Anaheim, CA (Sports Network) - The Anaheim Angels announced that outfielder Garret Anderson was diagnosed with arthritis in his shoulders, upper back and neck.
Anderson has been on the 15-day disabled list with upper back stiffness since April 22.
"It's encouraging to get a hard diagnosis," manager Mike Scioscia said. "At least it's something that is firm and can lead us to a course of action and treatment that will get him better."
There is no timetable for the All-Star's return, but he is expected to take medication and begin rehab in a pool within the next week.
"I don't know when it's going to be, but I expect him to be back helping us this season," Scioscia said.
In 15 games this season, Anderson is batting .339 with 12 runs scored, four doubles, two home runs and five RBI. He is the club's all-time leader in hits and batted .315 with 29 homers and 116 RBI in 159 games last year.