total hip replacements

The National Institute for Health Research (NIHR) is the biggest clinical research funder in Europe and has recently published results of a study looking at the effectiveness of a range of prosthetic implants used in patients who have undergone total hip replacement surgery.

This research is important because total hip replacements are extensively carried out in England and Wales, with almost 100,000 being fitted in 2017.

The research dataset was huge; the team assessed “more than 1 million individual patient-records from national joint registries in the UK and Sweden, countries with similar publicly funded health services.” They looked at how total hip replacements fared for men and women and they looked at the revision rate for all cases (which is the requirement for follow up surgery following the initial operation).

All the different types of prosthetic implant were assessed, of which there are a variety of different types of implants available:

  • Metal on polyethylene – this is the most frequently used implant type and its origins date back to the middle of the twentieth century. It has a long and successful history but over time the polyethylene part can become worn and begin to wear down.
  • Other combinations include ceramic-on-polyethylene, metal-on-metal and ceramic-on-ceramic. These are newer evolutions and cost more to produce. There are also different ways of fixing these newer implants to the existing bone, which can have an impact on their overall effectiveness.

The results are interesting, concluding that there is no evidence of benefit with new more expensive implants over older implants. This obviously has a cost implication too, as many of the newer implants represent a more expensive option.

The implant that fared most positively in the research was actually the cheapest one available, although this finding was only conclusive in the over 65 age bracket. The “small-head cemented metal-on-polyethylene implants” cost around £750, has the lowest amount of follow up surgery and is currently used in around one third of total hip replacements in the UK.

In second place, the “small-head cemented ceramic-on-polyethylene implants were most cost-effective in men and women younger than 65 years ” although the report authors stress that there were some factors that they couldn’t assess comprehensively in this age group, such as predicting the revision rate that might be seen in the future.

What does that mean for patients awaiting total hip replacements?

There are many different factors that affect which type of implant is chosen for each patient. Factors include biological and lifestyle elements, such as age, weight, gender and level of activity (currently and desired). Surgeons often have a preference for the type of implant they choose to use, based on their own research and experience of fitting them.

If it isn’t broken, don’t fix it

What is most interesting is that in this case, newer doesn’t necessarily mean better, and more expensive doesn’t equate to necessarily being better either. The long-standing, older-style implants still offer a sustainable, effective solution for those of use whose joints are deteriorating and are in need of a prosthetic implant.