New research has a possible reason for why British people are more likely to develop hip arthritis than Chinese people.
The results provide new insights into the most common type of arthritis in the UK, and who is most at risk of developing it in older age.
The study was undertaken through a Wellcome Trust funded collaboration led by the University of Bristol. Southampton’s Prof Nicholas Harvey contributed to the research.
It has been published in the journal Osteoarthritis and Cartilage.
Stiff and painful joints
Osteoarthritis is a condition that causes joints to become painful and stiff. The protective cartilage on the end of the bone breaks down, causing pain, swelling and problems moving the joint. Bony growths can develop, and the area can become swollen and red.
Hip osteoarthritis is a significant cause of pain, disability, and societal cost in older individuals. Hip shape is an important risk factor for its development.
White British people are more likely to develop the condition than Chinese. This study aimed to determine whether this was due to differences in hip shape.
The researchers used a variety of X-ray-based methods. They compared the hips of over 39,000 White British people in the UK Biobank against almost 6,000 people in the Chinese Shanghai Changfeng cohort. The average age of participants was 63 years.
Different hip shapes
Hip osteoarthritis was considerably less common in the Chinese cohort, for both men and women. Only 2.2% of the women in the Chinese cohort developed the condition, compared to 13% in the British cohort. For men, 12% developed it in the Chinese cohort, whereas in the British cohort it was 25%.
The researchers noted various differences in participants’ bone shapes in each cohort. Overall, participants in the Chinese cohort had a wider femoral head, the ‘ball’ of the thigh bone that fits into the hip socket. Yet the ‘neck’ of the thigh bone was narrower compared to the British cohort.
They found more British men (6.3%) than Chinese men (16.5%) had cam morphology, a bony lump on the ball of the thigh bone, at the join with the socket. It is rarely seen in women.
Prof Harvey is a Professor of Rheumatology and Clinical Epidemiology at the University of Southampton, and Director of the University’s MRC Lifecourse Epidemiology Centre. He is part of the NIHR Southampton Biomedical Research Centre.
“While it was previously known that White British people are more likely to get hip osteoarthritis than Chinese individuals, the reason for this has not been well understood,” he says.
“Through this collaborative study across two international datasets, we have identified bone characteristics that may help to explain these ethnic differences in the development and progression of hip osteoarthritis.”
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