Relationship Between Metal Wear Debris Speculation and Immune Dysfunction in Patients

Institution: Imperial College London / RNOH
Principal Investigators: : Mr Alister Hart, Professor Powell (MRC Cambridge), Mr John Skinner (RNOH), Miss Sarah Muirhead-Allwood (RNOH & The Hip Unit)
Stream: Clinical Fellowship
Topic: Lower Limbs / Biology (Hip)
Status: Completed

My three research questions were:
1) Can the association of low CD8+ve T cells and high metal ions be repeated in a larger cohort?

Findings:
This cohort of 96 hip resurfacing patients has replicated the association of reduced CD8+ve T cells and raised metal ion levels observed in our founder cohort (JBJS April 2006). This was specific to CD8+ve T cells.

2) Does bilateral hip resurfacing double the level of metal ions, and increase the effect on reducing the number of CD8+ve T cells?

Findings:
a) Whole blood cobalt and chromium levels can be used to measure in vivo wear rates, with bilateral MoM patients having 1.5 times the level of cobalt and chromium in whole blood when compared to our unilateral MoM cohort. Our new methods of measuring metal nanoparticles allow measurement of the effect of prosthesis parameters (either patient or surgeon dependent) on quantification of in vivo wear rates.

b) This cohort of 19 bilateral hip resurfacing patients has replicated the association of reduced CD8+ve T cells and raised metal ion levels observed in our founder cohort (JBJS April 2006).

3) What is the effect of metal ions on lymphocyte function?

Findings:
The immunological dysfunction, suggested by the reduced percentage of CD69 on CD8+ve T cells of patients with MoM THR, may determine in which body compartment T cells are located.

Dissemination of Research Findings
British Orthopaedic Research Society, Southampton 2006
BOA, International Bristol meeting “The Biological Effects of Metal Ions from Hip Replacements”
American Academy of Orthopaedic Surgeons, San Diego 2007
EFORT, Florence, May 2007
“Joined at the Hip” Institute of Mechanical Engineers, London April 2007
Acknowledgements
Professor Strauss (Immunologist, Royal Free Hospital)
Professor Marsh (Royal National Orthopaedic Hospital, Stanmore)
Professor Ferguson-Pell (Royal National Orthopaedic Hospital, Stanmore)
Professor Feldmann (The Kennedy Institute, Imperial College)
Professor Cobb (Imperial College)

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