(b)(4).Associated products: item reference:(b)(4), item name: oxf uni tib tray sz b rm pma, item lot:528620.Item reference:(b)(4), item name: oxf twin-peg cmntd fem md pma, item lot:494860.The device will not be returned for analysis; however, an investigation of the reported event is in progress.Once the investigation is completed, a supplemental medwatch 3500a will be submitted.
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(b)(4).This follow-up report is being submitted to relay additional and/or corrected information.The following sections were updated: b4, b5, g3, g6, h1, h2, h3, h6, h10.No product was returned or pictures provided; visual and dimensional evaluations could not be performed.A review of the device manufacturing records confirmed no abnormalities or deviations that could be related to the reported event.Device used for treatment.Medical records/radiographs were provided and reviewed by a radiologist: it was reported that a patient underwent an initial right knee arthroplasty on (b)(6) 2022.Subsequently, a revision procedure due to dislocation of mobile bearing was performed on (b)(6) 2023 (6 weeks later).It was further reported the patient had a bmi >41 and mcl insufficiency leading to bearing dislocation was noted.Four images within 2 sets of medial compartment unicompartmental arthroplasty of the right knee first set: immediate postoperative frontal and lateral views.Second set: frontal lateral views taken at some time after immediate postoperative study.Immediate postoperative images demonstrate normal appearance of the hardware without hardware abnormality or periprosthetic lucency.Punctate metallic density body in the medial portion of the medial compartment is likely related to the mobile bearing.There is slight narrowing of the lateral compartment with genu valgus alignment of the knee.The 2nd set of images demonstrate displacement of the above-mentioned mobile bearing now dislocated medial to the medial compartment with 2 punctate metallic density bodies seen medial to the joint space.There is resultant narrowing of the medial compartment.The lateral compartment now appears malaligned.Hardware otherwise unremarkable.On the initial immediate postoperative images there appears to be increased spacing of the medial compartment and reduced spacing in the lateral compartment with genu valgus.This could be related to the mobile bearing which is in the medial compartment and possibly causing abnormal spacing.Potentially, this could be related to the eventual displacement of the mobile bearing which is located medial to the medial compartment on the later time point imaged.A definitive root cause cannot be determined.If any further information is found which would change or alter any conclusions or information, a supplemental report will be filed accordingly.Zimmer biomet will continue to monitor for trends.
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