Rondo suffered the injury when he fell at his home on Thursday night and is expected to miss six to eight weeks, according to the release.
Rondo, 28, has averaged 11.1 points and 8.4 assists over eight seasons with the Celtics. Last season he posted averages of 11.7 points and 9.8 assists.
The Celtics, which went 25-57 and missed the playoffs in 2013-14, open the upcoming season Oct. 29 against the Brooklyn Nets.
- Chris Johnson