Outcomes following metal-on-metal hip revision have improved but could get even better, new study finds

A new study has found that outcomes following metal-on-metal hip revision surgery performed for abnormal reactions to metal have improved since the initial reports were published over five years ago, and are now similar to the outcomes in patients with other types of hip replacement undergoing revision surgery. The observed differences are in part due to increased surgical experience, researchers at the University of Oxford have suggested. However, the researchers proposed that surgeons had the potential to improve outcomes even further.

Approximately 1.5 million patients worldwide have received metal-on-metal hip replacements for painful arthritis. Abnormal reactions to metal can develop which may cause surrounding tissue damage. Many patients with these reactions require further operations, known as revision surgery. This is concerning as most patients who received this type of hip replacement are young and active. Therefore, poor results after these further operations would have a significant impact on a patient’s quality of life.

The biggest study in the world of its kind, published today (Monday 3 July 2017), used National Joint Registry data on 2,535 metal-on-metal hip replacement patients undergoing revision surgery performed for abnormal reactions to metal (also known as adverse reactions to metal debris – ARMD). The study, funded by Arthritis Research UK and the Orthopaedics Trust, was carried out by researchers based at the University of Oxford.

The research team also identified some factors that the surgeon can modify during revision surgery, which could potentially improve the outcomes for patients further. These factors specifically related to which of the original metal-on-metal hip components were removed by the surgeon, and which material the surgeon used for the articulation at the revision procedure. These latest findings are important as surgeons have currently received very little guidance about how best to treat these patients.

On the study’s findings, one of the authors, Mr Gulraj Matharu, commented:

“Early studies in this area highlighted catastrophic short-term outcomes for patients undergoing revision for abnormal reactions to metal, with up to one third of patients requiring further surgery known as re-revision. Therefore, it is encouraging to observe substantially improved outcomes following hip revision surgery performed for abnormal reactions to metal.  This is positive news as there are still many patients who have metal-on-metal hip replacements that may require revision surgery in the future.

“It is important that surgeons have robust information concerning the expected outcomes of this type of surgery in order to appropriately discuss potential risks with patients.  The findings from our study should help support this dialogue between surgeons and patients.

“Additionally, our findings identified risk factors associated with a poor outcome but which surgeons could actually modify during the revision procedure. Surgeons should therefore be mindful of these when making decisions regarding the type of hip reconstruction to perform. Doing so may help to further reduce the rate of subsequent failure following ARMD revision, which would be beneficial to our patients.”

Dr Stephen Simpson, director of research and programmes at Arthritis Research UK; comments:

“This study will be welcome news to the 56,000 people living with metal-on-metal hip replacements in the UK.  This research could help the small percentage of those patients who may need to undergo revision surgery, by not only assisting in decision making but also by improving the outcomes of the surgery through advice for surgeons.

“There would seem to be real value in reviewing and carefully considering the recommendations made within this study by healthcare professionals.”

The findings have been published in the Bone and Joint Journal. The study was also selected as part of a prestigious ‘Game Changers’ session at the American Academy of Orthopaedic Surgeons (AAOS) annual meeting earlier this year.

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