We have inspected the dhf of the affected lot including material certificate and the batch was processed through the normal manufacturing and inspection operations with no non-conformances or rework noted.The article met all dimensional and visual criteria at the time of release with no issues documented during the manufacture that would contribute to this complaint condition.The verification of the returned devices showed no deviations.To check the 4 cortical cores for possible malfunction (burr in bore), the cannulation was visually inspected and a guide wire of the affected lot number was inserted through.The guide was very smooth and no deviation was detected in this regard.The detached guide wire was heavily contaminated and tapered towards the broken surface.At the taper, deformation marks but no broken pieces (except for the vertical fracture surface) can be seen.Near the fracture surface, the guide wire appears bent.During root cause analysis, a test was performed with another guide wire, which revealed that the guide wire had not fractured but may have been drilled off by an oblique initial hole in the bone through the cortical notch.The cortical cores used during surgery were also checked.There were no deviations that led to the incident.In order to avoid stresses / bending of the guide wire and thus a significant increase in the risk of damage or even breakage of the guide wire due to cannulation with the cortical countersink, care should be taken during use to ensure that drilling is performed with the cortical countersink at the same angle to the previously inserted guide wire.The broken guide wire exhibits a comparable defect pattern as in the test, thus demonstrating that drilling not in line with the axis and the associated "drilling off" of the guide wire could be a possible cause of breakage.Any deviation in the angle from the cortical countersink to the guide wire increases the risk of iatrogenic failure of the guide wire.Thus, there are several possibilities for the cause of failure.Even though the experiment showed that this could be a possible cause for the guide wire breaking, the actual cause could not be 100% clarified due to the missing remaining guide wire.Based on the information available, it has been determined that no corrective and preventative action is proposed.
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