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This follow-up report is being filled to relay additional information, which was unknown at the time of initial medwatch.New information received: x-rays received, pictures of products received, lab test results received, letter from hospital received, revision report received.Corrected and additional information is filled in the follwing fields: investigation of this incident is currently ongoing, a follow up report will be submitted when additional information becomes available zimmer biomet (winterthur) will proceed with the investigation.An additional report will be submitted as soon as the investigation results are available.Zimmer biomet¿s reference number of this file is (b)(4).The following reports are associated with this event: 0009613350-2021-00184-1, 0009613350-2021-00186-1.
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Event description: it was reported that the patient had increased pain on the left hip side.Ct measurement showed 22 deg anterversion of the stem and an anterversion of 39 deg of the cup.Therefore, patient underwent a revision surgery.Review of received data: due diligence: no further due diligence required as all required information to support the conclusion is available or was already requested.X-rays: only x-rays concerning the left hip were evaluated.As there are no obvious changes over time in vivo, only some x-rays were selected to be in the report (see below).Additionally, two selected images of a mri and a ct are at hand that were not evaluated.(b)(6) 2001, (b)(6) 2001, (b)(6) 2001 - all x-rays show the situation before the implantation of the total hip endoprosthesis in the left hip.(b)(6) 2001 - a cementless total hip endoprosthesis is implanted on the left side.The inclination angle of the cup was measured and amounts to approximately 40°.The cup seems to be more anteverted than described in the surgical technique on page 9: the cup should be inclined at 40 to 45° and anteverted by 10 to 15°.Above the acetabular roof a bone fragment is fixed by a screw.(b)(6) 2001 and (b)(6) 2001 - compared to the previous study date there are no obvious changes.(b)(6) 2002 - compared to the previous study date there are no obvious changes.Incipient periarticular ossifications above the greater trochanter can be recognized.(b)(6) 2006 - compared to the previous study date there are no obvious changes.(b)(6) 2011 - compared to the previous study date there are no obvious changes in pelvic overview.Due to the different projection the second view cannot be compared to the previous one.In the second view it seems that there is a tiny notch on the posterior side of the stem¿s neck.(b)(6) 2012 - compared to the previous study date there are no obvious changes in pelvic overview.(b)(6) 2012 - compared to the previous study date there are no obvious changes concerning the left side in the pelvic overview and on the right side a cementless hip endoprosthesis is now implanted.(b)(6) 2012 - compared to the previous study date there are no obvious changes concerning the left side in the pelvic overview.(b)(6) 2013 - compared to the previous study date there are no obvious changes concerning the left side in pelvic overview.Comparing the second view to the one taken on 22 aug 2011 the tiny notch on the posterior side of the stem¿s neck seems to be more clearly visible.However, due to the different projection direct comparison is not possible.(b)(6) 2017 - compared to the previous study date there are no obvious changes.The tiny notch on the posterior side of the stem¿s neck is clearly visible and seems to be slightly deeper.(b)(6) 2020 - compared to the previous study date there are no obvious changes.(b)(6) 2021 - compared to the previous study date there are no obvious changes.Due to the different projection the second view cannot be directly compared to the previous one.0(b)(6) 2021 - situation after the revision surgery on the left side with change of cup and head.The tiny notch on the posterior side of the stem¿s neck is clearly recognizable.(b)(6) 2021 and (b)(6) 2021 - compared to the previous study date there are no obvious changes.Letter from the surgeon dated (b)(6) 2020: the patient received a total hip endoprosthesis on the left side consisting of a fitek cup combined with metasul insert, metasul head and an alloclassic stem on (b)(6) 2001 in the (b)(6).Until beginning of 2017 the patient was asymptomatic and there was a good course.Since (b)(6) 2017 the patient complained about pain lateral to the hip respectively gluteal.At that time this was considered as a tendinopathy of the abductors due to the surgical approach and treated with physiotherapy.Only 3 years later and at progressing complaints the posterior impingement of the components had been identified as cause.A blood test taken on (b)(6) 2020 to determine metal ion levels in blood (whole blood) gave the following: titanium not measureable, chromium 1.4 g/l and cobalt 1.88 g/l.A periprosthetic tumor due to wear particles could not be detected by mri.The antetorsion of the stem amounted to 22° and the anteversion of the cup in the inclination plane was about 39° measured on ct images.Therefore, a revision including a change of cup and head was performed on (b)(6) 2021.Lab report: date of receipt (b)(6) 2020, date of sample taking (b)(6) 2020 results: cobalt 32 nmol/l (reference < 66 nmol/l); chromium 27 nmol/l (reference < 75 nmol/l).Surgical report of revision, on (b)(6) 2021: diagnosis: initial wear particle reaction and symptomatic posterior component impingement due to abnormal high anteversion of the cup after implantation of a total hip prosthesis (transgluteal with metal-on-metal pairing) left in 2001 due to symptomatic coxarthrosis at residual dysplasia.Indication: three years ago the pain started and was always progressive.The posterior component impingement resulted in a notch on the neck of the prosthesis.The notch, however, is not considered as critical concerning high risk, as it is located on the pressure side and is still