Helenius (upper body) was placed on injured reserve by the Sabres on Thursday, Mike Harrington of The Buffalo News reports.
Helenius sustained an upper-body injury in late October, and the Sabres announced afterward that the 20-year-old was considered week-to-week. As a result, it isn't very surprising to see him land on injured reserve, and while it isn't yet clear when he'll be able to return, his move to IR shouldn't impact his timetable.