Atec received a complaint on (b)(6) 2021 that reported while removing the expansion shaft from the expanded osseoscrew, the expansion shaft (referred to as the stylet) broke off at the threads.The tip of the expansion shaft remains entrapped in the implanted osseoscrew.Although the products were not returned for evaluation, an investigation was conducted by the project engineer and determined that this particular occurrence was ultimately a result of user error.The surgical technique provides instruction for releasing the expansion shaft after the screw has been deployed "turn the t handle a full rotation counterclockwise to relieve built up tension.Using the gold release feature on the proximal end of the expansion t handle, press the gold retention ring to release the expansion shaft.After the shaft is released, rotate the shaft counterclockwise to unthread it from the osseoscrew." when the internal tension built up from expanding the screw is not relieved by turning the t-handle counter clockwise before removal attempt, a torsional shear failure of the expansion shaft can occur.This is caused by the extra grip on the expansion shaft threads if the shaft is being pulled tightly.
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