I WAS REAR ENDED WHILE STOPPED IN HEAVY TRAFFIC ON A MAJOR HIGHWAY. I WAS SITTING ON THE DRIVERS SEAT. MY CAR SEAT HAD A SEAT BACK FAILURE AS SOON AS THE AT FAULT CAR IMPACTED ME. MEANING INSTEAD OF HOLDING ME IN PLACE IT JUST FLIPPED BACK WITH MY HEAD AND SHOULDERS ENDING ON BACKSEAT. I WAS PUSHED INTO THE CAR IN FRONT AND THE AIRBAG DIDN'T DEPLOY BUT THE HEADRESTS DID. I SUSTAINED HEAD BACK AND NECK INJURIES AS WELL AS BRUISES ON THE BACK OF MY CALVES FROM HITTING THE REAR/FORWARD BAR ON BOTTOM OF SEAT. AS THE CAR IMPACTED ME MY PELVIC AREA WAS TRUST SLIGHTLY BECAUSE THE SEATBELT IN PLACE DIDN'T HOLD ME AS I BASICALLY SLID A BIT OF IT WHEN BENDING BACKWARDS ON MY SEAT. THE VEHICLE WAS STATIONARY ON DRIVE BUT MY FOOT FIRMLY PLANTED ON BRAKE. THE DRIVER WHO HIT ME PUSHED ME INTO THE FRONT SEAT BUT BY THE TIME I HIT IT I WAS ALREADY ON MY BACK, SO CAR SEAT FAILURE HAPPENED ON REAR IMPACT, BEFORE I HIT CAR IN FRONT. SINCE WE WHERE IN THE MIDDLE OF THE HIGHWAY I HAD TO MOVE THE CAR TO THE RIGHT SHOULDER AND WHILE DAZED PULLED UP SIDE LEVER TO BRING CAR SEAT BACK, AND IT DID. SO THIS DEFECT IS BASICALLY INVISIBLE UNLESS YOU ACTUALLY EXPERIENCE IT.