Reds manager David Bell said Wednesday that Martini will likely be out until September after undergoing surgery to repair ligament damage in his left thumb, Mark Sheldon of MLB.com reports.
Martini landed on the 10-day injured list over the weekend with the injury and has opted to have it surgically repaired. He's expected to come off the IL before the end of the season, but a precise target date for his return won't become clear until he's able to begin a minor-league rehab assignment.