Mark Bloomfield addresses the latest BMJ article in UK
Not all that’s new and shiny is good for healthcare
Mark 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