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This follow-up report is being submitted to relay corrected and additional information.Additional: h2, h6, d1, d4, d9, h3, h4.Correction: b4, g3, g6, h10.Event description: it was reported that the products were implanted in the right hip on (b)(6), 1996 and underwent revision on (b)(6), 2019 due to a bone fracture.During the revision both the cup and the stem were revised.The patient has bilateral hip replacements; had an implant surgery on the left side on (b)(6), 1999.Blood lab tests results showed cobalt of 16 and chrome 12.During the revision, it was observed that there were almost no signs of bone ongrowth to the cup, no bone integration, the cup was easily extracted.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.- letter from the surgeon dated (b)(6) 2020: the implantation was performed in kantonsspital münsterlingen.The patient has bilateral total hip endoprostheses.There were only early postoperative check-ups, however further check-ups were not performed for years.Due to a tripping fall the patient suffered a periprosthetic acetabular fracture on the right side.Until then she was free of complaints.The stem was revised because of the approach used.- lab report, date of receipt (b)(6) 2020: whole blood results: cobalt 16 nmol/l (reference < 66 nmol/l) chromium 12 nmol/l (reference < 75 nmol/l) - surgical report of implantation performed by dr (b)(6) at (b)(6) on (b)(6) 1996: diagnosis: protrusion coxarthrosis on the right side indication: progressing bilateral coxarthrosis, especially with pronounced protrusion coxarthrosis on the right side technical procedure: a lateral approach is used.The already much deepened acetabulum is reamed until size 64, the threaded shell is placed and shows firm seat.Cancellous bone is impacted in the bottom of the acetabulum.The metasul insert is impacted and firmly fitting.The femoral medullary canal is opened and reamed until firm fitting of size 5.In addition cancellous bone is impacted at the collar of the prosthesis.During trial reduction there is full tension so that a metasul head size s can be used.After definite reduction full tension is seen, the leg length is identical and there is no dislocation tendency.- surgical report of revision performed by dr (b)(6) at (b)(6) on (b)(6) 2019: diagnosis: multi-fragmentary periprosthetic fracture of the acetabulum (two column fracture) on the right side typ ucs b3 after implantation of an uncemented total hip arthroplasty (transgluteal with metal-on-metal pairing) on (b)(6) 1996 due to symptomatic coxarthrosis indication: the patient has bilateral total hip endoprostheses that have been implanted in the nineties.There has been no follow-up for a long time, but the patient was symptom-free.A periprosthetic fracture of the acetabulum occurred as a result of a tripping fall.The cup is unstable and will be pushed further and further into the small basin without load over the course of a few days.This is an additional danger to injure inner organs.The stem is changed for exposure reasons, as a transfemoral approach is chosen to be able to reconstruct the acetabulum.Surgery: revision of the hip prosthesis (transfemoral) on the right with plate osteosynthesis of the posterior acetabular column, acetabular defect filling with a trabecular metal augment, change of cup and stem (burch 50, palacos r+g, müller low profile cup durasul 54/36, biolox delta 36/s, revitan gerade 20x140+65 mm) and re-osteosynthesis of the proximal femur with cerclage wires and osteosutures.Technical procedure: debridement of the severely scarred trochanteric bursa is performed.The piriformis muscle is atrophic but can barely be identified.The anterior half of the gluteus medius is fatty, the origin shows a defect.Osteotomy is conducted from the greater trochanter until 140 mm distally to the tip of the trochanter.Anteriorly the cut is performed with chisels.There, the bone fractures as soon as the second chisel is used.Despite larger osteolyses, the stem is firmly fixed.After dislocation of the prosthesis, it can be removed retrograde without problems.There is almost no adherent bone on the surface.The cup is obviously loose and can be easily removed with the forceps.There is no evidence of bony integration on the cup.As expected, the anterior inferior iliac spine is fractured.The posterosuperior acetabular wall is a single fragment.The fragment of the ischium is identified.Appropriate osteosynthesis is performed.The roof of the acetabulum has a pronounced bone defect.Centrally, there is as well a defect.The central defect is filled with a trabecular metal acetabular augment.A burch-schneider-ring is adapted, inserted and fixed with screws.A müller flat profile cup durasul 54/36, with 40° to 45° inclination and approximately 20° anteversion is cemented.A protective cerclage wire is placed around the entrance of the femur.After preparation a straight revitan stem 20 x 140 mm is inserted and combined with a proximal part size 65 and a head 36s.Reduction of the bone fragments and osteosynthesis is performed.- x-rays: in the following table only the relevant x-rays are evaluated.The pictures of the ct-scan were not considered for evaluation.(b)(6) 2019, pelvic overview, right hip axial view: the cup has a low inclination angle and protrudes clearly into the small basin.Therefore the bony border of the acetabular roof cannot be identified.There is a conspicuous peri-implant radiolucent area at the lower rim of the cup.A fracture of the lower ramus pubis can be recognized.Several small brightened areas are noticeable at the level of the proximal femur in gruen-zones 6 and 7 close to the implant.In the axial view a larger radiolucent area bordered by a sclerotic line in gruen zones 8, 9 and 14 can be seen.(b)(6) 2019, 2x pelvic overview: compared to the previous x-ray the cup is further tipped so that it is in an almost horizontal position.At the lower rim of the cup the former bony border of the cup is more visible.(b)(6) 2019, pelvic overview, right hip axial view: situation after revision surgery on the right side.