McKinnon hurt his lower back and missed the last game against Carolina. He was already ruled out for Sunday, when the Vikings host the New York Jets.
The Vikings made the move on Saturday, signing practice squad defensive end Justin Trattou to the active roster to fill McKinnon's spot. Safety Ahmad Dixon was signed to the open spot on the practice squad.
McKinnon rushed for 531 yards over his last eight games and averaged 4.8 yards per attempt for the season, becoming the primary ball carrier after Adrian Peterson had his off-field issues. McKinnon was a third-round draft pick out of Georgia Southern.
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