that one again. One special teams play (last month’s infamous fake punt), we’ve thrown out, and the Joe Reitz play is gone for good. A couple plays are buried out back in the swamp.”

The line drew chuckles from reporters in the room. But unfortunately for the Colts, the loss of Castonzo is hardly a laughing matter.

Bucs at Colts, 1 p.m. Sunday, Fox