McGruder is slated to undergo surgery next week.
It wasn't clear when the 26-year-old McGruder suffered the injury. He played 25 minutes in Wednesday's preseason victory over the Washington Wizards.
McGruder averaged 6.4 points in 78 games, including 65 starts, last season in his first NBA campaign. McGruder went undrafted out of Kansas State in 2013.
--Indiana Pacers forward Glenn Robinson III will undergo surgery on his injured left ankle and is expected to be sidelined until mid-December, ESPN reported.
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, including 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.
--The Brooklyn Nets exercised the 2018-19 contract options for D'Angelo Russell, Rondae Hollis-Jefferson and Caris LeVert.
Russell, the No. 2 overall pick of the Los Angeles Lakers in the 2015 NBA Draft, was acquired by the Nets in June. He averaged 15.6 points, 3.5 rebounds, 4.8 assists and 1.4 steals last season.
Hollis-Jefferson, acquired in a draft-night trade after he was selected No. 23 overall by Portland in 2015, appeared in a team-high 78 games last season and averaged 8.7 points and 5.8 rebounds.
LeVert was acquired from Indiana after the Pacers selected him with the 20th overall selection in 2016. He started 26 of 57 games last season, averaging 8.2 points, 3.3 rebounds and 1.9 assists.
--The Denver Nuggets have officially signed guard Gary Harris to a contract extension, the team announced.
As reported earlier, Harris agreed to the four-year, $84 million extension on Saturday.
Harris, 23, averaged 14.9 points, 3.1 rebounds and 2.9 assists and made 50.2 percent of his field goals last season.
--The Memphis Grizzlies announced plans to retire the number of Tony Allen in the future.
Allen departed the team this summer and signed a one-year deal with the New Orleans Pelicans for the veteran's minimum of $2.3 million.
Allen averaged 8.9 points and 4.3 rebounds per game during his seven seasons with the Grizzlies. He also earned first- or second-team All-Defensive honors in six of those campaigns.