The investigation results show that the returned bone screwhead is broken off, so the reported event could be confirmed.Because the other screwhead was not returned, it is not possible to confirm the reported event for that particular screw, and so no visual, functional, or dimensional inspection was performed on the 2nd screw.The (measurable) dimensions of the returned screwhead are in accordance with the specifications.Because a fragment of the screw is broken off and was not returned, the chemical composition was tested by edx analysis, which conforms to the specification tial6v4 (ti grade 5).The investigation shows that the screw was damaged by too high torsional and tensile forces, whereas the torsional forces prevailed during the insertion.The fracture surface of the screw shows the typical concentric flow structures of a ductile torsional breakage, as well as, honeycomb structure of a ductile forced rupture caused by high tractive forces.The investigation with sem shows on the fracture surface the typical honeycomb structure of a ductile forced fracture resulting from high torsional forces.The bottom surface of the screw head shows friction traces that point to the fact that after the screw contacted the plate and was already fully tightened it was forcibly further turned.No lot numbers were provided, thus a review of the specific manufacturing batch records and related quality documents (manufacturing documents, inspection plan, inspection drawing, and release report) cannot be performed.Therefore, it is also not possible to determine the quantity released for distribution within the affected lots.To obtain more details about the complained event, the sales rep was contacted.It was reported that the plate was cut into washers and the washer was put on the screw to help keep the medpor from backing out around the screw.The scrub tech in the case was dipping the screw in bone wax to help keep the washer from falling off.Furthermore, the sales rep indicated that the threads of the screw might be filled with bone wax, and so when they tried to insert the screw there was no room in the threads for the medpor or bone.According to stryker cmf¿s material expert, most likely the wax had no influence on the breakage of the screw.Based on the investigation and the corresponding statistical evaluation there is no indication for an incorrectly working product or any systematic design, material, or manufacturing related issue.Therefore, no further corrective and/or preventive actions are deemed necessary at this time.The complaint is added to the complaint trend.
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