Bills rookie linebacker Tony Steward, a sixth-round pick, could miss a few weeks after hurting his knee in the first half.
Coach Rex Ryan said Marquise Goodwin is out indefinitely after breaking his ribs late in the first half of a 43-19 preseason win over the Pittsburgh Steelers on Saturday.
Coach Mike Tomlin would only say Hartley's injury "doesn't look good."
The Steelers signed the seventh-year player on Aug. 11 after Shawn Suisham sustained a season-ending injury to his left knee in the Hall of Fame game against Minnesota.
Goodwin had made a 19-yard catch and cut into the middle of the field and was tackled by linebacker Ryan Shazier and defensive lineman Ethan Hemer.

ORCHARD PARK,Cheap Jerseys Free Shipping, N.Y. (AP) — The Buffalo Bills' already banged-up group of receivers has lost another player.
Goodwin lay on the turf for several minutes while being treated by trainers,Cheap NFL Jerseys Wholesale. And he eventually needed to be helped up by running back Fred Jackson before Goodwin was slowly taken to the Bills locker room,Cheap NFL Jerseys China.
The Steelers could be searching for another kicker after Garrett Hartley hurt his right hamstring during a kickoff in the first quarter,Cheap China Jerseys.
The Bills played the Steelers without their three starting receivers: Sammy Watkins (gluteal muscle/hamstring), Percy Harvin (hip) and Robert Woods (tightness).
All three are expected to be ready for the start of the season. Another receiver, Chris Hogan, is sidelined for two to four weeks with a sprained ankle.
Tomlin said rookie linebacker Bud Dupree,China Jerseys Cheap, the team's first-round pick,Stitched NFL Jerseys, did not return because of a sore foot.
Bills starting cornerback Stephon Gilmore did not return after hurting his right shoulder while tackling receiver Markus Wheaton. Tests however revealed that Gilmore did not sustain a concussion.