Country of complaint: (b)(6).Post operative breakage of screw heads.Primary surgery; (b)(6) 2013 revision surgery: (b)(6) 2015 patient data: (b)(6), male, no light perception, person requiring dialysis; activity level : low (visually impaired , hemodialysis) -case description: (b)(6) 2013 : anterior cervical fixation to c3/4/5.(b)(6) 2013 : 6 months post-operative check-up.No problem.(b)(6) 2014 : x-ray exam revealed loosening of screws.(b)(6) 2015 : screw removal procedure was done.-intra-operative findings of the revision surgery: three screws were found to have loosened.All the locking pins and springs of the broken screws were recovered from the operative field; however, not all the petals that broke apart were recovered.C4/5 - non union.Components involved include: fj934t / abc self-locking cervical screw 4.0x18mm lot number 51894387 quantity: 2 (medwatch 3005673311-2015-00128); fj934t / abc self-locking cervical screw 4.0x18mm lot number 51871871 quantity: 2 (medwatch 3005673311-2015-00129).Component in use: fj758t / abc cervical plate 6 hole ta 37mm lot number 51865491.
|
Investigation: the components have been examined visually and microscopically with a keyence vhx-5000 digital camera and a panasonic dmc tz8 digital camera.We made a visual inspection of the screws and cervical plate.Broken petals, strong wear, and abrasions wear found on all of the involved screws.The abc cervical plate had strong abrasion around the slot holes.Batch history review: the device quality and manufacturing history records have been checked for all the lot numbers and found to be according to the specification, valid at the time of production.No similar incidents have been filed with products from these batches.Conclusion and root cause: the root cause of the problem is most probably usage and patient related.Rational: according to the quality standard and dhr files a material defect and production error can be excluded.No pores, inclusions or foreign bodies could be found on the point of rupture.The wear marks on the screw are clear indications of relative movement between screw and plate.This can go so far that the edge of the slot hole on the plate can abrade single petals.If single petals seize up, it can come to a backing out of the screw or loosening of the petals (tearing away).No capa is necessary.
|