It was reported that the patient had fusion with implants approximately one year ago with unknown surgeon.Patient subsequently fell at work and when an xray was taken, it showed the shafts of both s1 screws bilaterally had sheared off from the head.Posterior hardware removal l5/s1 was performed.Because there was already bony fusion, all implants were removed without replacement.
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Visual examination of the returned device revealed the shank was fractured off the screw head.Screw shank was not returned.Device was subsequently sent for fracture analysis.Optical imaging found two surface morphologies, a smooth region and a grainy/rough region with progression lines which are indicative of fatigue failure.A trend analysis was conducted.No emerging trends were found requiring further actions.The root cause cannot be positively determined from the sample and the information provided.However, based on the evaluation, the possible cause of the breakage is fatigue failure of the screw and inability of the screw to bear the load or the effect of the fall by the patient which will cause the shafts of the screw to break.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 were found, 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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