title: Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis: a case series.
abstract: OBJECTIVE
  We present a case series of five patients who had revision surgery following magnetic controlled growing rods (MGCR) for early onset scoliosis. Metallosis was found during revision in four out of five patients and we postulated a mechanism for rod failure based on retrieval analysis.
  
  
  METHODS
  Retrieval analysis was performed on the seven explanted rods. The mean duration of MCGR from implantation to revision was 35 months (17 to 46). The mean age at revision was 12 years (7 to 15; four boys, one girl).
  
  
  RESULTS
  A total of six out of seven rods had tissue metallosis and pseudo-capsule surrounding the actuator. A total of four out of seven rods were pistoning. There were two rods which were broken. All rods had abrasive circumferential markings. A significant amount of metal debris was found when the actuators were carefully cut open. Analytical electron microscopy demonstrated metal fragments of predominantly titanium with a mean particle size of 3.36 microns (1.31 to 6.61).
  
  
  CONCLUSIONS
  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.
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: K H
authors.initials: KH
authors.lastname: Teoh
authors.affiliation: Cardiff University, Heath Park, Cardiff, CF14 5DX, UK.
authors.forename: C
authors.initials: C
authors.lastname: von Ruhland
authors.affiliation: Cardiff University, The Parade, Cardiff CF24 3AA, UK.
authors.forename: S L
authors.initials: SL
authors.lastname: Evans
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: S H
authors.initials: SH
authors.lastname: James
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: A
authors.initials: A
authors.lastname: Jones
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: J
authors.initials: J
authors.lastname: Howes
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: P R
authors.initials: PR
authors.lastname: Davies
authors.affiliation: University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK.
authors.forename: S
authors.initials: S
authors.lastname: Ahuja
mesh_terms: D001858:Bone Nails / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D005547:Foreign Bodies / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008280:Magnetics; D008297:Male; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation / Q000379:methods; D012600:Scoliosis / Q000601:surgery*; D014025:Titanium / Q000032:analysis
chemical_list: D014025:Titanium
keywords: Early onset scoliosis; Magnetic controlled growing rods; Metallosis