The customer reported event was confirmed via correspondence with the field representative.The screw was discarded at the hospital and is unavailable for evaluation.Manufacturing record review and complaint history review could not be performed as the lot number is unknown.It was reported that the patient's bone quality was average, no x-rays are available, the gauthier torque wrench was used with the xia 3 anti-torque tube and tightened to 12nm.The screw hole was prepared with a probe and 5.5 mm tap.The rod was fully reduced.It was reported that the surgeon does not apply excessive force but did have trouble seating the xia 3 anti-torque tube onto the screw.The surgeon reportedly "buries the screws into the bone." as the device was not returned, a definite root cause cannot be determined.Possible root causes include burying the screw head into the bone, as this impedes the polyaxialty of the screw causing more stress to be onto the bone and/or the screw which may, in turn, cause the bone or the screw to break if enough force is applied.Additionally, the surgeon's struggles with the anti-torque tube may have contributed as this may have caused off-cantilever force to be applied to the screw during final tightening, which may have caused the bone to fracture.Device discarded.
|