The injury occurred with 2:22 remaining in the second overtime of the Blazers' 148-144 triumph Monday at Moda Center in Portland. Blazers forward Maurice Harkless put up a shot near the rim and Nurkic went up for a rebound on the play.
Nurkic was able to get a follow-up shot, but missed the attempt. He came down on top of a defender and twisted his foot to the side, before his leg gave out and bent unnaturally toward the bottom.
The 7-foot center was taken to a hospital after the game. Portland announced Nurkic sustained compound fractures of his left tibia and fibula. There is no timetable for his return to basketball activity.
"Nurk is such a great dude, you hate to see him have to go through something like that," Blazers star Damian Lillard told reporters. "He was having his best season in the NBA ... Seeing something like that happen to him personally, you never want to see for your friend or your teammate."
Nurkic averaged 15.6 points, 10.4 rebounds and 3.2 assists in 72 starts this season for the Blazers. He also shot 50.8 percent from the field.
"Seeing one of your brothers go down like that, I just don't know what to say," Blazers big man Enes Kanter said. "But tonight I'm just going to go home and pray for him because this is way bigger than basketball."
The Blazers battle the Chicago Bulls at 8 p.m. Wednesday at the United Center in Chicago.