39yo male smoker that continued to smoke following original spinal fusion surgery on (b)(6) 2021 presented approximately two years post op after bending over and attempting to lift a heavy load.Two cosmolock 6.5 x 45mm screws located at s1 were identified as being broken.Patient believed he was alergic to the titanium used in the implants so revision surgery performed on (b)(6) 2023 to remove the broken screws.This is report one of two and covers one of the two broken screws.Both screws are of the same pn, size, and lot number.Screws were returned for the investigation.The screws were visually inspected.The inspection showed both screws appeared to have significant fatigue beach marks on the face of the break.One screw has approximately two thirds of the face containing beach marks, while the other screw has an even greater percentage.This shows that the screws were well fatigued prior to the ultimate breakage and most likely did not require much of a load to complete the break.The propagation of the fatigue stresses appear to be at the points on the screw shanks furthest from the construct (caudal) and in line with the rod slot.This position would be the typical location of fatigue propagation due to seeing the highest tensile stresses in a construct.Review of the device history records showed no nonconformities in the lot, that the devices were properly manufactured per the engineering requirements and material specifications using the appropriate certified materials.Trend analysis and historical data review show no other issues with any other devices from this lot of product.The user in this case did not utilize an interbody device for the fusion.This can lead to addtional stress loading on the construct over what is seen when the load is shared by an interbody device.The screws performed as intended and survived longer than the time for which they were validated to perform without issue.Most likely contributing causes to the failure were use of the system without employing an interbody device to share the load and the patient attempting to lift a heavy load.
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