North Melbourne key defender Scott Thompson's AFL season is over after medical staff decided he should not risk further bruising to his lungs.
Thompson was injured when he crashed to the ground after a marking contest late in the game against Adelaide in Round 20.
Kangaroos medical services director Steve Saunders said scans showed he copped substantial bruising to some lung tissue.
"Until that contusion subsides, he can't be cleared to play again," said Saunders on the club website.
The concern is, the same tissue could bleed again and more damage could be done to his lung and obviously that wouldn't be good for him at all."
Saunders said that if the Kangaroos were in the finals race, Thompson would be a chance to return.
"The specialist indicated this is normally a four-week injury," he said.
"That's the amount of time it takes for the tissue to heal and be safe to the point of being able to withstand another contusion.
"So he's actually safe now to exercise heavily and to put himself through a fair bit of exertion but it's other knocks we're concerned about."
The 27-year-old Thompson has had a career-best year with the Kangaroos and is ranked sixth in the AFL for rebound 50s.
