The Athletics called up infielder Donnie Murphy from Triple-A to replace Bradley, who is batting .275 with two home runs and six RBIs. The move is retroactive to May 15.
A's manager Bob Geren said he expected Bradley to be activated when he's eligible to return. Bradley is the 10th player currently on the disabled list for the A's. Reliever Justin Duchscherer went on the DL on Tuesday. Oakland has used the disabled list 12 times already, three fewer times than they did in all of 2006.
Bradley was on the disabled list from April 23 through May 10 with the same injury.
"He's really aiming to come off as soon as possible," Geren said. "He worked real hard today. I just want Milton to get 100 percent healthy, because I know how much he'll help us."
Murphy hit .354 with two home runs and 11 RBIs in 25 games at Triple-A. He played 39 games for Kansas City in 2004-05.