relatively small.The levels of cobalt and chromium in blood are, however, still in the normal range.In this situation, the cup and stem can only be changed via an anterior approach.Technical procedure: anterior capsulectomy is performed.The capsule is approximately 15 mm thick.The synovial membrane is only few millimeters in thickness but shows a clear metallosis.Samples for microbiological and histopathological examination are taken at different locations.The capsulectomy is completed until the prosthesis can be dislocated in external rotation.Subsequently, the posterior joint capsule is also resected.The acetabulum is exposed.The cup is cut using spherical chisels until it is released from the acetabulum.The anterior wall can be preserved.However, the posterior wall suffers from a partial substance defect but the acetabulum is not fractured.Several attempts are made to implant an allofit cup.Finally, after reaming to size 52 a trial size 54 can be anchored in the soft bone.An allofit cup 54/jj with 40 ¿ 45° inclination and 15 to 20° anteversion is impacted.There is a good primary fixation.A durasul insert jj/36 is placed.Fluoroscopy check is performed.The cup is in a more medial and cranial position than planned.The head is removed from the stem.The taper shows some corrosion but only a small surface is affected and the machining marks are still visible.After trial reduction with a l head showing a correct implant position finally a biolox option head size 36/l is placed.Histological report, input (b)(6) 2021, output (b)(6) 2021: diagnosis: resected part of the joint capsule (left hip) with low macrophage proliferation near the joint with pronounced phagocytosis of fine granular blackish, non-birefringent micro-particular wear (metal wear, corresponding to the macroscopic metallosis), micro-particular needle-shaped birefringent wear (polyethylene wear) and perivascular lymphocytic inflammation, no granulocytic inflammation.Comment: the perivascular lymphocytic inflammation is, within the bounds of an immunologic allergenic reaction, attributed to the metal wear.Product evaluation: visual examination: in the as-received state the polyethylene liner of the metasul alpha insert was still mounted in the fitmore shell.On the articulation side a smearing on the rim of the metasul inlay of about 10 mm in length and a sickle-shaped worn area on the adjacent polyethylene liner can be observed.Those are located opposite the shell¿s stabilization fins and close to the notch in the rim of the shell.On the rim of the polyethylene liner several small whitish zones pointing to subsurface cracks can be recognized.In these zones scratches and nicks can be noticed on the rim of the shell.On the anchoring side of the shell bone ingrowth can be seen.The pole pin of the insert appears slightly deformed and there are some slight grooves on one side.Further, it seems that there is a tiny whitish zone on the face surface of the pole pin.For further evaluation the liner was removed from the shell by knocking it out using the pole hole whereby the insert¿s pole pin was compressed and cracks in the material occurred.A layer of organic material was found on the inside of the shell and removed during the subsequent cleaning process.On the inner side of the fitmore shell some scratches can be seen.In the area between the anchoring of the stabilization fin and the antirotational spike the surface appears slightly lighter under certain lighting conditions.Closer inspection with a low power microscope revealed polished lines and dots in this area.The polyethylene liner of the metasul alpha insert shows some yellowish discoloration which seems to be more pronounced in the loaded area of the anchoring side.The latter is recognizable by a clear round imprint resulting from the anchoring area of one of the shell¿s fins as well as the shells marking below this area.Further, some backside changes can be noticed in the loaded area.On the majority of the anchoring surface the machining marks are still visible.The appearance of the indents deriving from the antirotational spikes of the shell indicates two slightly displaced spike incisions.Around one indent a partial circumferential zone with backside changes can be seen.On the articulation side the already above mentioned smearing on the rim of the metasul inlay can be recognized.The smearing also covers the outside of the inlay that was freed due to the wear of the polyethylene liner.The freed height of the inlay seems to be less than 0.5 mm.Numerous fine and some coarse scratches as well as slight metal smearings can be seen on the articulation surface of the metasul inlay.Closer inspection with the low power microscope revealed a possible borderline between the loaded and unloaded area on the spherical calotte close to the bevel of the inlay.The appearance of the bevel itself does not point to a rim loading situation on the entire circumference of the inlay.Obvious subsidence / tilting of the metasul inlay in the polyethylene liner cannot be observed.On the articulation surface of the metasul head some coarse damage/scratches as well as fine scratches are visible.The articulation surface was inspected under the microscope at 200-times magnification with differential interference contrast (dic).In the loaded area of the surface fine scratches are visible and the carbides, which protruded slightly in the original surface state, are levelled.In the unloaded area the original surface state with slightly protruding carbides is recognizable.Between the two areas there seems to be partially a transition zone and partially a borderline.The head taper shows surface changes due to fretting corrosion on the entire contact area with the stem taper.Wear measurement: the wear measurement was carried out.The total linear wear value is 10.7 m for the head which results in an annual wear rate of 0.5 m.The wear map of the insert did not show a clear wear zone.Therefore, it is not possible to determine a wear value.However, the measured diameter of the insert is still within the manufacturing