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Metal-on-metal hips: cobalt can induce an endotoxin-like response
  1. Alison Jane Tyson-Capper1,
  2. Helen Lawrence1,
  3. James P Holland2,
  4. David J Deehan2,
  5. John A Kirby1
  1. 1Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
  2. 2Department of Orthopaedics, Freeman Hospital, Newcastle upon Tyne, UK
  1. Correspondence to Dr Alison Jane Tyson-Capper, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, William Leech Building, Framlington Place, Newcastle upon Tyne NE2 4HH, UK; Alison.tyson-capper{at}

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Recent studies have highlighted significant risks associated with metal-on-metal (MoM) hip joint replacement,1 leading Smith et al 2 to recommend that research should be ‘focused on understanding the biological consequences of exposure to orthopaedic metals’. One of these consequences may be the development of solid or fluid-filled inflammatory lesions, termed pseudotumours, which have been reported in areas around MoM joints.3 ,4

The articulating surface of MoM joints is fabricated from a hard alloy containing approximately one part chromium to two of cobalt. Ionic forms of both these metals can be detected at a high level (≤5 mM Cr, ≤0·25 mM Co) in the synovial fluid surrounding MoM joints, with lower levels present in distant body tissues, blood and urine.5 Although …

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  • Contributions All authors contributed to the concept of the study and study design. HL was involved in data collection and data analysis. AJT-C and JAK were involved in preparation of the figure, data analysis, data interpretation and writing the manuscript.

  • Funding This work is supported by the Newcastle NIHR Biomedical Research Centre.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.