Knee operations have ended the AFL season for Port Adelaide ruckman Dougal Howard and Brisbane midfielder Tom Bell.
Howard damaged an anterior cruciate ligament in Saturday's loss to Fremantle and on Monday he underwent a knee reconstruction.
"It's too early to say how long the rehab will actually take, but often it's a return around the 12-month mark," said Port high performance boss Darren Burgess.
Bell missed the weekend's loss to West Coast because of a medial meniscus tear and the club has confirmed he will undergo season-ending surgery on Tuesday.
Teammate Ryan Harwood could also be out of action for the rest of the year because of the strained posterior cruciate ligament he suffered against the Eagles.
Fellow Lions backman Tom Cutler has a hamstring injury and will sit out Saturday's match against Richmond at the MCG.
