|
The information initially provided by the local distributor indicates: - product code: 99-611530.- batch number: b1266930 or b1268235.- quantity: 1.- hospital name: (b)(6).- surgeon name: unknown.- date of surgery: (b)(6) 2019.- body part to which device was applied: left tibia - bone lengthening.- surgery description: correction.- patient information: female.- problem observed during: into treatment/post-operative.- type of problem: device functional problem.- event description: "the distal middle screw broke during left tibia extension.We have been contacted by doctors for instructions on how to replace and remove screws.The surgeon asked to us that are similar events occurring at other hospital.The surgeon will perform a screw replacement operation on (b)(6) but no information is available on the specific procedure.The screw broke on (b)(6).The surgeon suggests that other screws may also be broken".The complaint report form also indicates: - the device failure had adverse effects on patient.- the initial surgery was completed with the device.- the event did not lead to a clinically relevant increase in the duration of the surgical procedure.- an additional surgery was required (date: (b)(6) 2020).- copies of the operative reports are not available.- copies of the x-ray images are not available.- patient current health condition: unknown.On february 27, 2020, orthofix srl received the following additional information: - name of the surgeon: "dr.(b)(6) and dr.(b)(6) ".- patient age and weight: "female, 13 years old, 45 kg".- patient diagnosis and proposed treatment: "the treatment proposed is unknown because dr.Kawamura moved in october.We determined from the radiographs that the patient was short stature (osteogenesis imperfecta)".- lengthening planned and lengthening achieved before screw breakage: "the extension distance when the screw was broken was 67 mm.It was originally planned to be extended by 70mm".- copies of the x-rays images are available.- patient current health condition: "the plate is adapted to the affected area of the patient".- three screws were broken in total (mfr report 9680825-2020-00028 and 9680825-2020-00029 and 9680825-2020-00030).Further information and x-ray images received on april 13, 2020: on april 13, 2020, the distributor informed that another bone screw broke on this patient (mfr report 9680825-2020-00035).This last event was identified with number (b)(4).Below are reported the information included in the complaint form provided in regards to this last breakage.- device code: 99-611530.- batch number: b1266930 or b1268235.- quantity: 1.- hospital name: (b)(6).- surgeon name: dr.(b)(6).- date of initial surgery: (b)(6) 2019.- body part to which device was applied: right tibia - bone lengthening.- surgery description: correction.- patient information: 14 years, female, 45 kg.- problem observed during: into treatment/post-operative.- type of problem: device functional problem.- event description: "the distal screw of proximal clamp broke during right tibia extension.This complaints is the same patient of (b)(4).The patient has experienced broken four screws.The surgeon continues to treat the patient because there is only one screw broken in the patient's right foot.We are asked to explain to the patient family what caused the screw to break.We would like a medical advisor to seek advice".The complaint report form also indicated: - the device failure did not have any adverse effects on patient.- the initial surgery was completed with the device.- the event did not lead to a clinically relevant increase in the duration of the surgical procedure.- an additional surgery was not required.- a medical intervention (outpatient clinic) was not required.- copies of the operative reports are not available.- copies of the x-ray images are available.- availability of the device: once the bone extension is complete and the screw is removed as scheduled, we can ship it to you.- the event should be notified to the japanese competent authority.- patient current health condition: the patient's right foot still has an external fixator.Manufacturer ref: (b)(4).Distributor ref: (b)(4).
|
|
Analysis of historical records: orthofix srl checked the internal records related to the controls made on the device code 99-611530 lot b1266930 (lot marked on the component is g180431) before the market release.No anomalies have been found.The original lot, manufactured in 2018, was comprised of 100 units.All of them have already been distributed to the market.According to orthofix srl historical records, no other notifications have been received for this specific device lot.Orthofix srl checked the internal records related to the controls made on the device code 99-611530 lot b1268235 (lot marked on the component is g180431) before the market release.No anomalies have been found.The original lot, manufactured in 2018, was comprised of 200 units.All of them have already been distributed to the market.According to orthofix srl historical records, no other notifications have been received for this specific device lot.Orthofix srl checked the internal records related to the controls made on the component code 611530 lot g180431 before the market release.No anomalies have been found.The original lot, manufactured in 2018, was comprised of (b)(4), which were assembled in several lots of finished devices.All of them have already been distributed to the market.According to orthofix srl historical records, no other notifications have been received for this specific component lot.Technical evaluation the returned devices, received on march 17, 2020, were examined by orthofix srl quality engineering department.In particular it was received all the bone screws used to treat the left tibia of the patient.The devices were subjected to visual and dimensional check as per orthofix srl specifications.The visual check confirmed the problem notified.Three bone screws are broken.All marked with the lot g180431.The dimensional check, performed where possible, did not evidence any anomalies.The verification of the raw material certificate, used to produce the screws, showed that the material is conforming to orthofix srl specifications.The broken devices were then sent to an external laboratory to verify the material conformity and for further investigation.Please find below an extract of the technical evaluation received: "according to the findings, the failed item consists of an aisi 316 lvm austenitic stainless steel as expected, with a regular microstructure of austenitic matrix, with the presence of shear bands, indicating some degree of cold-working.The average core hardness value (after three readings) is around 330 hv10 for every sample, consistent with the observed microstructure.The fracture was nucleated in the correspondence of a thread root.The section analysis shows the presence of small secondary cracks, sometimes multiple, on near threads.In correspondence of the nucleation, no microstructural anomalies, nor relevant surface notches can be observed.The fractographic clues consistently indicate a fatigue propagation fracture, likely due to a flexural load.This type of load is coherent with expected usage modality for the screw and may be related to an excessive, or unbalanced, load distribution." medical evaluation: the information made available on the event together with the results of the technical evaluation were sent to our medical evaluator.Please find below an extract of the medical evaluations performed.