Porteous, who claimed gold in the men's halfpipe in China in February, went under the knife to repair a ruptured anterior cruciate ligament (ACL) two weeks ago.
"A month ago, I ruptured my ACL and have had surgery two weeks ago,'' Porteous revealed in a video on his Instagram account.
"So it's been a pretty quick process but definitely not what I was wanting to do to end off my season."
The 20-year-old from Wanaka burst into the public eye back in 2018, becoming just the second Kiwi athlete to claim a Winter Olympics medal when he took out bronze on the halfpipe. He backed that up this year, going two places higher on the podium.
While he didn't provide any information on how the injury occurred, Porteous said he was hopeful of being back in competition next January.
"I'm not going to post any gym stuff or post any rehab, it's not something I really want to do," he added.
"It's injury and injuries are a part of freestyle skiing, and that's my personal thing to deal with."
