They placed him on the 15-day disabled list Wednesday with inflammation in his right elbow. Worley had an ultrasound Monday and an MRI on Wednesday, which revealed inflammation in the posterior joint.
"No structural damage," Phillies general manager Ruben Amaro Jr. said.
The Phillies plan to keep Worley, who has had discomfort in the elbow for about a month, from throwing for one week. He will be re-evaluated at that point. If the elbow has improved, he can begin his throwing program.
"Generally, it's pretty good news," Amaro said. "When you don't have structural damage -- as far as the future is concerned -- that's a good thing."
Amaro and Phillies head athletic trainer Scott Sheridan said Worley's elbow injury is different than other elbow injuries Phillies pitchers have suffered in recent seasons, like Joe Blanton, Jose Contreras and J.A. Happ. Each of those pitchers stopped throwing for a period of time and started throwing again only to suffer a setback.
"This is a different one," Amaro said. "This is some inflammation in the joint, and we think it's more mild. But we won't know again until he's throwing again, how he feels and how long it will take. Just because it's the elbow ... there are a lot of different things that can go on in the elbow. This is different from some of those."
Right-hander Kyle Kendrick will pitch in Worley's spot in the rotation while he is out. Left-hander Joe Savery took his spot on the roster.
"Hopefully it's only two or three [starts], and we'll go on from there," Amaro said.
The Phillies have little starting pitching depth after Kendrick, so an interesting name resurfaced Wednesday.
Could the Phillies bring him back, much like they brought back Pedro Martinez midseason in 2009?
"We think he's throwing," Amaro said of Oswalt. "I guess he is. But right now, what I'm worried about is our team playing better. That's my focus right now. I feel comfortable with the starters we have. If we get to the point where we're not comfortable with them, then that might be something we explore.
"But I will tell you that, right now, I'm happy with our guys the way we are right now, unless something changes. I think we've got other fish to fry right now."
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.