Attempted to place h/h link on c5.Placed inner nut.Did not torque.Placed xlink then outer nut.Hand tightened inner nut.White knuckle, then torque outer nut, then attempted to torque inner but it would not get tight/torque.Removed xlink construct.Threads of inner nut was in poly screw.Repeated with new implants and same sequence same failure.Left construct without xlink.
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(b)(4).Three (3) mntr h/h x-conn inner screw were returned for evaluation.The inner screw featured most of its thread torn off from the start of the body with drive feature damaged as well while the outer nut was also found to have its thread damaged at its start.This damage may have occurred due to cross threading the outer nut on the inner screws upon insertion.Tightening an outer nut while it is cross threaded places an unexpectedly high amount of force on the threads of bot the nut and the inner screw, resulting in them being damaged or torn.A review of the device history record was conducted.No issues were identified during the manufacturing and release of this product that could have contributed to the problem reported by the customer.No emerging trends were found requiring further actions.A definitive root cause of the outer and inner screws¿ threads being torn cannot be determined from the samples and the information provided.A potential root cause may be due to inadvertently cross-threading of the screws during insertion and subsequent attempts to tighten the screws, placing enough force on the threads could have tear them off on one side before building up stresses again on the next rotation.As there has been no issue identified in the manufacturing or release of the device that could have contributed to the problem reported by the customer and no systemic trends requiring immediate action have been observed, this complaint file will be closed with no further action required.If information is obtained that was not available for the initial medwatch, a follow-up medwatch will be filed as appropriate.
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