The only injuries I'd worry about are the guys trying to tackle Gronk.
I've only seen one play in which he risked injury to himself, and that was when he got flipped and landed on his neck. Nothing else he does is reckless, he just uses pure strength and athletic ability to out-muscle others to the ball. He doesn't do fancy spin moves and jukes or anything like that. All of his direction changes are just him running at an angle.
The only thing worrisome is how many defenders go for his legs, and so far the only thing to ever hurt Gronk was the endzone knocking the wind out of him.
He does NOT play dangerously on a regular basis.