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The two additional polyaxial screw reported are of the same product part number/description, but contain separate manufacturing lot numbers.676395 manufactured 6/17/2014; 671596 manufactured 3/11/2014.A review of the device history records revealed no manufacturing, processing or design related irregularities.The implants were found to be properly manufactured and released according to design specifications.No irregularities have been identified.Visual inspection found that all three (3) screws fractured and broke mid-way of the threaded shaft.It may be possible because revision surgery to remove and replace the screws took place approximately 5 months after initial implantation, a successful fusion/healing may not have begun to occur.In this case, the construct was more than likely carrying the majority of the load throughout the time of implantation with no gradual transfer of load that would be associated with fusion/healing.Typically, a functional fusion should take 3 - 6 months, but may take up to a year.During that time as successful fusion/healing occurs, there's a gradual transfer of load reducing the amount of stress placed on the implants.These implants are intended for temporary stabilization until fusion occurs they do not have an indefinite life and may fail over time if fusion is not achieved.The supplied instructions for use (ins-012) provide a warning to aid in reducing this type of event.
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