It was reported that there was an issue with sw346t - s4 polyaxial screw 6.5x45mm canulated.According to the complaint description, the connection of the screw was not possible during surgery.Type of surgery: l4 / 5 plif, degenerative spondylolisthesis.The doctor pointed out that the driver was moving and unstable while inserting the screw 6.5 x 45 mm (sw346t) to the right of l5.Therefore, when the tip of the screw crossed the posterior edge of the vertebral body, the screwdriver was once removed from the screw and reconnected.When the doctor checked the front and side of the screw after installing it, it was inserted slightly downward, so i had to remove the screw and reinsert it.When connecting the driver to the screw, it was pointed out that it could not be connected properly, so when we checked the surgical field, we found that the polyaxial insert had come off.The screw was removed with a screw remover, and another screw 6.5 x 45 mm (sw346t) was newly inserted to the right of l5.The operation was completed successfully.An additional medical intervention was necessary.Additional information was not provided.Additional information has been requested but not yet received as of this report.Additional patient information is not available.The adverse event is filed under aag reference (b)(4).Involved components: fw174r - s4 screw driver w/shank tip - lot unkown, fw270r- s4 screw driver f/canul.Polyaxial screws - lot unknown.
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Investigation results: visual investigation: the complained screw arrived in detached condition in common with three screwdriver.In the first step we made a visual inspection of the detached pedicle screw.The threated body shows no damages or defects.The hexagon in the head of the screw shows heavy deformations at the upper edge, most probably caused by a not correct / complete attached screwdriver.This in conjunction with levering leads to a deformation of the insert, especially of the nose which fixes the insert in the body.Unfortunately the insert of the screw was not enclosed.In the next step we investigated the tip of each enclosed screwdriver.Here we found more or less wear and damages on each tip.Batch history review: the device quality and manufacturing history records have been checked for the available lot number and were found to be according to our specifications valid at the time of production.Review of the complaint history revealed that no similar complaints have been filed against products from this batch number.The review of risk assessment revealed that the overall risk level (severity 6(10) x probability of occurrence 2(10)) according to din en iso 14971 is still acceptable.Conclusion and measures / preventive measures: based upon the investigation results a clear root cause conclusion cannot be drawn.There is no indication for a material-, manufacturing- or design-related failure.Based upon the investigations results a capa is not necessary.
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