| Mark Bloomfield addresses the latest BMJ article in UK |
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Re:
Not all that’s new and shiny is good for healthcareMark Bloomfield, MD's response on December 30, 2011 Problem is, if no innovation at all is tried, how do we make progress? McMinn was way more responsible than most innovators and went to great lengths to iron out any 'bugs' in the BHR before he released it to open market. He was so strict in the beginning, you HAD to go and see him in Birmingham, watch & assist before the company would allow you to use the BHR. Others, such as the originators of the ASR / De Puy, were much less rigorous. In this respect, De Puy has form: read about the Charite disc, Hylamer polyethylene. Then again almost all the large implant manufacturers have a skeleton or 2 in the closet..........
Not just ortho implants. Seen the fuss
over the French breast implants? Does this mean we stop all of them?
Despite what the article says, we know
FOR A FACT, that metal on 'traditional' polythene implants are reliable
in the young patient to begin with, but almost all will need revision
for aseptic loosening if they remain active and live long enough. Worse,
for the young patient the traditional advice was to limit activity and
slow down to place less stress on the bearing. No active sports at all!
Devastating for a young patient and not surprisingly when followed with
confidential questionnaires/ covert filming, almost all ignored the
'advice'. If there were no problems with metal on poly, no one would be
attempting other bearing couples! It is the vexatious question of who is
young and who is active that bedevils the metal/poly hip debate. In the
elderly: no question that metal/poly an excellent choice.
Enter ceramic/ceramic. More early
revisions, but generally seen as 'better' than metal on poly because
less wear. So if you are young, survive the initial ceramic/ceramic
problems, you do better in the long run than with metal/poly. But the
early failures make the overall results look bad. Depends how critical
you are. Late problems with ceramic/ceramic include fracture of head or
liner, squeaking [loud & embarassing] plus no 'shock absorption'.
MOM or metal/poly both have some 'give'.
So ceramic/ceramic a good compromise,
but not perfect. Ceramic must be made well to avoid fracture, and we now
have many more years experience of ceramic manufacture than most MOM.
Read about the failure of the St Gobain ceramic heads if you want
another scare story.
MOM depends heavily on three things: 1.
The quality of metallurgy & manufacture 2. The diameter of the
bearing. The bigger the better. So males do better than females [bigger
hips]. 3. The orientation of components by the surgeon. Lesser factors
are whether there is a secure trunion [junction] between the stem and
the MOM head. In resurfacing, there is no stem so there is no trunion.
Resurfacing does however carry the additional risk of fracture of the
bone below the implant. There is a rarer problem of adverse metal ion
reaction even in the presence of low metal ion levels. No solution for
this, and difficult to predict who will have it.
The article posted is lumping together
all MOM, which will give the impression: all MOM is bad. Not true.
McMinn et al in Birmingham are seeing
some, but not anything like, the same level of MOM problems being
reported elsewhere. There are 3 possible explanations:
-McMinn et al are dissembling or
deluding themselves.
-McMinn et al are not looking for the
problems, therefore unaware.
-McMinn et al are better surgeons,
using a better implant and have more experience than others.
No comment on which I believe!
In summary, MOM is riskier IN THE
BEGINNING, but if you have been given a good implant by a good surgeon,
and you survive the intial problems, a good MOM will probably last
longer than anything else. If it is a resurfacing MOM, it will feel more
natural, your surgeon will not wince when you say you ski on it.
Too many MOM hips are being taken out
to 'treat' a high blood metal ion level(s). There must be high levels
PLUS something else. Problem is the adverse publicity is making many
nervous and this exaggerates quite minor symptoms. And the really bad
implants / poor surgery / poor patient choice make things seem much
worse.
Happy New Year
Mark.
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