McDonald was second on the team last year with 51 three-point field goals and averaged 7.0 points per game.
He led the team in three-point shooting at 38.1 percent. He scored a career-high 17 points against Long Beach State, one of 10 games last year in which he scored in double figures.
"I just hate this for Leslie and his family," says head coach Roy Williams."He's worked so hard this off-season and he told me he was really playing well.
"We'll certainly support him as he works to get back on the floor, but we will miss his play on both ends of the court."