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The reported event could be confirmed, since a displacement of four (4) locking screws could be confirmed based on the pictures received.The device inspection revealed the following:
the distal lateral femur plate, five (5) locking screws, one (1) cancellous screw and four (4) cortex screws were returned for evaluation.Based on the provided information was there no issue with the bone screws, therefore are the cortex screws and the cancellous screw considered as concomitant devices.Based on the received x-rays it was possible to identify the three (3) locking screws that backed out of the plate.The returned 85mm, 95mm and 105mm screws are the affected devices.The visual inspection of these screws has shown that all screw heads are slightly damaged in a similar manner, especial the first thread flanks are slightly flattened.This could be an indication for an excessive contact between the screw and the plate during the insertion, for example by an out of the 30° cone insertion.But it can in retrospective also not be excluded that the damages occurred in-situ due to friction between the screw and the plate.A review of the device history for the reported lot did not indicate any abnormalities.No corrective actions are required currently.A review of the labeling did not indicate any abnormalities.No indications of material, manufacturing or design-related problems were found during the investigation.No product related issue could be detected during the investigation.Based on investigation, the root cause was most likely attributed to a user related issue, since the visible marks at the also received plate indicate a drilling out of the 30° cone of the predetermined hole trajectory of the universal holes.Due to the damage at the plate was a proper locking of the screw not possible anymore, which contributed to the back out of the three (3) locking screw.However, the exact root cause could not be defined since no pre- and intra-operative x-rays in different planes, operation reports, detailed patient details, history and activity were provided.There are many factors that could have played a role too, like screw insertion torque, fracture situation, patient condition, especially in relation to bone quality and activity.If more information is provided, the case will be reassessed.
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