The DePuy ASR recall; which other devices will follow?

FOR FURTHER INFORMATION AND RELATED BLOG ENTRIES VISIT OUR DEDICATED DePUY HIP IMPLANT RECALL PAGE

In the wake of the DePuy ASR recall which was issued in August 2010, concerns are mounting regarding the safety of metal-on-metal prosthetic hip devices in general.  As the US Food and Drug Administration has stated on the website which it has specially dedicated to the issue:  “[a]ll artificial hip replacement systems have risks related to implant or material wear.  Metal-on-metal hip (MoM) replacement systems have unique risks in addition to the general risks of all hip implant systems.”

While the FDA is at present of the view that there is no evidence to support the need for checking metal ion levels in the blood or special imaging if patients with MoM hip implants (other than ASRs) are not showing any adverse symptoms, it is recommending that asymptomatic patients with MoM hip implants continue to follow-up with their orthopaedic surgeon as a precaution.

On this side of the Atlantic, at the British Hip Society’s Annual Conference held in March 2011 early failure rates in large diameter MoM bearing total hip replacements was considered.  While there was a predominance of the DePuy ASR XL device, large diameter MoM devices from other manufacturers were also found to be appearing to present similar results.

The results which were presented showed a higher than anticipated early failure rate, ranging from a 21% revision rate at 4 years (potentially rising to 35% if all painful implants then recorded were ultimately to progress to revision) to 49% at 6 years for the ASR XL device.

Some of the reasons for this heightened failure rate were put forward at the meeting and particular concern was expressed regarding the trunnion at the ‘Morse’ taper where the large diameter metal head attaches to the stem due to the fact that several revised devices showed damage at this location.

Modes of failure varied from loosening of the acetabular component, loosening of the femoral component, or metal reaction with necrosis and soft tissue damage.

Based on the results presented, the Society cautioned that the use of large diameter MoM bearings in primary total hip replacements should be carefully considered and possibly avoided.

More recent investigations conducted in the UK have found further evidence of unacceptably high rates of failure in large diameter hybrid MoM replacements, with these increased rates being associated with a high incidence of adverse reaction to metal debris.

Females were found to be at an increased risk.  The presence of pain and radiographic changes were found to be significant predictors of failure, with those patients who required revision surgery also having significantly higher whole blood cobalt ion levels.

Of those explanted devices which were interrogated, wear was detected in the trunnion and corrosion was also observed in the stem.  This has raised concerns over the use of large heads on conventionally utilized 12/14 tapers.

While it is becoming increasingly evident that problems being experienced with MoM devices are not confined solely to DePuy ASR systems and that many other products may give rise to heightened risks of early failure, the Pinnacle system which was also developed by DePuy Orthopaedics has come under particular scrutiny.

Analysis of failed ex vivo 36mm MoM Pinnacle hips carried out by Dr Tom Joyce and others led to the conclusion that mechanical failure at the head/stem interface appears to be a critical factor in the development of adverse reactions following MoM total hip replacements.  Taper damage was also identified as another potential source of metallic debris alongside that which may originate from the articulating surfaces.

Litigation surrounding the Pinnacle has already built up a head of steam in the US:  more than 50 individual lawsuits have been consolidated into the DePuy Pinnacle multidistrict litigation case.  The multiple claimants in that litigation are alleging that in addition to debilitating pain and immobility, raised levels of chromium and cobalt are also a factor, with metal toxicity being observed in some individuals.

Time will tell whether the litigation surrounding MoM devices is confined to DePuy Corail, Pinnacle and ASR components or products manufactured by other companies will follow.

If you have been affected by the ASR hip implant recall or you believe that you have been affected by any other defective prosthetic device and you would like to arrange a free initial consultation with John McCarthy feel free to call him on 023 883 3348023 883 3348 or email him at john@mccarthy.ie to discuss your case in complete confidence and without commitment.

FOR FURTHER INFORMATION AND RELATED BLOG ENTRIES VISIT OUR DEDICATED DePUY HIP IMPLANT RECALL PAGE

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John specialises in personal injury and medical negligence claims. His practice focuses on high value compensation cases. He has extensive experience in this area of litigation for over 10 years. Read more