Ryan Tannehill was diagnosed with ACL and MCL sprains in his left knee but no tears.
Adam Gase said surgery is not required and that the team doesn't have an exact timetable for Tannehill's recovery, but the quarterback is expected to miss at least the next couple of games.
"This is not going to be one game," Gase said. "It's going to be longer than that."
Campbell's hit on Tannehill has drawn criticism on social media but Bruce Arians defended his player Monday and said Campbell was blocked into Tannehill.
Arians said Campbell's hit "was just a football play."
Matt Moore will start for the Dolphins.