(b)(4).Investigation: a visual inspection of the femur cutting guide (ns334r) threaded pin (np583r) was made.Visible helix traces and visible damaged tips were detected.Also grooves in the borehole was found.Examination of the boreholes was made with a control gauge and it was determined that they and not complying with the initial manufacturing status.The boreholes no longer have the initial diameter through material throw-up and using traces.Batch history review: ns334r: the device quality and manufacturing history records have been checked for the lot number (4508169308) and found to be according to the specification, valid at the time of production.Three similar incidents have been filed with a product from the batch (4508169308).Conclusion and root cause: the root cause of the problem is most probably usage related.Rationale: investigations lead to the assumption that the grooves in the boreholes, quicks and grooves were caused by a usage error due to a material throw-up of the pin.The boreholes no longer have the initial diameter through material throw-up and using traces.The quirks and visible helix traces may have been caused by the material throw-up and the additional movement through using the pin.Particles or forces applied during corrections while navigating may have led to a material throw-up.There is a possibility for pre-damage or similar due to previous surgeries.If the instruments are in such poor condition they should no longer be used.Due to a material throw-up and grooves in the boreholes, there is the possibility that the pin and the inner surface of the hole could have been cold welded.The cold welded is the cause for the deformed shaft.We cannot determine the exact cause for the visible damaged tip.According to the instructions for use (ifu) the following points and warnings much be observed: excerpt from ifu: prior to each use, inspect the product for loose, bent, broken, cracked, worn, or fractured components do not use the product if it is damaged or defective.Set aside the product if it is damaged.Replace any damaged components immediately with original spare parts.A capa was initiated.Associated medwatch: 9610612-2019-00077; 9610612-2019-00078.
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