- patient data: (b)(6), female, born in 1927, 58 kg, 1.70 m, bmi 19.4 product evaluation: - visual examination in the as-received condition the metasul head and the alloclassic sl stem as well as alloclassic csf metasul insert and cup were still mounted.For easier handling and permitting also investigation of the taper and anchoring surfaces, respectively, all parts were disassembled during the examination.The alloclassic sl stem shows bone attachments on all anchoring surfaces whereas most proximally especially on the anterior side signs of bone ongrowth cannot be recognized by naked eye.Damage most probably due to the removal of the stem in the form of scratches and instrument marks are visible mainly in the most proximal area on the anterior side as well as on the posterior side.The stem taper is blackish discolored.In the proximal third it shows the four arrow-shaped marks deriving from the head taper.Closer inspection with the light microscope revealed that in those areas the stem taper¿s groove structure is slightly deformed.On the posterior side three overlaying marks can be seen which can probably be attributed to the disassembly.Further, it was observed that the taper¿s groove structure appears in some areas widened and is partially filled with deposits (sometimes blackish).In the most proximal area of the taper partially greenish- whitish deposits can be seen.On the taper of the eccentric metasul head the area that was in direct contact with the stem¿s taper is well recognizable and exhibits surface changes due to corrosion (taper entrance) and fretting corrosion (contact zone).In the most proximal area of the taper, where the four arrow-shaped marks serving as elements for rotational stability are located, greenish- whitish deposits could be detected by closer inspection with a binocular with a magnification up to 40x.On the articulation surface of the metasul head an almost complete borderline between the loaded and the unloaded area as well as a matt circular ring close to the pole are visible under certain lighting conditions.Further, a coarse scratch near the pole and some organic deposits adjacent to the borderline are present.The articulation surface was inspected under the microscope at 200-times magnification with differential interference contrast (dic).The borderline between both areas is well identifiable.The matt circular ring close to the pole is probably an organic deposit.In the loaded area numerous fine scratches are recognizable while in the unloaded area the original surface state with slightly protruding carbides can be found.The polyethylene liner of the alloclassic csf metasul insert shows some damage on the articulation side.There is no obvious change of the position (subsidence / tilting) of the metasul inlay in the liner.Numerous fine scratches can be seen on the articulation surface of the metasul inlay.Closer inspection with a low power microscope revealed a short small smearing on top of the rim of the inlay as well as an area likely with smearing on the spherical calotte adjacent to the bevel.Both smearings are located almost opposite to each other.The polyethylene liner of the insert appears to be partially slightly yellowish discolored on the anchoring side.There are no backside changes on the polyethylene.The metal back of the insert exhibits remains of bone ongrowth in one area.There is nothing to report about the inner side of the alloclassic csf shell.On its anchoring side bone attachments and some scratches are visible.- wear measurements: the wear measurement was carried out on a 3d measuring machine type cmm5, sip geneva.The total linear wear value is 19.7 m for the head which results in an annual wear rate of 0.8 m for the head.The wear map of the inlay does not show a really clear wear zone.Based on the visual examination it was decided to favor one possible zone.This has a total linear wear value of 10.8 m resulting in an annual wear rate of 0.5 m.The measured diameter of the inlay 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 [1].Retrievals explanted after two and more years in-vivo had an average wear rate of 6.2 m / year per pairing [1].Review of product documentation: - device purpose: all involved devices are intended for treatment.- product compatibility: the compatibility check was performed from www.Productcompatibility.Zimmer.Com and showed that the product combination was approved by zimmer biomet.- dhr review: the device manufacturing quality records indicate that the released component met all requirements to perform as intended.Conclusion: the alloclassic hip prosthesis with metasul pairing had to be revised after more than 23 years in vivo due to a tripping fall of the patient resulting in a periprosthetic acetabular fracture.Until then the patient was free of complaints and the stem was revised because of the approach used.During revision surgery the stem was found firmly fixed while the cup was obviously loose.For both it was reported that if at all only few signs of bone ongrowth could be recognized.After cleaning and disinfection the alloclassic sl stem as well as the alloclassic csf shell show bone attachments on their anchoring surfaces.Signs of loosening in the form of polished spots/lines could not be observed.It seems that the eccentric metasul head was appropriately anchored on the taper of the stem as the latter showed indentations of the head taper¿s four arrow-shaped marks serving as elements for rotational stability [2].On the head taper surface changes over the entire contact area with the stem taper could be found.The greenish- whitish deposits seen on both, taper surface of head and stem, could point to corrosion products.Blackish deposits partially present in the stem taper¿s groove structure also indicate corrosion products whereas the blackish discoloration of the taper rather indicates a thicker oxide film.The co and cr values (whole blood) at hand were measured approximately six weeks after revision and are not elevated according to the indicated reference values.It also has to be considered that the patient has still a hip replacement with metasul pairing on the other side.Compared to [1] the annual wear rate is low.In general the articulation surfaces of the metasul pairing are not conspicuous.On the articulation surface of the head an almost complete borderline between the loaded and the unloaded area could be recognized under certain lighting conditions.The appearance of the smearings detected on the inlay (smearing on top of the rim and on the spherical calotte adjacent to the bevel) does not point to a long-term phenomenon, also as they could only be discovered by closer inspection with a low power microscope.It could be suggested that they could possibly have derived from dislocating the joint during revision surgery the investigation did not identify a nonconformance or a complaint out of box (coob).- references (b)(6).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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