Batch review performed on (b)(6) 2022: lot 1900729: (b)(4) items manufactured and released on (b)(6) 2019.Expiration date: 2024-04-22.No anomalies found related to the problem.To date, (b)(4) items of the same lot have been sold without any similar reported event in the period of review.Clinical evaluation performed by medical affairs director: few months after primary tkr with a constrained device, the patient feels apin and the radiographic analysis shows a loose screw in the joint.The patient is taken to surgery and the screw replaced with a new one.It is possible that the torque wrench had not been used in primary surgery: this may lead to insufficient torque being applied to tighten the screw, and in turn this is a possible cause for self-unscrewing of the fixation screws, which could be reproduced in the laboratory.No further clinical consequence is to be expected.Visual inspection performed by r&d knee manager: revision surgery of a gmk hinge tibial insert performed 3 months after the primary surgery because hinge post screw was found not loosened in the joint.The hinge post extension with its screw have been sent back to medacta for inspection.Tibial insert and its secure screw have not been sent back.The screw looks intact, with no signs of damage.It is still possible to completely engage the screw into the post extension.No other elements potentially relevant for the event can be noted on the returned parts.From visual inspection it is not possible to determine the root cause for this unlikely and undesired event. the usage of the torque limiting screwdriver, mandatory for this application, has not been confirmed.We can only suppose that the hinge screw was not properly secured or that the hinge post was not well connected to the femoral component before its fixation with the screw.One of these could had led the loosening of the screw in the joint; but there is no evidence in support of these hypothesis. reason for unscrewing remains unknown.From visual inspection there is no evidence that the event is related to a faulty device.
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