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Analysis of historical records: the bone screws involved in this event have not yet been received by orthofix (b)(4) (the tip was left on patient bone while the stem is not available).Unfortunately also the code and the lot number have not been made available and therefore it was not possible to perform the verification of the historical data (please kindly refer to mfr report 9680825-2016-00064).Technical evaluation: the involved bone screws have not yet been received by orthofix (b)(4) (the tip of the screws is still on patient while the stem is not available).The technical evaluation of the bone screws will be performed as soon as it becomes available (please kindly refer to mfr report 9680825-2016-00064).Medical evaluation: the information made available on the event together with the x-rays were sent to our medical evaluator.Please find below an extract of the medical evaluations performed."the event occurred in a (b)(6) male patient who had a hypertrophic non-union of the right tibia.The non-union is oblique, and there is a varus of 18 degrees and a recurvatum of around 14 degrees.There is also some translation.Although the non-union is stiff, and weightbearing is possible, this non-union will never heal if left alone, because of the deformity and because the bone is inherently unstable because of the obliquity of the fracture.The surgeon elected to do a transverse osteotomy just distal to the non-union, within 20 mm at the closest point.He applied a frame with a 2 ring tl-hex system round the osteotomy and non-union, and a second ring some distance proximally.Each of the proximal rings carried 2 bone screws, whereas the distal ring had 2 wires and 2 bone screws.There are some points for discussion.The concept here was to correct the deformity with a separate osteotomy with the tl-hex system, and leave the non-union alone, hoping that it would unite when it was off-loaded by the frame.My concerns would be that the osteotomy is very close to the non-union, within 20 mm at the closest, and i would question the vascularity of the intermediate fragment.I can see that the additional osteotomy might stimulate further activity in the non-union, but the continued loading of the leg will mean that the mechanics of the non-union are unchanged.In the latest x-rays there are no signs of callus at the new osteotomy, which tends to support the view that the small intermediate fragment is now avascular.The choice of fixation method has resulted in different mechanics each side of the osteotomy: proximally there are 4 widely spaced screws, and distally there are 2 screws close together and 2 wires below them.Much of the cyclic loading produced by weightbearing will have been concentrated at these two screws, which i am sure failed because of heavy cyclic loading.In my view a different frame design with 4 wires distally on two close rings would have provided secure even loading on the fixation elements.Mixing the distal fixation elements was not a good idea if this patient was to weightbear.We know that screw failure is a rare event and usually occurs because of exceptional loading over a prolonged period; i am sure that this was the case here.I am also very uncertain why the fixation was removed when the two screws broke.In my view they could have removed the broken screws and inserted two more tensioned wires to provide good fixation to continue.As it is the deformity is no better and there are now two non-unions very close to each other, which is why they are considering resection of the non-union and the small distal fragment and restoring length by callotasis.It might well be better to close the distal gap created by resection by gradual compression, and make a fresh proximal osteotomy for lengthening".Final comments: the involved bone screws have not yet been received by orthofix (b)(4) (the tip of the screws is still on patient while the stem is not available).The technical evaluation of the bone screws will be performed as soon as it becomes available (please kindly refer to mfr report 9680825-2016-00064).The medical evaluation evidenced as follows: "mixing the distal fixation elements was not a good idea if this patient was to weightbear.We know that screw failure is a rare event and usually occurs because of exceptional loading over a prolonged period; i am sure that this was the case here.".Based on the evidences deriving from the sole medical evaluation, orthofix (b)(4) can conclude that the problem that occurred is attributable to the selected mechanical configuration which caused the breakage of the two bone screws mostly solicited.Orthofix (b)(4) continues monitoring the devices on the market.Device not returned.
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The information initially provided by the local distributor indicates: product codes: unknown (potential codes 99-611540 and/or 99-612660); batch numbers: unknown; quantity: 2; hospital name: (b)(6); surgeon name: (b)(6); date of surgery: (b)(6) 2016; body part to which device was applied: tibia; surgery description: correction/ non union; patient information: (b)(6), male patient with hypertrophic pseudoarthrosis; problem observed during: treatment; type of problem: device functional problem; event description: "the patient before the operation showed a hypertrophic pseudoarthrosis at the distal mid-shaft tibial that did not caused pain and that allowed the load.The tibia also had a varus deformity to correct.In (b)(6), dr.(b)(6) operated the patient with a tl hex to correct the varus but without resection of the fibrotic tissue of pseudarthrosis because he hoped not to have to resect because the patient had no pain and could load.Initially, the correction was fine and the callus was generating under the pseudoarthrosis at the osteotomy level.Then in may he converted the tl hex in truelok and the two distal xcaliber screws broke under total load (the patient loaded all the weight).To date the frame was removed, the bone tissue can be seen in the enclosed images, and it will be needed to be done a resection and bone transport." the complaint report form also indicates: the devices failure had adverse effects on patient (portion od the devices left in patient tibia); the surgery was completed with the used devices; the event did not lead to a clinically relevant increase in the duration of the surgical procedure; an additional surgery was required (intervention not yet planned); copies of the operative reports are not available; copies of the x-rays images are available; patient current health condition: the patient has two broken screws in the tibia and he has to have another intervention (resection and bone transport).On july 22, 2016, orthofix (b)(4) received the following additional information: "the stem of the bone screws is not available".On august 4, 2016, orthofix (b)(4) received the following additional information: it was not possible to get from the hospital the code and lot of the two broken screws.The potential code and lot of the two broken bone screws is included in the following list: code 99-611540 lot v1400691; code 99-612660 lot v1374583 and/or v1404111.Please also kindly refer to mfr report 9680825-2016-00064.(b)(4).
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