No announcement yet.

Calling Ed... material failures of magnetic growth rods

  • Filter
  • Time
  • Show
Clear All
new posts

  • Calling Ed... material failures of magnetic growth rods

    Analysis of Explanted Magnetically Controlled Growing Rods from 7 UK Spinal Centers.
    Joyce, Thomas J. PhD; Smith, Simon L. PhD; Rushton, Paul R.P. MRCSEd; Bowey, Andrew J. FRCS(Tr&Orth); Gibson, Michael J. FRCS
    Spine: Post Acceptance: April 28, 2017
    doi: 10.1097/BRS.0000000000002221
    Biomechanics: PDF Only
    Study Design. Analysis of explanted MAGnetic Expansion Control (MAGEC) growing rods.

    Objective. To analyze explanted MAGEC rods used in management of early onset scoliosis and identify the mode of failure in such cases.

    Summary of Background Data. Magnetically controlled growing rods are increasingly used as the option of choice for early onset scoliosis. However, being more complex than conventional growing rods they are perhaps more likely to succumb to multifarious failure modes. In addition, metallosis has been reported around failed MAGEC rods.

    Methods. Explanted MAGEC rods from 7 UK spinal centers were obtained for independent analysis. Thirty-four MAGEC rods, from 18 children, explanted for reasons including failure of rod lengthening and maximum rod distraction reached, were cut open to allow internal components to be evaluated and assessed.

    Results. Externally, all MAGEC rods showed localized marks, which were termed 'growth marks' as they indicated growth of the rod in vivo, on the extending bar component. After cutting open, titanium wear debris was found inside all 34 (100%) MAGEC rods. Ninety-one percent (31/34) of MAGEC rods showed measurable wear of the extending bar, towards the magnet end. Substantial damage to the radial bearing was seen inside 74% (25/34) of MAGEC rods while O-ring seal failure was seen in 53% (18/34) of cases. In 44% (15/34) of MAGEC rods the drive pin was fractured but this was felt to be an effect of rod failure, not a cause.

    Conclusions. The combination of high volumes of titanium wear debris alongside O-ring seal damage likely accounts for the metallosis reported clinically around some MAGEC rods. Based on this explant data, a failure mechanism in MAGEC rods due to the natural off axis loading in the spine was proposed. This is the largest data set reporting a complete analysis of explanted MAGEC rods to date.

    Level of Evidence: 4

    Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine

    "We are all African."

  • #2
    Oh Sharon.....This is just so saddening for me to hear this, and especially having it happen with the kids....

    Years ago, if you remember, we had threads here on the Pro-disc style movable artificial disc implants, and I remember bringing up the particulate issues that can arise with any movable implant. Its a curse. I am not sure but I think one of the Auusie ladies had an artificial implant placed under an old Harrington construct around 10 years ago. I have no idea on how she is doing.

    Metallosis being debris from the wear of "movable surfaces" is not something you want happening. There are plenty of hip recall photos showing how nasty this can be. Necrosis and infection can cause terrible pain. Having this happen around the spine cannot be good.

    In the human body, material selection is mainly about biocompatability per the study I attached. If something is breaking or failing, its up to the guys at Magec to figure this out.

    Its been 4 years since Anthony and he was the 1st with the system. If any other kids have this system, with fully extended rods, now they have to think about pulling out the system since it has a history of failure. (smug face)

    49 yr old male, now 63, the new 64...
    Pre surgery curves T70,L70
    ALIF/PSA T2-Pelvis 01/29/08, 01/31/08 7" pelvic anchors BMP
    Dr Brett Menmuir St Marys Hospital Reno,Nevada

    Bending and twisting pics after full fusion

    My x-rays


    • #3
      Thanks for looking at this, Ed.
      Sharon, mother of identical twin girls with scoliosis

      No island of sanity.

      Question: What do you call alternative medicine that works?
      Answer: Medicine

      "We are all African."