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Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 12,
1655-1659.
doi: 10.1302/0301-620X.89B12.19714 Copyright © 2007 by British Editorial Society of Bone and Joint Surgery The effect of metal ions in solution on bacterial growth compared with wear particles from hip replacementsH. A. Anwar, BMedSci, MBBS, MRCS, Specialty Registrar in Trauma and Orthopaedics1; C. H. Aldam, MBBS, FRCS, Consultant Orthopaedic Surgeon1; S. Visuvanathan, MSc, MD, FRCPath, Consultant Microbiologist1; and A. J. Hart, MA, FRCS(Orth), Senior Lecturer and Honorary Consultant Orthopaedic Surgeon2
1 The Princess Alexandra Hospital NHS Trust, Hamstel Road, Harlow CM20 1QX, UK. Correspondence should be sent to Mr H. A. Anwar at Basildon and Thurrock Hospitals NHS Trust, Nethermayne, Basildon SS16 5NJ, UK.; e-mail: hannyanwar{at}yahoo.co.uk
The biological significance of cobalt-chromium wear particles from metal-on-metal hip replacements may be different to the effects of the constituent metal ions in solution. Bacteria may be able to discriminate between particulate and ionic forms of these metals because of a transmembrane nickel/cobalt-permease. It is not known whether wear particles are bacteriocidal. We compared the doubling time of coagulase negative staphylococcus, Staphylococcus aureus and methicillin resistant S. aureus when cultured in either wear particles from a metal-on-metal hip simulator, wear particles from a metal-on-polyethylene hip simulator, metal ions in solution or a control. Doubling time halved in metal-on-metal (p = 0.003) and metal-on-polyethylene (p = 0.131) particulate debris compared with the control. Bacterial nickel/cobalt-transporters allow metal ions but not wear particles to cross bacterial membranes. This may be useful for testing the biological characteristics of different wear debris. This experiment also shows that metal-on-metal hip wear debris is not bacteriocidal.
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