Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis

Teoh, Kar Hao; Ruhland, Christopher Von; Evans, Samuel Lewin; James, Stuart H.; Jones, Alwyn; Howes, J; Davies, Paul; Ahuja, Sashin

doi:10.1302/0301-620x.98b12.38061

Cited by 71 publications

(53 citation statements)

References 10 publications

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“…Since the publication of the NICE recommendation, there have been examples of MCGR failures discussed at a consensus meeting [ 2 ] and in the literature [ 3 - 9 ]. There have also been analyses of explanted rods [ 10 - 12 ]. Discussions regarding the failure of MCGRs have attempted to determine a mechanical failure rate but have used data that were compiled from multiple centers, conducted with few cases, or followed up for only a short time.…”

Section: Introductionmentioning

confidence: 99%

Magnetically Controlled Growing Rods: The Experience of Mechanical Failure from a Single Center Consecutive Series of 28 Children with a Minimum Follow-up of 2 Years

et al. 2018

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Study DesignRetrospective observational study of a continuous series of 28 children.PurposeTo determine the mechanical failure rate in our cohort of children treated with magnetically controlled growth rods (MCGRs).Overview of LiteraturePrevious studies report a MCGR mechanical failure rate of 0%–75%.MethodsAll patients with MCGR implantation between 2012 and 2015 were examined and followed up for a minimum of 2 years. A retrospective evaluation of contemporaneously documented clinical findings was conducted, and radiographs were retrospectively examined for mechanical failure. The external remote controller (ERC)-specified length achieved in the clinic was compared to the length measured on subsequent radiographs.ResultsFourteen mechanical failures were identified in 28 children (50%) across a total of 52 rods (24 pairs and four single constructs). Mechanical failures were due to: failure to lengthen under general anesthesia (seven children), actuator pin fracture (four), rod fracture (one), foundation screw failure (one), and ran out of rod length (one). Of the 14 mechanical failures, six were treated with final fusion operations (reflecting limited further growth potential), and eight patients were treated with the intention for further lengthening. We therefore consider these eight patients to represent the true incidence of mechanical failure in our cohort (29%). The difference between the ERC length and radiographic length was found to be identical in 11% cases; 35% were overestimates, and 54% were underestimates. The median underestimate was 2.45 mm whereas the median overestimate was 3.1 mm per distraction episode. In total, 95% of all ERC distractions were within ±10 mm of the radiographic length achieved over a median of nine distraction episodes.ConclusionsOur series is the most comprehensive MCGR series published to date, and we present a mechanical failure rate of 29%. Clinicians should be mindful of the discrepancies between ERC length and radiographic measurements of rod length; other modalities may be more helpful in this regard.

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Section: Introductionmentioning

confidence: 99%

Magnetically Controlled Growing Rods: The Experience of Mechanical Failure from a Single Center Consecutive Series of 28 Children with a Minimum Follow-up of 2 Years

et al. 2018

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“…Considering the structural intactness in the rods of most planned revisions, increased in-situ time is suggested to be another possible contributing factor to the increased material loss from implanted rods, which do not necessarily present any structural damages. The increased material loss detected in the current study also provides evidence for the regional in ammatory reaction and increased serum ion levels reported in patients receiving the rods [8,18]. Long-term follow-ups are needed to understand the impact of increased material loss on patients' health.…”

Section: Discussionmentioning

confidence: 53%

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

Wei

Hothi

Morganti

et al. 2020

Preprint

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Background: To assess the relationship between mechanical wear and the failure of the internal lengthening mechanism in retrieved MAGnetic Expansion Control (MAGEC) growing rods. Methods: This study included 34 MAGEC rods retrieved from 20 patients. The state of the internal mechanism and mechanical wear were assessed in all the rods using plain radiographs and visual inspection. Metrology was then performed to assess the topography and mechanical wear of the telescopic bars, using a Talyrond 365 (Taylor Hobson, Leicester, UK) roundness measuring machine. Results: Plain radiographs showed evidence of a broken internal mechanism in 29% of retrieved rods. Single-side wear marks were found in 97% of retrieved rods. Material loss was found to significantly increase in rods with a damaged internal mechanism (p<0.05) and rods with longer time in situ (r=0.692, p<0.05). Conclusions: We found an association between damage to the internal mechanism of the rods and (1) patterns of single-side longitudinal wear marks and (2) increased material loss. As the material loss was also found to increase over time of rod in situ, we emphasise the importance of early detection and revision of failed MAGEC rods in clinical practice.

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“…46 These findings of device failure (failure of distraction or component breakage) in association with adjacent soft tissue metallosis were confirmed by further case series reports. Teoh et al 47 described gross histological findings of 7 MCGRs explanted from patients receiving MAGEC and requiring revision surgery between 2011 and 2015. All rods exhibited abrasive circumferential markings, 6 rods showed metallosis around the actuator, 4 rods were pistoning (nonfunctioning) and 2 rods had fractured.…”

Section: Implant Failurementioning

confidence: 99%

<p>Magnetic Controlled Growth Rods in the Treatment of Scoliosis: Safety, Efficacy and Patient Selection</p>

Roberts

2020

MDER

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Early-onset scoliosis is defined as a spinal curvature greater than 10°in children prior to 10 years of age. Untreated EOS may lead to progressively severe spinal deformity, impaired pulmonary development, restrictive lung disease, and both increased morbidity and mortality. Limitations of established conservative treatments include inability to correct severe deformity, as well as challenges with compliance when casting and bracing is applied. In addition, surgical treatment in the form of traditional growing rods requires regular surgical lengthenings and is associated with complications inherent with repeated invasive procedures and exposure to general anesthesia. MAGEC is an evolving magnetically controlled growing rod system for the treatment of EOS. After initial implantation, lengthening is achieved non-invasively by using magnetic external remote control. MAGEC offers the potential to control moderate and severe EOS, while avoiding repeated surgical procedures and associated complications. In this review, we examine the results from clinical, radiological and explant studies following the use of MAGEC, in the context of other established and emerging treatments for EOS.

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Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis

Abstract: This study highlights concerns with tissue metallosis in MCGR. We recommend careful follow-up of patients who have received this implant. Cite this article: Bone Joint J 2016;98-B:1662-7.

Cited by 71 publications

References 10 publications

Magnetically Controlled Growing Rods: The Experience of Mechanical Failure from a Single Center Consecutive Series of 28 Children with a Minimum Follow-up of 2 Years

Magnetically Controlled Growing Rods: The Experience of Mechanical Failure from a Single Center Consecutive Series of 28 Children with a Minimum Follow-up of 2 Years

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

<p>Magnetic Controlled Growth Rods in the Treatment of Scoliosis: Safety, Efficacy and Patient Selection</p>

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