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Concomitant medical products: metasul durom, component for acetabulum, uncemented, 56, 50, code p, item# 01.00214.056, lot# 2382483.Metasul large diameter hd 50/p.Item# 01.00181.500, lot# 2385673.Head adapter l/+4 12/14-18/20, item# 01.00185.147, lot# 2394080.Alloclassic offset stem 4, item# 01.00121.040, lot# 2402652.Event description: it was reported that the initial hip surgery (left) was performed on (b)(6) 2007 in the hospital of (b)(6).Due to osteolysis the patient had his revision surgery at the (b)(6) on (b)(6) 2019.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: for some dates second views of left and right hip were received.As this report concerns the left hip, only the second views of the left hip are assessed.X-rays taken after the revision of the left hip are not evaluated.(b)(6) 2018, pelvic overview: situation before revision, thps are implanted on both sides (durom cup, metasul ldh head, alloclassic stem).The equatorial fins of the cup are cranially not anchored in the bone.There is an osteophyte above this area.The inclination of the cup was measured and amounts to ca.44°.The anteversion seems to be rather low.Radiolucent gaps between the stem and the bone bordered by sclerotic lines can be seen and osteolytic areas are visible.(b)(6) 2018, pelvic overview and second view, left hip: there are no obvious changes in the pelvic overview compared to the previous one.Osteolytic areas are visible.(b)(6) 2019, pelvic overview: this x-ray was named (b)(6) 2018, however, as it is visible that on the right side a revision was performed, it should be (b)(6) 2019.Compared to the previous pelvic overview there are no obvious changes.(b)(6) 2019, ct images: several cross-sections from a ct scan were received in jpeg format which are not further evaluated.(b)(6) 2019, pelvic overview: there are no obvious changes compared to previous pelvic overview.(b)(6) 2019, pelvic overview: there are no obvious changes compared to previous pelvic overview.(b)(6) 2019, pelvic overview and second view, left hip: situation after revision surgery.Letter from the surgeon dated (b)(6) 2020: in his letter the surgeon states that the explants from the right hip of the same patient were already sent for analysis in 2019.The primary surgery was performed at orthopaedie (b)(6).The patient is ambitious in sports.Course: the patient seems to have never been completely free of symptoms since the implantation of the two hip prostheses in 2007.In 2016 external investigations were performed which describe an already known, extensive osteolysis in the femur on both sides.After revision of the right side on (b)(6) 2019 and good course the revision of the left side was performed on (b)(6) 2019.The cobalt value in blood has already recovered.Comment of the author: as this report concerns the explants of the left hip, only the reports for the latter are summarized in the following.Surgical report of implantation, (b)(6) 2007, klinik (b)(6): diagnosis: bilateral coxarthrosis, left more pronounced than right.Procedure: after exposure and opening of the capsule, the femoral head is dislocated.Osteotomy of the femoral head is performed.The acetabulum is prepared using rasps of increasing size until a trial cup of size 56 fits firmly.Osteophytes are removed and a durom cup size 56 is impacted.The latter is firmly seated in correct position.The femur is exposed and the femoral canal is opened.The femoral canal is prepared by successive rasping until the trial stem size 4 is firmly seated.The distance between the tip of the taper and the trochanter minor is measured and amounts to 50 mm.This corresponds exactly to the preoperative planning.A durom trial head with an adapter size l is placed and the hip is reduced.There are stable conditions, no dislocation tendency, good joint play and equal leg lengths.The trial components are removed and the definitive components an alloclassic stem size 4, 121° and a durom head, size 50, with an adapter size l are placed.The hip is reduced, redon drain is placed and the wound is closed.Surgical report of revision, (b)(6) 2019, (b)(6): diagnosis: pronounced granulomas on both hips due to wear.State after bilateral total hip replacement with posterior approach in (b)(6) 2007.Distinctive atrophy of the rectus femoris muscle on the right side (mr tomography on (b)(6) 2018).State after revision of right total hip prosthesis with transgluteal approach on (b)(6) 2019.Indication: five months after successful surgery of the right hip with very satisfied patient and halving of the increased chromium and cobalt levels in blood serum the indication for the revision of the left side is given.Procedure: a kocher-langenbeck approach is used.A pseudotumor is found in the area of the bursa trochanterica which is removed.The trochanter osteotomy is marked and then performed according to planning.The anteroventral capsule is exposed.The stem can be removed without problems.There is