Lions coach Jim Caldwell said after the game that Hyder suffered a "significant Achilles injury." He didn't want to say much about a diagnosis until doctors finish tests, but a source told ESPN's Adam Schefter that the Lions fear that Hyder tore his Achilles.
When asked if Hyder's Achilles was torn, Caldwell said they are waiting on official word from the doctors.
"It's significant. The doctors, that's the initial impression," Caldwell said. "When we have something certain, we'll release it. But I'll tell you it's significant."
Hyder had been pressuring Colts quarterback Scott Tolzien when he appeared to lose his footing and fell to the ground. He immediately grabbed the back of his left leg around his ankle and was on the ground being looked at by trainers for several minutes before the cart came out. He put no pressure on the leg as he went onto the cart.
FOX2 (Detroit) reported on television that Hyder suffered a lower leg injury and would be out for the game.
The 26-year-old was a breakout player for the Lions last season, going from a roster afterthought in the beginning of the 2016 preseason to leading the team with eight sacks by season's end. It was a year ago at Lucas Oil Stadium, where he suffered the injury Sunday, that he had a breakout performance with three tackles and two sacks in Detroit's 2016 season opener.
Hyder is expected to be a starter for the Lions this season opposite Ezekiel Ansah, who has been on the PUP list since the beginning of training camp.
The Lions lost even more defensive line depth in the second half, as hybrid end/linebacker Brandon Copeland left the game with a shoulder injury and did not return, according to the Detroit Free Press. Copeland entered the game after Hyder's injury in the first quarter and had been pushing for a depth end spot and to possibly be the team's starting SAM linebacker.