Also dealing with a bone bruise and joint inflammation, Gardner was administered a platelet-rich plasma and cortisone shot by Kremcheck, the Reds' orthopedist.
Agreeing with Dr. James Andrews' recommendation from Monday, Kremcheck believes the elbow will need three to four weeks of rest. Gardner will also wear an elbow brace to ensure he'll get the proper rest.
Gardner has been on the disabled list since making a diving catch at Yankee Stadium on April 17. He tried to rehab the injury twice but was shut down both times.
"I've done everything I can do, and the training staff has done everything it can possibly do over the last seven weeks to get me back out on the field," Gardner said earlier in the week. "It hasn't worked out the way we thought, but hopefully I'll be back soon."
In other news, the Yankees reinstated right-hander David Robertson from the 15-day DL on Thursday and optioned right-hander David Phelps to Class A Tampa.
Quinn Roberts is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.