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An adverse event was entered into the illuminoss clinical study registry on (b)(6) 2022 for an event which occurred on (b)(6) 2019.A 59 y/o female patient was treated on (b)(6) 2018 with illuminoss implant for a pathological fracture of the right humerus.The patient experienced pain at the treated site over the course of follow-up visits, and 296 days post implantation on (b)(6) 2019 the patient received surgical intervention to explant the illuminoss implant, resect the central segment of tumor from the mid humerus, and reconstruct it with a cemented intercalary metal replacement to achieve stabilization of the original bone fracture.
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Information provided by the hospital/treating institution: an adverse event was entered into the illuminoss clinical study registry on (b)(6) 2022 for an event which occurred on (b)(6) 2019.The patient was treated for a pathologic fracture of the right humerus due to renal cell carcinoma metastasis.Pre operative x-rays were taken on (b)(6) 2018 which show a pathologic fracture of the right humerus with a significant mid humeral bone defect, the ao classification was diaphyseal and the fracture type was wedge, bending, closed.The patient's right humerus was treated with an illuminoss 17x220mm implant on (b)(6) 2018.The treating physician noted that there was significant bone loss at the time of final reduction, a sling was used as the method of fracture support post op, and there was no supplemental fixation.Follow up x-rays were taken on (b)(6) 2018 (47 days post op) and on (b)(6) 2018 (116 days post op).These 47-day post op x-rays show that the implant width was approximately 17mm at the widest part of the implant at the fracture location, and about 8.5mm at the implant portion immediately distal to the fracture with cortical wall contact.The adverse event occurred on (b)(6) 2019 (296 days post op) which the treating physician entered into the registry as "pain and/or loss of function".The x-rays from (b)(6) 2019 show the illuminoss implant had broken and there was a loss of fixation and stabilization.The illuminoss implant was removed, the central segment of the tumor resected from the mid humerus and reconstructed with a cemented intercalary metal replacement.Root cause investiation: no returned product evaluation available as the implant removed in 2019 was not returned to the manufacturer.Manufacturing records of the device (17x220mm implant, lcn 380231) were reviewed and found to be in specification at the time of manufacture and release.To aid in the root cause investigation illuminoss held a medical oversight meeting on (b)(6) 2022.The information provided by the treating institution and x-rays were reviewed.Comparing the date of implantation (performed on (b)(6) 2018) to the date of the report of the broken implant (b)(6) 2019) identified that ~10 months (or 296 days) had elapsed between the initial implantation and the implant break.The pre-op x-rays from (b)(6) 2018 show the distal canal of the humerus is small.The 47-day post op x-rays show the balloon diameter just distal to the fracture to be about 8.5mm in width, while the balloon diameter is about 17mm in width at the fracture directly proximal.The follow up x-rays from (b)(6) 2018 also show that there is a fracture callous present which is indicative of motion at the fracture site.This patient had renal cell metastasis, which illuminoss medical oversight notes is routinely treated with radiation therapy which can reduce the likelihood of bone healing, though it was not entered into the registry if this patient had completed any radiation therapy.The post op x-rays on (b)(6) 2019 on the adverse event onset date show the implant has broken at the very distal end of the fracture.The illuminoss implant is a space filling implant in which the balloon will expand to its maximum size unless limited by contact with the walls of the intermedullary canal.In this situation the pathologic fracture of the humerus allowed the implant to expand to its maximum width of approximately 17mm at the fracture site, as there was little to no cortical wall present in some areas of the fracture to limit the balloon inflation size.The intermedullary canal distal to the fracture is very narrow in comparison, only allowing for about an 8.5mm implant width between the cortical walls.This created an implant shape in which there is a very wide portion of implant at the fracture site, and an abrupt significant reduction in width directly below that point.Illuminoss medical oversight noted that this shape would cause a stress riser in the implant at the point the implant drastically reduces in width.It was also noted in this review that this identified point of probable stress riser in the implant is the location of the eventual implant break.The review of x-rays identified that the initial fixation was likely insufficient.There is evidence of fracture callous on the bone 116 days post op on the (b)(6) 2018 x-rays, indicating movement at the fracture site.There was also significant bone loss noted at the time of initial implantation.The fracture was also a nonunion at 296 days post op.Movement at the fracture site over this period of time will cause extended implant stress.Insufficient initial fixation in this case is most likely due to the extent of the bone loss at the fracture site at the time of initial implantation.Illuminoss medical oversight concluded that the implant break may have been due to a combination of reasons including insufficient initial fixation due to the nature of the fracture and significant bone loss observed at the time of initial treatment, extended implant stress due to nonunion and the resulting fracture movement, and an implant stress riser due to the shape of the implant (an abrupt and significant reduction in diameter) that resulted from the shape of the anatomy at and below the fracture site.The most likely cause of the implant break based on the medical records reviewed is due to insufficient initial fixation due to the quantity/quality of bone at the fracture site (also noted by the treating physician), resulting in a non-union and movement (as evidenced by the progression of facture callous visible on the follow up x-rays) that caused an implant stress riser.The implant shape with a large diameter portion at the fracture site and a drastic reduction in diameter in the distal intermedullary canal also likely contributed to the formation of the stress riser and eventual implant break, and this implant shape was partially due to the lack of bone at the fracture which allowed the implant to expand to approximately it's full diameter at this location.Review of ifu and potential user error instructions for use 900356_w was reviewed and found to contain the risk "as with any im fixation system or rod the following can occur: loosening, bending, cracking, fracture, or mechanical failure of the components or loss of or inadequate fixation in bone attributable to delayed union, nonunion, insufficient quantity or quality of bone, markedly unstable comminuted fractures, or insufficient initial fixation, loss of anatomic position with nonunion or malunion with rotation or angulation." conclusion the root cause of the broken implant is due insufficient initial fixation due to insufficient quantity or quality of bone at the fracture site, resulting in an implant stress riser immediately below the fracture side, which over time lead to the implant break.
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