The Baltimore Orioles have placed right-hander Jason Hammel on the 15-day disabled list with a right knee injury, reports Steve Melewski of MASNsports.com.

O's make move official. Hammel to 15-day DL and Steve Johnson recalled from AAA.

— Steve Melewski (@masnSteve) July 15, 2012

To replace Hammel on their roster, the Orioles have recalled right-hander Steve Johnson from Triple-A.

Hammel sustained his injury during the fourth inning of Friday’s start against the Detroit Tigers. The 29-year-old announced yesterday that he will undergo surgery on his right knee in order to alleviate the discomfort that forced him out of Friday’s game.

Hammel had been Baltimore’s best starter this season. Acquired by the Orioles in the trade that sent Jeremy Guthrie to the Rockies, Hammel has maintained an ERA and WHIP of 3.54 and 1.244 with 8.7 SO/9 and 3.2 BB/9 over his 109 1/3 innings.

Right-hander Tommy Hunter is expected to be recalled to make Hammel’s next start. Hammel’s injury could have the Orioles, who were already said to be in the market for an established starter, even more interested in making a move prior to the trade deadline.

Steve Johnson is a Baltimore native and the son of former Orioles pitcher Dave Johnson. He made his major league debut yesterday, allowing one run on one hit with a walk and two strikeouts over his two innings of work.

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Do the Orioles need to add a starter this summer?

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