KANSAS CITY, Mo. – The Boston Red Sox placed third baseman Kevin Youkilis on the disabled list because of a back injury Thursday and called up catching prospect Ryan Lavarnway from Triple-A Pawtucket.

Youkilis, who is hitting .266 with 17 homers and 78 RBI, missed several games recently because of what Manager Terry Francona called “a back strain or sprain.” Youkilis remained in Boston after Wednesday night’s game against Tampa Bay to be examined by doctors at Massachusetts General Hospital. He also received an injection to alleviate some of the pain in his lower back.

“His body was so beat up anyway, I think this was the last straw, kind of put him over the edge,” Francona said. “But hopefully we can get him back to where he can be Youkilis. I think after the game (Wednesday) it was obvious we needed to get him checked out.”

Youkilis, 32, was selected to his third All-Star game this year. He joins a growing Boston disabled list that includes designated hitter David Ortiz (bursitis in right foot), reliever Bobby Jenks (sore back), and outfielder J.D. Drew (left shoulder impingement).

“You lose one, it’s kind of a big deal, you lose two, it doesn’t help,” Francona said. “But you know, our challenge is to not let it affect us winning games, so that’s what we’ll do.”

Jed Lowrie and Mike Aviles will split time at third base with Youkilis on the DL.

Lavarnway, who started the season with the Portland Sea Dogs, could have the opportunity to catch, though his defense hasn’t progressed as rapidly as his bat. He hit a combined .293 with 30 homers and 85 RBI at Double-A and Triple-A, and that’s why Francona expects him to be primarily the designated hitter while he’s with the team.

“I tried to keep my head out of the roster up here,” said Lavarnway, a sixth-round draft pick in 2008 who has shown considerable power at every level. “I didn’t want to get too ahead of myself.”

Lavarnway said he didn’t expect to make it to the majors so quickly, and hardly worked with the starting pitchers in spring training, when young catchers who might have a chance of making the major league team are usually given a look. He flew into Kansas City on Thursday morning, but still wasn’t entirely sure he was added to the roster until he landed in the afternoon.

“It was bad on the plane. I had knots in my stomach,” he said. “Now that I’m here it’s back to business. The routine will help me get back into it.” 

PHILLIES: Center fielder Shane Victorino’s suspension for his part in an Aug. 5 benches-clearing brawl was reduced and he will miss two games. 

INDIANS: Outfielder Austin Kearns was released. Kearns, 31, hit .200 (30 for 150) with two homers and seven RBI in 52 games. He signed as a free agent with Cleveland in December, his second stint with the Indians. 

RANGERS-PIRATES: Texas acquired right-handed pitcher Tim Wood from Pittsburgh in a waiver deal.