This report is being resubmitted for an incident that occurred earlier.Investigation found that during the initial surgery, the screw drive feature stripped during insertion into the l5-s1 level for a pars fracture repair.The surgeon was unable to remove the screw and it was advanced fully into the bone using grips/tools along the outside of the screw head.Imaging taken approximately three months post-operative, showed the screw had backed out about 13mm of its length.Evaluation of the returned screw found no apparent damage on the threaded or smooth portions of the screw shank.The hex drive feature has been stripped and there are scratches and marks along the head of the screw.The drive feature stripping is indicalfve of excessive insertion forces.It's possible that advancing the screw using vice grips affected the efficacy of the bone screw threads at full depth as non-axial rotation may h,we expanded the hole the screw created and allowed the screw to back out.However, the exact cause of the reported issue could not be determined.
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