He's expected to be out a minimum of three weeks, according to the Denver Post.
Gallinari turned in one of his best games of the season Saturday in a win over Indiana as he scored 19 points, including a 3-pointer to spark a critical fourth-quarter run.
Gallinari is averaging 7.8 points in 18.8 minutes this season.
He was back on the court this year after missing nearly 18 months with a torn ACL in his left knee that required three surgeries.
The banged-up Nuggets will be without guard Randy Foye (right quadriceps) and center JaVale McGee (lower left leg strain) on Monday at Charlotte. Forward Darrell Arthur is questionable with a leg injury.
The Associated Press contributed to this report.