Sunday, January 29, 2012

Another Hypothesis on the cause of Pseudotumors associated with MoM hips

I thought this article was really interesting as it concludes that these pseudotumors are NOT associated with any of the common reasons (high metal levels in the blood, bad postioniong of the hip prothesis or increased wear.)
Clin Orthop Relat Res. 2011 Dec 17. [Epub ahead of print]

Pseudotumors Are Common in Well-positioned Low-wearing Metal-on-Metal Hips.


Department of Musculoskeletal Surgery, Imperial College London, London, SW7 2AZ, UK,



Pseudotumors are sterile inflammatory lesions found in the soft tissues surrounding metal-on-metal (MOM) and metal-on-polyethylene hip arthroplasties. In patients with MOM hip arthroplasties, pseudotumors are thought to represent an adverse reaction to metal wear debris. However, the pathogenesis of these lesions remains unclear. Currently, there is inconsistent evidence regarding the influence of adverse cup position and increased wear in the formation of pseudotumors.


We therefore determined whether pseudotumor formation was associated with (1) adverse cup position, (2) raised metal ion levels, and (3) increased wear rates of the retrieved components.


We retrospectively reviewed all 352 patients for whom we had retrieved specimens from revisions of a current-generation MOM hip prosthesis between February 2008 and September 2010; of these, 105 met our inclusion criteria. We used multivariate logistic regression analysis to compare acetabular orientation, metal ion levels before revision, and component wear rates between patients with (n = 72) and without (n = 33) pseudotumors, according to findings on metal artifact reduction sequence MRI.


The proportion of patients demonstrating evidence of a pseudotumor in well-positioned hips was similar to those with adverse cup positions (67% and 66%, respectively). Patients revised with pseudotumors had similar whole-blood metal ion levels and component wear rates to those who were not revised.


Pseudotumors were not associated with increased wear or metal ion levels, suggesting patient susceptibility is likely to be more important

1 comment:

  1. It would be interesting to know who funded this study. The timing seems to favor MOM manufacturers doesn't it? If it were facts, it would have been brought up years ago. I'm not saying, I'm just sayin.