| Peter Kay Response to Metal Ion Level Test for MOM in UK after FDA update 1/2013
I think overall, from the
U.K. perspective, metal-on-metal has been a real
problem. (For) most surgeons in the United
Kingdom, our usage of metal-on-metal hip
replacements has dwindled to almost nothing
because we cannot really find any advantage. The
patients do not do any better in terms of
function. There is some evidence the patient’s
reported pain levels are higher anyway and the
revision rate is higher, so it is not adding
much value.
In terms of
metal-on-metal, we (Medicines and Healthcare
products Regulatory Agency) have gone a little
bit further than the FDA because we also
recommend having a metal ion level test. It is
very hard to find a metal ion level where you
can say whether patients are likely to run into
problems, but one of the reasons we chose to go
down that route was that the medical literature
is not absolutely clear on whether aseptic
lymphocytic vasculitis associated lesion
reaction is a hypersensitivity reaction or just
a reaction to high metal ion levels. Most
patients will have a reaction if the level is
quite high. So we chose this level of 7 parts
per billion (ppb) for both cobalt and chrome. If
you have a level of 7 ppb or above, chances are
a fair number of people so far that have
problems have levels of that or above that. So,
that’s the sort of level where you start to feel
more worried. If it’s below 7, what we have
discovered is that low levels are rarely
associated with a problem, especially levels
below 3 ppb.
The difficulty is, the
patients who are anxious seem to develop some of
the symptoms that are put down as being due to
high metal levels. They don’t feel right; maybe
their eyes aren’t good; there is a buzzing in
their ears. And it is very difficult to reassure
that sort of patient. So we have gone a little
bit further to suggest that there may be a place
for doing a metal ion level test. Not that the
metal ion level means you should revise at a
particular level, but at a low level we feel we
can reassure a patient, and at a higher level we
think that can be a sign that things might be
going the wrong way.
Peter R. Kay, FRCS
Past president, British
Orthopaedic Association
Consultant orthopaedic surgeon
Wrightington Hospital
Wigan, England |
