The surgery is scheduled for Oct. 24 in Los Angeles, and there is no announced timeline for his return.
Exum was injured in a preseason game against the Phoenix Suns on Oct. 6 when he landed awkwardly on the floor.
The 2014 No. 5 overall pick was hoping to have a career year as a restricted free agent. Coach Quin Snyder was playing Exum as a point guard and off guard this season, and there were additional opportunities with the departures of Gordon Hayward and George Hill.
This is the second significant injury of Exum’s short career. A torn ACL kept him from playing in 2015-16.
Exum averaged 6.2 points, 2.0 rebounds and 1.7 assists last season.