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Which primary total hip replacement?

A good question. In the UK, Murray and colleagues [1] have identified 62 different primary total hip replacements manufactured by 19 different companies. Half of these have been introduced in the last five years, and only 30% have any results published in peer-reviewed journals. Costs can range from £250 to £2000. The two cheapest implants have the longest follow up.

So what's the problem?

There are about 40,000 THRs carried out in the UK every year. The ideal is for the new joint to be put in and stay in without problems, but after 10 years about 10% of the joints do develop problems which necessitate a new operation and new joint. These revisions cost more, don't work as well or last as long as the primary THR. About 5,000 revision operations are done each year in the UK.

Long-term outcome becomes a major issue which determines overall cost and benefit. So much more so when devices are changed or improved.

What's the evidence

What evidence there is has been summarised in the review of all UK devices [1]. Five-year survival data were found for eight implants in peer-reviewed journal articles. For three there were ten-year survival results, for two 15-year survival results and for one 20-year survival results.

The two implants with more than 10-year results were the Charnley and Stanmore implants, which were amongst the cheapest.

Recommendations

In a thoughtful discussion, of interest to providers and purchasers, the authors make the following recommendations:
  • Group A implants would be the small group with published long-term results that would allow patients, surgeons and purchasers to be reasonably confident that the implant is safe and will give reliable and reproducible results.
  • Group B would include implants with good short-term published results, but in the transition to more formal EU directives on hip prostheses would include implants already available but with no published results. Surgeons may choose Group B implants for a variety of reasons, but it seems reasonable that purchasers and patients should be aware that there is uncertainty over their long-term reliability.
  • Group C would comprise new implants which should be subject to some form of clinical testing as well as laboratory wear testing before being available, as modern prediction techniques should weed out those at high risk of failure.

Reference:

  1. DW Murray, AJ Carr, CJ Bulstrode. Which primary total hip replacement? Journal of Bone and Joint Surgery 1995 77-B: 520-7.



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