A two-time Vezina Trophy finalist, Luongo was injured five minutes into Saturday's 3-1 victory at Pittsburgh and didn't put any weight on his left leg while being helped off the ice by teammates. He had an MRI exam Monday and the Canucks announced the diagnosis after consulting with team doctors.
Luongo was listed as week to week with an adductor muscle strain in his groin.
"We don't know, it's the first time I've had an injury like this," Luongo said just before Vancouver's game against Detroit on Monday night.
The Canucks' captain was tied for second in the NHL in wins with an 11-5-2 record. He was seventh in save percentage at .928 and 10th in goals-against average at 2.10 despite a slow start to the season in October.
Luongo dropped to the ice five minutes into Saturday's 3-1 win at Pittsburgh. By the time he had an MRI Monday he was confident he'd avoided the worst-case scenarios he first feared.
"Once you're in that kind of pain you always think of the worst right away and for the first 24 hours I was pretty worried," Luongo said. "But once I got up on Sunday and was able to come over to the rink and walk and stuff like that I realized maybe it wasn't as bad as I first thought."
In November, Luongo is 5-1-2 with a 95.9 save percentage. He leads the league with five shutouts, including three in a row from Nov. 4-8.
"This is a great challenge for our group," Canucks coach Alain Vigneault said. "Our players play real well in front of Curtis [Sanford], and Curtis is an experienced NHL goaltender. He'll do a good job for us."
Vancouver also recalled goalie Cory Schneider from Manitoba of the American Hockey League. Schneider, the Canucks' first-round pick in 2004, leads the AHL with a 10-1 record and 1.37 goals-against average. He was second with a .945 save percentage.
The 29-year-old Luongo started 14 straight games before Sanford made his first appearance in more than a month Thursday at Minnesota. Sanford then replaced Luongo in Pittsburgh on Saturday, stopping 45 of 48 shots overall to win both games -- his first victories since Dec. 12, 2007.
Sanford was 4-3-1 with an .898 save percentage last season, his first in Vancouver after seven seasons in the St. Louis organization, including a career-high 34 games and 13 wins with the Blues in 2005-06.