Practice NIHR Signals More than 50% of hip replacements seem to last 25 years

Why was this study needed?

Total hip replacement is a common surgical procedure, where a damaged hip joint is replaced with an artificial one. Several components are used, which can be made of different materials, with various ways of fixing them in place.

In 2017 there were 96 717 primary procedures carried out in England, Wales, and Northern Ireland. In the same year, 8589 hip revision procedures were done. These are further operations, carried out when the artificial joint components wear out, loosen, or break. Revision procedures may not be as effective at relieving pain and improving function, and often fail more quickly.

The average age of a patient receiving a replacement in the UK in 2017 was 69 years. Many people, when told they need a hip replacement, ask how long it will last. As average life expectancy increases, this question becomes more relevant. But there has been little good quality long term evidence. This study aimed to fill that gap.

What did the study do?

This systematic review and meta-analysis included 44 case series that reported long term outcomes of 13 212 hip replacement procedures. The authors also carried out a meta-analysis of data taken from the national joint replacement registries of Australia and Finland. These provided 215 676 procedures, with outcomes at 15, 20, and 25 years.

The quality of the published case series was low and it isn’t clear how generalisable the results of this study are. Only the Finnish registry had follow-up data at 20 and 25 years, and because the study draws on historical data. The metal, ceramic, and plastic components used in the underlying case series and registries are not all used in the UK currently.

What did it find?

Data from the case series were more prone to selection bias, but showed:

● After 15 years, 85.7% of hip replacements were intact (95% confidence interval 85.0 to 86.5; 12 case series, 5792 hips)

● After 20 years, 78.8% were intact (77.8 to 79.9; 20 series, 7192 hips)

● After 25 years, 77.6% were still intact (76.0 to 79.2; 8 series, 4617 hips).

Data from the registries had more patients followed up for longer and were less prone to selection bias. The data showed a different pattern and were probably more reliable for estimating the long term outcomes than the case series:

● After 15 years, 89.4% of hip replacements had survived (95% confidence interval 89.2 to 89.6; 215 676 hips from both the Australian and Finnish registries)

● After 20 years, 70.2% were intact (69.7 to 70.7; 73 057 hips from the Finnish registry)

● After 25 years, 57.9% were still intact (57.1 to 58.7; 51 359 hips from the Finnish registry).

What does current guidance say on this issue?

NICE guidance published in 2014 recommends hip replacement as a treatment option for end stage arthritis of the hip, but only if the component parts have rates (or projected rates) of revision of 5% or less at 10 years.

NICE doesn’t recommend a particular type of implant or component parts. It says that a patient’s age, activity levels, medical history, and the surgeon’s preferences and experience of using a particular type of implant should be taken into consideration.

What are the implications?

The results from the registry data are likely to be more realistic and reliable than the case series data because of the larger number of patients involved and the lower risk of selection bias.

Based on those figures, patients and surgeons can expect a hip replacement to last 25 years in more than half of all cases. Longer lasting components will reduce the need for hip revision procedures.

However, the implications of this study for UK practice are difficult to determine, given that UK data were not included. Long term data of the hip replacement components commonly used in the UK are available from the UK National Joint Registry.