It was reported that the procedure was completed and components were submitted in place.The physician noticed a large gap in the lateral compartment of the knee.He had concerns that the unit may have maligned the femur, and wanted review of the device.The computer was taken off the field and it read, "navigation unit error, replace with new nav.Unit, return this unit.Stuck key 4.".
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The navigation log was available for review.The first session showed the nav was paired with rs s/n (b)(6) and the tka procedure was completed.Upon pairing with the returned nav unit, the rs s/n (b)(6) showed a use count of 121.Registration was completed with the femur offset angle and resection angle found to be within tolerance.During tibial registration, the error message "tibia - mount side switching warning" appeared, which means the rs was removed from the intrument and placed on the opposite side.Shortly after the warning, communication was lost with the rs, and the nav was powered down.The angle of flexion is measured by the reference sensor, and this data is communicated to the nav unit.It is suspected that the reference sensor s/n (b)(6) , which was found in the navigational log, may have experienced age-related gyro bias due to its high use count.The rs was not returned for investigation.No fault could be found with the returned navigation unit.The navigation unit powered up and successfully passed horizontal, vertical, and side calibration.The unit also successfully completed multiple simulated maneuvers during testing.The navigation unit was found to function as design.A review of the device history record (dhr) was conducted.The device passed all manufacturing specifications prior to release.
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