The team announced Monday that McCollum will be re-evaluated in a month.
McCollum suffered the injury while securing an offensive rebound during the fourth quarter of Monday's win over the New Orleans Pelicans. He was not immediately removed from the game. McCollum also missed significant time last season after breaking his foot during preseason camp.
Over 11 games this season, the 6-foot-4, 200-pound guard has averaged 5 points and 1.1 assists in 13.1 minutes while shooting 37.2 percent from the field and 45.8 percent from three-point range. Portland drafted McCollum with the No. 10 pick in the 2013 draft out of Lehigh.
The Blazers (8-3) host the Chicago Bulls on Friday.
- Chris Johnson