large osteolysis in the proximal femur which is debrided.Four samples are taken for bacteriological preservation and additionally one for histology.The acetabulum is exposed.Complete capsulectomy is performed.After cutting around the durom cup it can be removed without problems.But, a huge osteolysis anterosuperior with corresponding defect is seen.Long irrigation using jet lavage is performed.There is no significant bone loss.The further steps in the revision report describe the implantation of a versafit cc trio 64 cup, a highly crosslinked polyethylene insert g/36, a quadra-r 5 lat.Stem and a biolox delta 36/l head and the refixation of the trochanteric fragment.Histology report, input (b)(6) 2019, output (b)(6) 2019: questions from the clinic: large osteolysis at metal on metal pairing! wear? infection? material: capsule left hip.Diagnosis: tissue including fatty tissue and connective tissue rich of collagen fibers with local areas of fibrin deposits, low-grade to focal moderate-grade histiocytic reaction and local deposits of blackish fine-grained pigment corresponding to signs of metal wear and local deposits of hemosiderin.Blood test reports: results for samples taken on (b)(6) 2018.Chromium (blood) : 66.4 nmol/l (reference 15.0 - 75.0, < 135 (endoprosthesis)).Cobalt (blood) 232.3 nmol/l (reference 8.5 - 66.0, < 119 (endoprosthesis)).Results for samples taken on (b)(6) 2019.Chromium (whole blood) 34 nmol/l (reference < 75).Cobalt (whole blood)23 nmol/l (reference < 66).Product evaluation: on one halve the anchoring side of the durom cup is covered by bone while on the other halve only sparse attachments can be observed.This halve also includes an area of about 55 mm in length along the equator and 10 to 15 mm in width where the ti-vps coating is missing.In this area there are two whitish zones which could possibly be remains of bone however it could not be determined if those are just indented into or grown onto the rough surface.For comparison bone in the halve with sparse attachments is shown.On the articulation side of the cup numerous fine as well as some coarser scratches are visible.The latter are mainly located closer to the bevel.In one location, close to the bevel, an area with organic deposits can be observed.Opposite to this area an area that is rather free of scratches can be seen.Closer inspection of the articulation surface with a low power microscope revealed an approximately 25 mm long stripe of parallel scratches probably combined with smearing on the spherical calotte directly adjacent to cup¿s bevel.The metasul ldh head exhibits numerous fine scratches, some damage probably due to transport (all components received in one bag) and / or revision and an area with organic deposits close to the equator.The articulation surface of the metasul head was investigated under the microscope at 200-times magnification with differential interference contrast (dic).Scratches can be recognized in the loaded as well as unloaded area whereby the density of the scratches is lower in the unloaded area.In the loaded area the carbides, which protruded slightly in the original surface state, are levelled, while the carbides are still recognizable in the unloaded area.In the as-received state the metasul ldh head adapter was still fixed in the head taper.For further investigation the parts were disassembled using the adapter extractor.All taper surfaces were examined using a low power microscope.On the head taper a small zone with surface changes matching a similar zone on the outer head adapter was detected.On the inner surface of the head adapter surface changes due to fretting corrosion were found.Two marks can be observed in the proximal region of the contact area.Under certain light conditions it seems that there is a height difference between the marks and the surrounding surface with the marks being slightly higher.Revision damage in the form of scratches, instrument and drill marks is visible on the alloclassic sl offset stem.Remains of bone attachments can only be recognized in the distal third of the anchoring surface of the stem.On the posterior side of the stem an area with small shiny polished lines can be observed.Further, on the medial side of the stem circular shiny polished zones and small shiny polished lines are recognizable.The taper surface has a blackish appearance.In the proximal region there are two indented marks matching the ones visible on the inner surface of the head adapter.The stem taper was further investigated with a light microscope.Most of the thread grooves are filled with blackish deposits.An increasing width of the crests of the thread and decreasing width of the thread grooves can be seen compared to the taper structure of a pristine stem.This points to fretting on the stem taper.Wear measurement.The wear measurement of the articulation surfaces of the metasul head and the durom cup were carried out on a 3d measuring machine.The total linear wear value for the metasul head is 6.7 um