tolerances.For a metasul-pairing with diameter 28 or 32 mm retrieved within the first year an average wear of 27.8 m / year per pairing was found.Retrievals explanted after two and more years in-vivo had an average wear rate of 6.2 m / year per pairing.Review of product documentation: device purpose: all involved devices are intended for treatment.Product compatibility: the product combination was approved by zimmer biomet.Dhr review: review of the device history records identified no deviations or anomalies during manufacturing.Conclusion: due tostomatic coxarthrosis at residual dysplasia the patient received a total hip endoprosthesis on the left side consisting of a fitek cup combined with metasul insert, metasul head and an alloclassic stem in (b)(6) 2001.There was a good course and the patient was asymptomatic until beginning of 2017.Since then the patient complained about pain which was always progressing.After initial treatment with physiotherapy a revision surgery was performed in (b)(6) 2021.As cause for the patient¿s pain a posterior impingement of the components had been identified.During surgery the cup was revised and the head changed.The x-ray evaluation shows that over the entire time in vivo between 2001 and 2021 neither obvious changes in the position of the implants nor in the surrounding bone occurred.However, the cup was implanted with an inclination of about 40° measured on the x-ray provided and an anteversion of about 39° measured by the surgeon on ct images.On the second view x-rays a possible notch on the posterior side of the stem¿s neck could be detected for the first time on the x-ray dated (b)(6) 2011.In the further x-ray follow-up, the notch becomes more clearly visible and appears to be slightly deeper than in 2011.The investigation of the retrieved components revealed the following.The anchoring side of the fitmore (formerly fitek) shell shows bone ingrowth.In the loaded area on the inner side of the shell an area with polished lines and dots can be seen.This matches with a corresponding area of backside changes on the anchoring side of the metasul alpha insert.Both observations indicated some very slight micromotion between the two parts.The imprints from the shell¿s contour in the polyethylene are distinct and on the majority of the anchoring surface the machining marks are still visible.The pole pin of the insert exhibits some grooves that were already visible before the disassembly.On the anchoring side of the insert the indents from the antirotational spikes indicate two slightly displaced spike incisions.Based on the above, the latter can be ascribed to manipulations performed during implantation and not to a rotational movement of the insert in the shell during time in vivo.The yellowing of the polyethylene liner of the insert can be attributed to the absorption and possibly diffusion of organic substances from the synovial fluid.The areas with subsurface cracks on the rim of the polyethylene liner are located where mechanical damage can be seen.Therefore, it can be assumed that the cracks only became obvious because of an applied mechanical force by manipulations most probably performed during revision surgery.The smearing on the rim of the metasul inlay and the sickle-shaped worn area on the adjacent polyethylene liner point to an impingement with the stem¿s neck which is confirmed by the findings of the x-ray evaluation.Due to the impingement, wear on the stem¿s neck and the polyethylene liner of the inlay occurred.Apart from this the articulation surfaces of the metasul components are inconspicuous.There are no indications for rim loading or other phenomena that in general could lead to increased wear.The wear value measured for the head is low compared to the annual average wear rate for a pairing given in.A wear value for the insert could not be determined due to the lack of a clear wear zone.However, the measured diameter of the insert is still within the manufacturing tolerances.On the head taper of the metasul head, surface changes due to fretting corrosion were observed on the entire contact area with the stem taper.The reason for the surface changes remains unknown.The co and cr values measured in the patient¿s blood before revision surgery are within the reference values provided in the lab report.Further, in the mri a periprosthetic tumor due to wear particles could not be detected.The metallosis found in the synovial membrane during revision surgery derived most probably from the impingement.The histological examination revealed metal wear, corresponding to the macroscopic metallosis, as well as polyethylene wear.Based on the retrieval analysis the impingement can be identified as the main source for the latter.Additionally, perivascular lymphocytic inflammation was observed and, within the bounds of an immunologic allergenic reaction, attributed to metal wear.It is assumed that the surface changes on the head taper of the metasul head may be a contributing factor to the lymphocytic inflammation.In summary, it can be concluded that due to the implantation of the cup with a too high anteversion an impingement of the stem¿s neck on the rim of the metasul inlay occurred.This situation seems to have led to the patient¿s complaints which, however, started only about 16 years after implantation.Based on the investigation the reported event can be confirmed.The quality records show that all specified characteristics have met the specifications valid at the time of production.Therefore, the investigation did not identify a nonconformance or a complaint out of box (coob).Based on the given information and the results of the investigation, we identified the root cause to be the implantation of the cup with a too high anteversion leading to an impingement of the stem¿s neck on the rim of the metasul inlay.The need for corrective measures is not indicated and zimmer switzerland manufacturing gmbh considers this case as closed.Zimmer biomet¿s reference number of this file is (b)(4).
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