According to a report by Sports Hochi, Yuki Saito has an injury in his right shoulder that could, at worst, require surgery.
Saito was examined at a hospital at the end of last year and diagnosed with injury in his right glenoid labrum. He had it re-examined again earlier this month and was given the same diagnosis. He has continued tor rehab the shoulder, and has been playing catch and throwing balls into a net, but he has not been able to throw the ball very hard.
For now, Saito will head to spring camp in the hopes that the warmer temperatures will help with his recovery. But there is no timetable for when he will be able to toss a bullpen session. If his shoulder does not show signs of improvement, other options will have to be considered.
Worst case scenario: surgery that could sideline Saito for a prolonged amount of time.
Source: Sports Hochi 1/31/2013