BOSTON -- It has been suggested for months that second baseman Aaron Hill could miss the remainder of the season. Now the club has made it official: Hill will not return to Toronto's lineup until 2009.

Hill has been sidelined with post-concussion syndrome since late May and hasn't reached a point where he's near being ready to return. With the season winding down, the Blue Jays simply don't have enough time to get him back into game shape.

"From an analysis standpoint, he's doing better," general manager J.P. Ricciardi said. "But from an 'OK to go out and run around and do everything' [standpoint], he's not even close to that. So he's done for the year, which is unfortunate."

Hill returned to Pittsburgh earlier this week to be re-evaluated through the University of Pittsburgh Medical Center's renowned Sports Medicine Concussion Program. Ricciardi said the test results indicated that Hill has shown progress in his recovery, but not nearly enough to consider coming back before the end of this season.

"He just visited the doctor back in Pittsburgh," Ricciardi said. "They said he's made significant improvement, but there's just not enough time to get him ready, and he's still not able to even do physical things."

On May 29, in Oakland, Hill was struck on the side of the head during a collision with shortstop David Eckstein on a play in the seventh inning. Hill was initially considered day-to-day, but he landed on the disabled list after his condition didn't improve.

"It's uncharted waters with the head," Ricciardi said. "It's amazing that as far as they've come, they still haven't come far enough to be able to pinpoint [how long it takes to return]. You guys have all seen the hit. It's not like it was a violent hit where you sat there and said, 'Whoa.' "

At the time of the injury, Hill was batting .263 with two home runs and 20 RBIs in 55 games for the Blue Jays, who signed him to a four-year contract worth $12 million in April. Last season, Hill hit .291 with 17 homers, 47 doubles and 78 RBIs in 160 games while playing strong defense for Toronto.

The 26-year-old Hill has returned home to Florida -- near Toronto's Minor League facility in Dunedin -- and Ricciardi said there's no timetable as to when Hill can move beyond the light activities he's been cleared to do. The Jays can only hope he will be completely recovered in time for next season.

"He's probably not going to do anything until Spring Training," Ricciardi said. "Obviously, he'll do his winter stuff and get ready, but he's done for the year."