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Feature Medical Devices

How safe are metal-on-metal hip implants?

BMJ 2012; 344 doi: (Published 28 February 2012) Cite this as: BMJ 2012;344:e1410

Re: How safe are metal-on-metal hip implants?

After reading your article, it would be hard to believe the National Joint Registry graph of mortality following hip surgery (Figure 1). This data from over 700,000 patients suggests that hip resurfacing (HRA) has a significantly protective effect, while cemented hip replacement (THA) may have a negative effect on patients life expectancy. At the AAOS meeting mentioned in your article, this data was presented, with standardized mortality rates calculated. HRA does indeed have a real protective effect on life expectancy compared to THA, while a cemented hip does have a small but definitely deleterious effect. In that same session, we showed that resurfacing allows patients to return to high levels of activity in a way that even the best replacement cannot (Figure 2).

Hip resurfacing, while also a metal on metal articulation, is the safest operation in terms of life expectancy, and provides the highest level of function. If performed accurately, using a reputable device, the chances of any significant complications is very low, and serial blood tests are non-contributory. For those unfortunate people with a large diameter metal on metal THA with complex metallurgy, life is less simple. They need surveillance and may need revision.
This message should not be confused with hip resurfacing, which remains a safe option for active adults interested in life expectancy and quality of life, despite being a metal on metal bearing.

Competing interests: No competing interests

29 February 2012
Justin P Cobb
Orthopaedic Surgeon
Imperial College
St Dunstans Road, London W6 8RF