Weatherspoon's injury happened late in a 80-68 win over Boise State on Friday in a game in which he scored a career-high 25 points.
"I can't even begin to tell you how bad I feel for Q," MSU coach Ben Howland said in a news release. "He's worked so hard to get where he's at, but he knows he has the support of everyone on this team, and I expect him to fully recover and be back with us full strength next year."
Weatherspoon is a 6-foot-4 sophomore and is averaging a team-high 18.8 points per game to go along with 5.0 rebounds and 2.5 assists per game.
The Bulldogs (3-1) next play Friday at home against Lehigh.