BRISBANE Lions ruckman Matthew Leuenberger will miss at least 12 weeks after an arthroscope performed on Tuesday revealed damage to the lateral meniscus in his left knee.

Leuenberger sustained the injury in the first quarter of the Lions’ victory over the Sydney Swans on Saturday night.

He returned to play out most of the game but fears about the extent of the injury were confirmed by the procedure.

In a statement the club said that the injury was “immediately” repaired by the surgery, and that the 20-year-old is expected to make a full recovery.

Nevertheless, Leuenberger’s recovery will keep him away from football until at least round 15.

The young tall missed the last seven games of the 2008 season with a knee injury after playing 10 games earlier in the season.

He was taken with pick four in the 2006 draft and had been preferred to teammate Jamie Charman as the Lions number one rucking option this season, averaging 17 hit-outs and nine disposals in the first three rounds.