Texans rookie offensive lineman Tytus Howard left the game against the Lions on Saturday late in the first half and hasn't returned.
The first-round draft pick from Alabama State walked off the field to the locker room under his own power with trainers to get checked out.
Meanwhile, second-round cornerback Lonnie Johnson Jr. isn't playing and didn't dress out for the game. Johnson practiced all week without incident and he was expected to play in the game.
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