The Orioles placed Wolfram on the 15-day injured list Tuesday, retroactive to Saturday, with a lower-back strain.
Wolfram hasn't pitched since he gave up one run in two-thirds of an inning against the Marlins last Wednesday, and it appears his absence has been due to a back injury. His move to the injured list will rule him out until at least May 24, and the O's will recall Tyler Wells from Triple-A Norfolk to fill the vacancy in their bullpen.