(b)(6) 2020: "this event took place in japan, where a patient was having bilateral tibial lengthening.The report states that information is hard to discover because the original surgeon seems to have moved to another hospital.The original report states that the patient had the fixation applied on (b)(6) 2019, which is just over 9 months ago.An lrs with osteotite screws size 150/30 was in place and the middle distal screw has broken.It looks as though the proximal screw on each side is 150/40 and the remaining screws 150/30, which is correct for these tibiae.Later information adds that the patient is 13 years old and is having bilateral tibial lengthening.The patient has short stature and a diagnosis of osteogenesis imperfecta is suggested.An x-ray series has been sent from the time of just before fixator application until (b)(6) 2020.The x-rays show a very well applied adult lrs fixator on each tibia.There are no open epiphyses and there is no sign of osteogenesis imperfecta.I do not think that any surgeon would be doing bilateral lengthening with external fixation on a patient with this diagnosis, so we can exclude that.I also suggest that the patient is significantly older than 13, probably late teenage or in her 20's.The pelvis (not all is visible) seems to be in proportion to the femora and the patient may have short stature with normal bones, not achondroplasia.It is unusual to see such well applied external fixation, although i have grown accustomed to it from japan.There are 3 screws in each clamp; they are all in the 1-3-5 positions in each clamp and are perfectly parallel to each other.The thread length is perfectly chosen.It is a text-book example of a tibial lengthening application.The osteotomy is diaphyseal but that cannot be avoided in such short bones.The series of xrays show gradual lengthening and later good callus formation up to the (b)(6) x-ray, when a single broken screw is obvious with separation (screw 5, counting from proximal), and screw 4 is also broken but in continuity.Just before secondary surgery on (b)(6) it is now obvious that 3 screws have broken, 2, 4 and 5 on the left side, none on the right.This is quite extraordinary for several reasons: - the working length of each clamp (distance from osteotomy) is the same, so the loading will be very similar.- all screws are spaced widely in each clamp for maximum fixation strength.- 6.0 - 5.6 mm osteotite screws are used throughout, which is quite correct.- the first screw of each clamp to break seems to have been the middle screw of each clamp, which should be the most protected screw.- normally the screw nearest the osteotomy has the greatest load and if any are to break this is the first.I have never seen this happen before, and it is difficult to understand why it has happened.The patient has had 2 locking plates applied to the left leg after the fixator and screws were removed.It seems that the length gained has been preserved.I think that the very extensive fixation applied to the left leg may be partly die to the fact that the surgeon had to remove a cylinder of bone with each osteotite screw fragment, potentially weakening the bone.This is a most extraordinary sequence of events and i cannot offer a biomechanical reason for it".April 18, 2020 with the information about the last broken screw: "the saga with this patient in japan continues.Once again an osteotite screw has broken in this very well applied frame.The photographs of the screws sections that you also sent provide classic examples of fatigue fractures.I think that i now know why this series of events has happened.This patient is having bilateral tibial lengthening.The patient has 6 osteotite screws to each fixator, evenly spaced so that the load will be spread evenly.The patient is 13 years old and 45 kg in weight.I think that this patient has no alternative but to fully weight bear on each leg.I think that because the fixation with the ha coated screws is so good, it feels very secure to the patient, who is very active as a result.This patient has been too active because the fixation is so good.There should be limited partial weightbearing until continuous callus is visible on the x-rays, using crutches and a wheelchair for longer distances.I feel certain that these breakages have happened because the patient has been very active.We should explain to the distributor that breakage of these screws is excessively rare.When it does occur it is because the fatigue life of the bone screw has been reached by repeated cyclic loading.I would love to see a video of this patient moving about.So we can be sure that these screws have been loaded beyond their design criteria, causing fatigue failure of the screws".April 22, 2020 with the results of the technical analysis performed on the returned broken screws: "the technical report confirms our thoughts that these screws had been subject to excessive flexural loading which has caused fatigue failure of the screws.The screws themselves are fully to specification.As stated already, this is excessively rare and will be due in part to the excellent grip on the bone of the ha coated screws, which has lead to excessive loading of the frame.The patient should not have been walking for much of the time, because this was a bilateral lengthening, so partial weightbearing was impossible.I agree with the conclusions of the report".Conclusion: the results of the technical evaluation concluded that the three returned broken screws were originally conforming to orthofix specifications.The breakages occurred are mainly attributable to fatigue failure most likely related to an excessive cyclic load applied.Orthofix can assume that the outcome of this evaluation is also applicable to the fourth screw that broke on the same patient, which is still in use by patient and therefore not available for the evaluation.The medical evaluation evidenced as follows: "the technical report confirms our thoughts that these screws had been subject to excessive flexural loading which has caused fatigue failure of the screws.The screws themselves are fully to specification.As stated already, this is excessively rare and will be due in part to the excellent grip on the bone of the ha coated screws, which has lead to excessive loading of the frame.The patient should not have been walking for much of the time, because this was a bilateral lengthening, so partial weightbearing was impossible".Based on the results of the technical evaluation, and on the evidences deriving from the medical evaluation, orthofix srl can conclude that the problem that occurred is not device related.The analysis of the historical data evidenced that no other notifications have been received on devices belonging to the same lot.Orthofix continues monitoring the products on the market.Please also kindly refer to mfr report 9680825-2020-00028 and 9680825-2020-00030 and 9680825-2020-00035.
|
