National Joint Registry study finds disparities in hip or knee joint replacements for ethnic minorities

Researchers have found that the number of both hip and knee replacement operations for Black and Asian ethnic minorities are lower than expected when compared to Whites.

Over 640,000 patient records were examined in the first large-scale study of ethnicity and joint replacement in the UK, led by the University of Bristol using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR).

Published online (Friday 17 March, 2017) in Osteoarthritis and Cartilage, the journal of the Osteoarthritis Research Society International, researchers were able to show the recorded numbers compared to expected numbers of patients having first time hip or knee joint replacement by ethnicity. The findings highlighted that fewer than expected procedures amongst Black and Asian populations were taking place, with a far more significant difference for hip replacement procedures.

The study also showed gender differences with non-White men significantly less likely to receive a joint replacement compared to non-White women. The findings also reinforce existing research showing that patients from ethnic minority groups having either hip or knee replacement for osteoarthritis were more likely to be living in poorer areas.

Professor Ashley Blom, from the University of Bristol who led the team that undertook the study on behalf of the National Joint Registry, said:

There are many possible explanations for why ethnic minorities are undergoing fewer than expected joint replacement operations and it is likely a combination of different factors.

One possible explanation could be patient willingness to undergo surgery amongst the different ethnic groups examined. This is often shaped by cultural factors, doctor-patient communication, and even patient trust in the healthcare system. Secondly, osteoarthritis of the hip is slightly less common amongst Black and Asian people and this may partially explain the differences.

It is also interesting to note the gender differences in rates of knee replacement with Black and Asian males much less likely to undergo joint replacement than Black and Asian females. These initial observations require further investigation.

The study also investigated the differences in the types of implant (prosthesis) and operation method (fixation) used between the ethnic groups. Researchers noted that there was “a surprising difference” in the higher use of the more expensive uncemented hip prostheses for ethnic minority patients, in particular amongst black minority groups.

Concluding on the study’s findings, Professor Blom added:

Patients from an ethnic minority background are more likely to have their joint replacement at hospitals which are higher users of uncemented hips. This means that the hospital in which a patient is operated on is a major determinant of the differences in hip replacement fixation method, as large, urban hospitals tend to serve a greater proportion of ethnic minority patients.

The major strength of this analysis is the huge amount of data available as the NJR is the largest joint replacement registry in the world. Yet, at this stage we remain unclear as to the importance of each possible reason as to why there are such differences in the rates of joint replacement in different ethnic groups, and in the types of implant and fixation used. Whether this reflects differences in clinical need or unequal access to treatment requires further investigation.