Plouffe, who is on the disabled list retroactive to July 21, was told there is no structural damage to his thumb, which was injured when he was jammed on an inside pitch against the Royals on July 20.
"It was a good report," general manager Terry Ryan said. "They didn't have to inject him. They didn't do a MRI. They just think it's a bone bruise. We'll move on as soon as he's ready, and we'll start the process here, batting practice and all that other stuff."
Ryan said he expects Plouffe to be ready to return once he's eligible on Aug. 5. Danny Valencia has been playing third base in his place.