Concomitant medical devices: ann ph nail rt9x160mm; item# 47249616009; lot# 3067307, ann blunt tip screw 4x48mm; item# 47248604840; lot# 3068481, ann blunt tip screw 4x42mm; item# 47248604240; lot# 3076739, ann blunt tip screw 4x48mm; item# 47248604840; lot# 3073797, ann cort bone screw 4x24mm; item# 47248612440; lot# 3081954, ann cort bone screw 4x26mm; item# 47248612640; lot# unknown.Foreign source: germany.Multiple mdr reports were filed for this event, please see associated reports: 0009613350-2022-00272, 0009613350-2022-00273, 0009613350-2022-00440, 0009613350-2022-00441.The products were returned for examination.Signs of wear on the threads of the blunt tip screws are minimal to non-existant, which is uncommon for migration cases.Additionally, the received nail has minimal scratches up until the proximal bore holes, where the 3rd most proximal hole has several scratches at the chamfer, likely originating from vibration or migration of the screw.The corelock mechanism is still contained within the nail.The cortical screws are inconspicuous.Review of the device history records identified no deviations or anomalies during manufacturing.Devices are used for treatment.Medical records in the form of x-rays were provided.The post-operative x-rays are ap views, with the humerus in one of the images being internally rotated.A serious fracture of the humerus is clearly visible.The lateral pre-operative image is not of much merit to the investigation, however shows an anterior dislocation of the humeral head.The second pre-operative image shows clear signs of humeral head necrosis.A possible screw migration can not be assessed due to the rotation of the humerus in comparison with the post-operative x-ray.Based on the investigation it could be assumed that further possible contributing factors to the migration of the screw might be multifactorial related to either patient condition, behavior or implantation procedure.Of note is the evident humeral head necrosis as seen on the x-rays, which likely caused or contributed to the reported event of screw migration.The cause of humerhal head necrosis however is unknown, but might be related to the severity of the humeral head fracture sustained prior to implantation of the devices.If and to what extent any of these aspects may have influenced the migration of the screw remains unknown.The design limitation of the corelock mechanism was also investigated as a potential contributing factor.However, biomechanical testing determined that the product performance is in an acceptable range in comparison with legally marketed similar devices.In conclusion, as the cause may be multifactorial an exact root cause could not be identified for the migration of the screw.If any further information is found which would change or alter any conclusions or information, a supplemental report will be filed accordingly.Zimmer biomet will continue to monitor for trends.
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