The tests showed no structural damage, Putkonen said Monday night.
"It just showed inflammation," he said.
He'll undergo a program of rest and medication to try to get back to pitching shape.
The Tigers placed Putkonen on the 15-day disabled list Monday, opening a spot for slugger J.D. Martinez to join the roster and restore the bench to full strength. Detroit had gone with an extra reliever over the weekend for depth. Putkonen's move to the DL means Justin Miller, called up Friday as the extra reliever, is staying put.
Putkonen pitched just twice all season, most recently last Friday, when he gave up seven runs on five hits against the Angels. His inactivity was more about the strength of the Tigers' starting pitching than it was about Putkonen's health.
That said, Putkonen's velocity has been down this year, from an average fastball just over 95 mph the past coupleof seasons to just under 93 mph in limited work this season. His fastball Friday averaged 92.78 mph, according to brooksbaseball.net.
"I thought from not pitching, it would've gone away," Putkonen said. "But I felt it, especially on the breaking ball."
Jason Beck is a reporter for MLB.com. Read Beck's Blog and follow him on Twitter @beckjason. This story was not subject to the approval of Major League Baseball or its clubs.