Vaughn suffered the injury in the second half of UNLV's victory over Fresno State on Tuesday. The former five-star recruit from Minneapolis is UNLV's leading scorer with 17.8 points per game.
A statement from head coach Dave Rice said Vaughn will be out indefinitely with the possibility of a return for the Mountain West conference tournament, which runs March 11-14 in Las Vegas.
"We are very disappointed for Rashad," Rice said. "He is having a great freshman year and has been an extremely valuable player on our team. We know he will work very hard to get back on the court as soon as possible and we will support him in every way."
Vaughn, a 6'6, 210-pound guard, has had two 30-point games and nine 20-point games this season. He started and appeared in 23 of UNLV's 24 games.
UNLV (14-10) is eighth in the MWC with a 5-6 conference record.
- Mike Fiammetta