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The reported event could be confirmed since the device was returned for evaluation and matches the alleged failure.The nail was completely fractured at the thinned webs of the proximal drill hole for the lag screw.The fracture pattern indicates fatigue failure, as evidenced by the presence of rest lines at the proximal section and the absence of plastic deformation.Slight deformation is observed at the medial end of the proximal section, likely caused by weight-bearing through the lag screw.At the distal end, significant damage is visible on the lateral side, which may have resulted from load-bearing stresses as well as explantation of the device.Based on the observations, the fatigue fracture appears to have originated on the lateral side of the anterior portion of the lag screw hole.Additionally, signs of a secondary sudden brittle fracture are present on the posterior side of the device.Evidence of misdrilling is visible on the posterior side of the nail, both inside and outside the lag screw hole.The shiny area on the nail¿s exterior surface, caused by friction, suggests an initial unsuccessful attempt to insert the lag screw, during which the screw was misaligned with the nail.This misaligned drilling and lag screw insertion created a chamfer-like edge on the lateral posterior side of the hole, weakening the construct.It must be noted, however, that the fatigue fracture was the primary cause of implant failure, while misdrilling most likely accelerated the breakage of an already weakened nail.The returned locking screw was also visually inspected and found broken at the midpoint.The threads of the screw are completely flattened, indicating that the screw rubbed against the nail walls, causing subsequent damage.The breakage appears to be a combination of fatigue failure from prolonged loading and a sudden brittle fracture due to the abrupt load transfer following nail breakage.On the available document, a formal medical opinion was sought: this is a non-union, as there is hardly any callus formation, which should be there after 6 months.Continuous movement in the fracture caused the failure of the nail and the screw.A review of the device history for the reported lot did not indicate any abnormalities.No corrective actions are required at this time.A review of the labeling did not indicate any abnormalities.No indications of material, manufacturing or design related problems were found during the investigation.Based on the investigation, the breakage of the implant happened in a fatigue manner by application of continuous high load over time.The exact root cause cannot be defined as non-unions are, in general, multifactorial.The location and pattern of the fracture, biology, and the technical aspects of the surgical procedure have contributed to the event.Furthermore, patient activity levels post-op may also have contributed to an inadequate load distribution and, therefore, the breakage of the implants.If more information is provided, the case will be reassessed.
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