ZIMMER GMBH ZNN, CMN LAG SCREW¸ 10.5 MM, 100 MM, INCLUDING SET SCREW; ZIMMER NATURAL NAIL SYSTEM CEPHALOMEDULLARY NAILS
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Model Number N/A |
Device Problem
Device Damaged by Another Device (2915)
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Patient Problem
No Consequences Or Impact To Patient (2199)
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Event Date 09/12/2018 |
Event Type
malfunction
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Manufacturer Narrative
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Concomitant medical products and therapy date detail of product: item number 47249321110, item name z nail cpm 10mmx21.5cm 125 l, lot # 2623750.The manufacturer did not receive x-rays but received other source documents for review.The manufacturer did not receive the device for investigation.The device history records were reviewed and found to be conforming.Additional information has been requested and is currently not available.Notes: the implantation and explantation dates are left empty as the device involved in this complaint is an instrument.Hence, no expiration date is captured, for the same reason.A cause for this specific event cannot be ascertained from the information provided.As soon as supplemental information becomes available, an updated report will be submitted.(b)(4).
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Event Description
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It was reported that during explantation while the lag screws were removed, the attachment where the screwdriver is set on was damaged.To complete the procedure the same instrument was used with more force to remove the lag screw.
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Event Description
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Investigation results are now available.
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Manufacturer Narrative
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Dhr-review: ref#: 47-2495-100-10 lot#: 2944743 - yield: 90.- delivered: 88.- scrapped: 2.- reason for scrapped: scrapped due to welding marks on the surface.The device manufacturing quality records indicate that the released components met all requirements to perform as intended.Ref#: 47-2493-211-10 lot#: 2623750 - yield: 30 - delivered: 25 - scrapped: 5 - reason for scrapped: scratches on the surface the device manufacturing quality records indicate that the released components met all requirements to perform as intended.Trend analysis: no trend considering the following event is identified: lag screw breakage event description: the incident occurred during explantation.The lag screw notches were broken during the removing process.To complete the procedure the same instrument was used with more force to remove the lag screw.Devices analysis: - visual examination: the nail, lag screw, cortical screw and a set screw were returned for investigation.The visual examination shows that the lag screw notches were completely broken.The broken two pieces were not returned for investigation.The location of the broken pieces is unknown.In addition it can be seen that some damages and scratches on the outer surface of the lag screw shaft.The set screw shows a tip deformation.No relevant damages on the cortical screw.Review of product documentation: all involved devices are intended for treatment.- surgical technique: the removal of the lag screw is described in the zimmer natural nail system ¿ cephalomedullary standard surgical technique."to remove the lag screw it is not necessary that the set screw is completely removed.Turn the set screw two turns backwards and make sure that the set screw is still engaged in the threads of the nail.It is recommended to use the lag screw cannula as guidance for the lag screw inserter while removing the lag screw.Assemble the lag screw inserter through the lag screw cannula into the lag screw.Use the compression device to push the lag screw cannula to the bone.Make sure the lag screw inserter is fully seated.Hand tighten the lag screw inserter with the 3.5mm hex screwdriver.If a secondary option is needed to remove the lag screw, the cm lag screw extraction device ref 00-2490-090-12 can be used.To use the cm lag screw extraction device, align its axis with the axis of the cm lag screw that is being explanted.The conical thread of the cm lag screw extraction device should then be engaged and rotated in a counter-clockwise motion into the exposed lateral threads of the cm lag screw that is being explanted.The rotation direction is counter-clockwise as the cm lag screw extraction device utilizes reverse-cutting flutes to enable mating to the cm lag screw.While rotating, a constant axial force must be applied to maintain the tool driving into the cm lag screw thread.While continuing to rotate the cm lag screw extraction device counter-clockwise, the cm lag screw that is being explanted will unseat from the bone and can be removed".- review of biocompatibility specification.In accordance with iso 10993-1 (2009) the zimmer natural nail system - cephalomedullary nail (cmn) is categorized as "implantable devices" with "tissue/bone" contact for more than 30 days (c - permanent).Biocompatibility evaluation aims to assure that the implanted device does not induce any kind of unexpected body reaction during the life time of the implant.For the biocompatibility evaluation of the zimmer natural nail system - cephalomedullary nail (cmn) we followed the guidelines of the iso 10993-1.Conclusion summary: it was reported that the notches of the lag screw broke off during removal of the znn system.The explanted devices were returned for investigation.The brekage of the lag screw notches can be confirmed.The broken pieces were not returned.The correct removal of the lag screw is described in the zimmer natural nail system ¿ cephalomedullary standard surgical technique 97-2493-002-00.There are possible causes for the breakage of the lag screw tabs during the removal of the znn nailing system: ¿ if the contact surface of the instrument and implant is too small, too high forces will be transmitted on the cams which lead to a fracture of this section.¿ excessive bone ingrowth onto the lag screw due to long in vivo time of the implant system, which makes high forces needed to remove the screw in a removal case.The in vivo time is unknown.¿ pathogenic bone diseases (e.G.Bone tumor) which affect mechanical properties of the bone (harder/ denser bone substance).However, based on the given information and the results of the investigation, we were not able to identify a specific root cause for this issue.The need for corrective measures is not indicated and zimmer gmbh considers this case as closed.Zimmer biomet's reference number of this file is (b)(4).
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