"It is anticipated that the injury will require surgery that will sideline him for the season," Coach Dave Wannstedt said in a statement late Friday. "Further details of his condition will be available following the conclusion of the surgery."
Boston was running a pass route and his knee appeared to buckle after he planted his foot. He was not hit on the play.
It was the second major loss for the Miami offense during training camp. Running back Ricky Williams announced his retirement soon after camp began.
Boston spent last season with San Diego, where he had 70 catches for 880 yards with seven touchdowns.
Exploding whale video goes viral on Internet
Wisconsin business offering 'therapeutic cuddling' forced to close