MINNEAPOLIS -- The Twins agreed to terms with right-hander P.J. Walters on a Minor League deal with an invitation to Major League Spring Training, the club announced Monday.

Walters, who was outrighted off the 40-man roster on Oct. 24, made 12 starts with the Twins in 2012, posting a 5.69 ERA with 42 strikeouts and 22 walks in 61 2/3 innings. He was signed before the season as a Minor League free agent.

The 27-year-old has a career 6.39 ERA over parts of four seasons with the Cardinals, Blue Jays and Twins. He has struck out 82 and walked 44 in 112 2/3 innings.

Walters figures to compete to be a starter next season, as left-hander Scott Diamond is the only pitcher who is guaranteed a spot in the rotation.

Blackburn has bone chips removed from elbow

MINNEAPOLIS -- Right-hander Nick Blackburn had bone chips removed from his right elbow late last week but is expected to be ready in time for Spring Training, the Twins announced Monday.

Blackburn, 30, struggled in 2012, posting a 7.39 ERA in 19 starts. The sinkerballer also struck out 42 and walked 26 in 98 2/3 innings.

He was eventually outrighted off the 40-man roster on Aug. 20 and sent to Triple-A Rochester, where he finished the season.

Blackburn is owed $5.5 million next season in the final year of a four-year, $14 million deal signed before the 2010 season. The Twins also hold an $8 million option for 2014.

Blackburn has a career 4.85 ERA in 818 2/3 innings over six years with the Twins. He's struggled over the last three years, logging a 5.56 ERA after posting a combined 4.04 ERA over the previous two seasons.