The 34-year-old injured his hand while trying to lay a tackle, and immediately went off the field and down into the West Coast rooms.
Petrie returned to the field with his hand heavily strapped and played out the remainder of the contest, but coach Adam Simpson said post-game that the injury would need surgery.
"What a tremendous effort by Drew. He fractured his hand in the second minute and played out the game." Adam Simpson pic.twitter.com/bEu1msSIOc
The surgery is set to see Petrie on the sidelines for several weeks, and Simpson also confirmed back up ruckman Jonathan Giles will be recalled from East Perth.