which results in an annual wear rate of 0.56 um.The wear map of the durom cup shows no clear wear zone.Additionally, the visual appearance of the cup articulation surface rather points to a loaded area extending from one side via the center to the other side.The method to determine the wear requires the detection of a worn and an unworn area on the same parallel of measuring points.As this requirement is not met it is not possible to determine the wear value.However, the measured diameter of the cup 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 um / year per pairing was found.Retrievals explanted after two and more years in-vivo had an average wear rate of 6.2 um / 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: in (b)(6) 2007 the patient received bilateral total hip endoprostheses including durom cup, metasul ldh head, metasul ldh head adapter and alloclassic sl offset stem.The implantation surgeries were performed in klinik (b)(6).Since implantation the patient seems to have never been completely free of symptoms.In 2016 investigations were performed which describe an already known, extensive osteolysis in the femur on both sides.After revision of the right side in (b)(6) in (b)(6) 2019 and good course, the revision of the left side was performed on (b)(6) 2019 in the same hospital.Before revision of the right side the cobalt and chromium levels in the patient¿s blood were determined and at least for cobalt found to be elevated according to the reference given in the lab report.After revision of the left side the levels decreased and are within the reference range.During revision surgery of the left side the surgeon indicated that a pseudotumor was found in the area of the bursa trochanterica.Further, large osteolysis in the proximal femur was debrided and additionally osteolysis in the anterosuperior area of the acetabulum was discovered.On the x-rays at hand, taken in (b)(6) 2018, clear signs of osteolysis in the femur can be seen.In alignment to this, the explanted stem shows only remains of bone attachments in the distal third in combination with signs of loosening at least in the form of small polished lines.It is unknown if the circular shiny polished zones derived as well due to loosening.As the complete x-ray follow-up is not at hand the bony situation immediately after implantation and its development over time in vivo is not known.Therefore, it stays unknown at what point in time the osteolysis started to develop.The wear measurement resulted in a low wear value for the metasul ldh head.For the durom cup a clear wear zone could not be identified but the measured diameter is still within the manufacturing tolerances.The articulation surfaces of head and cup did not show conspicuous phenomena, e.G.Rim loading.Signs of fretting and marks were observed on the alloclassic stem taper.On the inner surface of the head adapter signs of fretting and corrosion as well as marks can be seen.On the head taper a small zone with surface changes matching a similar zone on the outer surface of the head adapter was observed.Concerning the marks in the current literature a similar phenomenon was described for a different bi-modular hip design of a different alloy composition.The conditions of mounting of the large diameter head with its head adapter on the stem taper, e.G.Impaction force, impaction angle, condition of the taper surfaces (dry, wet), are factors that influence the quality of the taper connection.Considering the results of the wear measurement, it can be assumed that the elevated cobalt level in the patient¿s blood derived probably from the surface changes observed on the taper surfaces of stem and head adapter.It should be considered that at the time of measurement the patient had still bilateral metal on metal prostheses.Amongst other things the histological report stated local deposits of blackish fine-grained pigment corresponding to signs of metal wear.It remains unknown if the surface changes of the taper surfaces could also be a source for these deposits.On the anchoring side of the durom cup a part of the ti-vps coating is missing.The investigation could not reveal a clear indication for either a separation between the coating and the cup before or during revision surgery.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 received information and the retrieval investigation it stays unknown if and to which extent any of the above mentioned findings could have contributed to the osteolysis around the stem and in the anterosuperior area of the acetabulum as well as the pseudotumor in the area of the bursa trochanterica as described in the revision report.In conclusion, as the cause may be multifactorial an exact root cause could not be identified for the reported event.The need for corrective measures is not indicated and zimmer (b)(4) manufacturing (b)(4) considers this case as closed.Zimmer biomet¿s reference number of this file is (b)(4).
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