Hansen picked up the injury in last Thursday's friendly win at Salford and may need surgery.
Wigan have already lost Hansen's second-row partner Gareth Hock, who was ruled out for the start of the season with a shoulder injury before he moved on loan to Widnes.
"It looks like Harrison will need an operation on his wrist," Wigan coach Shaun Wane said. "I'm not sure of the exact timescale at the moment.
"He's struggling in the gym with his grip on the weights and for him to miss any training means it must be serious because he's a tough competitor.
"Harrison has been great in pre-season and any time on the sidelines is a blow for him and for us."
Wane also revealed that back-row forwards Chris Tuson (dead leg) and Sean O'Loughlin (calf) could also miss Saturday's Ben Westwood testimonial game at Warrington but should be fit for the Super League opener at Salford on Friday week.