ON 3/9/2020 AT APPROXIMATELY 4:30 PM WHILE DRIVING SOUTH ON INTERSTATE 55 JUST SOUTH OF SOUTHAVEN MISSISSIPPI WHEN THE PASSENGER SIDE HEADREST DEPLOYED SPRINGING THE HEAD REST FORWARD WITH CONSIDERABLE FORCE. MY WIFE WAS SITTING IN THE PASSENGER SEAT AT THE TIME AND WAS STRUCK BY THE HEADREST IN THE HEAD AND COMPLAINED THAT IT HIT HER HEAD SO HARD THAT IT HURT. WE WERE NOT INVOLVED IN AN ACCIDENT AT THE TIME AND WERE TRAVELING AT THE POSTED SPEED LIMIT. I HAD NOT HAD TO BREAK HARD OR ANYTHING. THE HEADREST JUST CAME APART. AFTER SOME RESEARCH I SEE THIS IS SUPPOSE TO BE A SAFETY FEATURE THAT WOULD OCCUR IN AN ACCIDENT. THERE WAS NO ACCIDENT. AFTER ARRIVING HOME I NOTICED A METAL PIN IN THE BOTTOM OF THE SEAT REST AND BROKE PLASTIC IN THE LOCATION WHERE THE PIN SHOULD BE LOCATED. NOW I AM CONCERNED THAT THE DRIVERS SEAT MAY DO THE SAME THING AND CAUSE AN ACCIDENT.I ALSO NOW HAVE THE ISSUE OF A COSTLY REPAIR FOR A DEFECTIVE DESIGN FLAW.