Uncomfortable shoes might not be only to blame for bunions, as the foot condition could have a genetic link, according to a study.
The Framingham Foot Study has shown that bunions are highly heritable, making it the first study to do so. One of the most common foot disorders, bunions are painful bony swellings at the base of the big toe. They occur when the bones of the big toe start to turn inwards, pointing at the other toes.
Taking six years and measuring 1,370 people's feet, this study measured three generations of people living in Framingham, Massachusetts, USA. Accounting for age, sex and body mass index – the previously known risk factors – the authors showed that bunions and several other common toe deformities are highly heritable. This means that the likelihood of developing bunions can mostly be attributed to genetic differences.
'Our study is the largest investigation of the heritability of common foot disorders in older adults, confirming that bunions and lesser toe deformities are highly inheritable in Caucasian men and women', said Dr Marian Hannan from Hebrew SeniorLife and Harvard Medical School, who led the study. 'Knowing more about the pathway may ultimately lead to early prevention or early treatment'.
The authors suggest that inherited characteristics which inform the size and shape of the feet bones, or the muscles that control them, may contribute towards bunion susceptibility in later life.
Despite affecting around a fifth of adults (increasing to over a third in later life), the causes of bunions remain poorly understood. While ill-fitting shoes are often blamed, doctors now believe that these exacerbate the symptoms rather than causing them.
Richard Handford, of the UK's Society of Chiropodists and Podiatrists, told the BBC: 'This is what we tell our patients - as opposed to the myth that shoes cause bunions. It is something a person will have a predisposition to - but poor footwear will exacerbate it'.
As the study focused on those of European descent, further studies will be required to see whether the findings apply to other populations. The scientists plan to seek the gene variants related to these foot deformities.