Robinson sustained the injury while driving to the basket during a scrimmage in practice on Sept. 29.
The 6-foot-6, 222-pound Robinson, the son former NBA star Glenn Robinson, averaged a career-high 6.1 points and 3.6 rebounds in 69 games (27 starts) last season. The 2017 NBA slam dunk contest champion shot 39.2 percent on 3-pointers.
With Paul George traded to Oklahoma City, Robinson is expected to play a more prominent role this season.
Robinson was a second-round draft pick of the Minnesota Timberwolves in 2014 after leaving Michigan following his sophomore season. The 23-year-old had stops with Minnesota and the Philadelphia 76ers before signing with the Pacers for the 2015-16 season.