Block also notes that Kirill Gotovets is likely out until the playoffs, goaltender Mark Visentin is done for the season and Jay Harrison has a concussion.
Hartman, who was the Hawks' first-round pick in the 2013 NHL Draft, likely suffered the injury when he blocked a shot against the Lake Erie last Thursday, according to Block. The 21-year-old forward recorded his first NHL career point with an assist earlier this season with the Hawks during a three-game call up stint. The West Dundee, Ill. native has scored 14 goals and 20 assists in 60 games with Rockford this season.
Gotovets, 24, has tallied two goals and 13 assists in 61 games in his first full pro season in Rockford.
Visentin, who signed a one-year deal in July, is 4-6-2 with a .906 save percentage and 2.60 goals-against average in 13 games. With Visentin out and Michael Leighton up with Chicago the goaltending position is in flux. Rockford head coach Ted Dent will have to turn to Drew MacIntyre or Mac Carruth, who posted his second career AHL shutout with a 1-0 over the Chicago Wolves on Wednesday in Rosemont.