Radiographs received confirmed the event.Returned devices were dimensionally measured and found to be in specification.Torque handle was tested and was in specification.Subject device was visually evaluated and marring of the bottom of the set screw that was in contact with the rod, suggests loosening and instability.Final tightening of the lock screw cannot be confirmed from the markings on the bottom of the set screw.Unknown factors include: patient activity at the time or prior to the event, patient bone quality, the degree of spinal instability or patient compliance with post-operative care instructions or if the patient sustained a fall/impact of any sort (no trauma was reported).Root cause is unknown.
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