The returned everest closed polyaxial screw was visually inspected.The tulip and anvil components were confirmed to be disengaged from the main body of the screw assembly.The ball of the screw shank head was observed to have material deformation.The deformations appeared in a ring formation around the circumference of the ball head.The pattern observed indicates that the tulip may have been seated at an extreme angle.The inferior surface of the anvil component appeared to have witness marks from the ball head.It is unknown which returned tulip head was assembled and implanted with the subject screw.One of the tulip heads was returned assembled with the rod, which was unable to be removed during inspection.The wedged condition of the tulip and the rod indicates that the rod may not have been fully seated within the screw head.The inferior surfaces of both tulip heads were observed to have material deformation.The damage to the tulip heads was focused around the edges of the inner diameter, indicating interference of the screw shank from over-angulation of the head positioning.Complaint history records were reviewed for this catalog number, no adverse trends were observed.An x-ray was provided of the patient's construct in which the reported failure was confirmed.However, additional information was not received regarding the patient's bone quality, post-operative activity levels, or when the issue was noticed.The tulip of an implanted screw assembly can dislodge due to external trauma (e.G., fall), over-angulation of the implant and/or construct, extreme rod curvature, as well as other possible contributing factors.Therefore, a conclusive root cause cannot be determined at this time.
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