The Red Sox announced Tuesday that Kelly underwent a successful ulnar nerve transposition revision in his right elbow, Jen McCaffrey of The Athleticreports.
The procedure was performed by Dr. Jeffrey Dugas at The Andrews Institute in Birmingham, Alabama. Kelly has no timetable for a return at this point, but the right-hander told reporters near the end of April that his hope is to return in four months. If there are no setbacks, Kelly could be a late-innings option for the Boston bullpen near the start of September.