Larry Brooks of the New York Post reports Stepan's injury did not involve any contact, he "simply fell to [the] ice."
Stepan, 24, has never missed a game in his four-year NHL career. He tallied 57 points last season and another 15 points during the Rangers' playoff run.
The Rangers open the regular season in St. Louis against the Blues on Oct. 9.
- Dan Gartland