Sunday, February 5, 2012

So what is the cause of these pseudotumors after the second revision? (part 2 of x in this series)

This is a follow up to the last post  On Friday, I posted a journal article which was published by some researchers at Oxford in 2008 who concluded, with a small patient sample, that bilateral masses developed in periprosthetic soft tissues following the second MoM arthroplasty  were characterised histologically by extensive coagulative necrosis, a heavy macrophage infiltrate and the presence of granulomas containing macrophages and giant cells. 

In further researching this issue, I found that some of the members of the first  research group  published a second article two years later seeming to question the results of their first study.

So my question is if these so called necrotic granulomatous pseudotumours as referred to in the first study are NOT a result of Type IV immune response to the metals, what are they in fact caused by?

Here is the second study which they published in 2010.  The one I published on Friday was published in 2008.

More tomorrow...I will look into this more later today.

J Orthop Res. 2010 Apr;28(4):444-50.

Lymphocyte proliferation responses in patients with pseudotumors following metal-on-metal hip resurfacing arthroplasty.


Nuffield Department of Orthopaedic Surgery, University of Oxford, Windmill Road, Oxford OX3 7LD, United Kingdom. ymkwon@partners.or


Locally destructive soft tissue pseudotumor has been reported in patients following metal-on-metal hip resurfacing arthroplasty (MoMHRA). A delayed hypersensitivity reaction type IV to nickel (Ni), chromium (Cr), or cobalt (Co) has been suggested to play a role in its aetiology. The aim of this study was to investigate the incidence and level of metal-induced systemic hypersensitivity in patients with MoMHRA, both with and without pseudotumor by measuring lymphocyte proliferation responses to metals. A total of 92 patients were investigated: (1) MoMHRA patients with pseudotumors (nine female, one male); (2) MoMHRA patients without pseudotumors (30 female, 30 male); and (3) age-matched control subjects without metal implants (9 female, 13 male). The venous blood samples were collected for serum Ni, Co, and Cr ion level measurements and lymphocyte transformation tests (LTT). A higher incidence and level of enhanced lymphocyte reactivity only to Ni was found in patients with MoMHRA compared to the patients without MoM implants, reflecting exposure and immune reactivity. However, lymphocyte reactivity to Co, Cr, and Ni did not significantly differ in patients with pseudotumors compared to those patients without pseudotumors. This suggests that systemic hypersensitivity type IV reactions, as measured by lymphocyte proliferation response to these metals, may not be the dominant biological reaction involved in the occurrence of the soft tissue pseudotumors.

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