No device was returned to nuvasive for evaluation; the reported event was confirmed by review of a lateral radiograph showing the disengaged lock screw.Additionally, two (2) photographs of the explanted lock screw were provided.Review of the photographs identified severe damage to the threadform, including fracture of the thread in multiple locations, consistent with forced expulsion of the lock screw component.Only one side of the threadform and the top of the lock screw were visible in the images and as a result, damage to the inferior side and/or circumferential damage could not be evaluated using the images provided.A review of the device history record was performed and no discrepancies relevant to the reported event were found.Operative notes were not provided for review of usage/technique; further, no torque handle information was provided and it is unknown if the surgeon utilized hand tightening.A definitive root cause was unable to be determined with the information provided; however, the event may have resulted from incomplete rod reduction/normalization, incomplete tightening, and/or excessive post-operative loading.Labeling review: ".Potential adverse events and complications: potential risks identified with the use of this system, which may require additional surgery, include: bending, fracture or loosening of implant component(s), loss of fixation.".".Warnings, cautions and precautions: all lock screws should be final-tightened with the counter-torque and torque t-handle.Do not final-tighten through compression instruments (e.G.C/d rack and figure 8 compressor) in the set, as the rod may not be able to normalize to the tulip.Be cautious not to over compress or distract as you can loosen the screws in the spine and potentially pull out the screw.Care should be taken to insure that all components are ideally fixated prior to closure.".".Patient education: preoperative instructions to the patient are essential.The patient should be made aware of the limitations of the implant and potential risks of the surgery.The patient should be instructed to limit postoperative activity, as this will reduce the risk of bent, broken or loose implant components.The patient must be made aware that implant components may bend, break or loosen even though restrictions in activity are followed.".".Post-operative warnings: during the postoperative phase it is of particular importance that the physician keeps the patient well informed of all procedures and treatments.Damage to the weight-bearing structures can give rise to loosening of the components, dislocation and migration, as well as to other complications.To ensure the earliest possible detection of such catalysts of device dysfunction, the devices must be checked periodically postoperatively, using appropriate radiographic techniques.".If any further information is obtained that would change or alter any information provided, a supplemental report will be filed accordingly.
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It was reported that the patient underwent an initial one (1) level posterior fixation procedure from l5 to s1.Subsequently, during a routine examination on an unknown date, the l5 lock screw was found to be dislodged from the tulip on a radiograph.The patient reported no pain or other symptoms.A revision procedure was performed approximately two (2) weeks later to replace the dislodged lock screw and retighten the other three lock screws.Information regarding the patient's post-op activity levels and if any trauma occurred was requested but not available.No further patient impact was reported.No additional information was available.
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