People whose index finger is shorter than their ring finger are at higher risk of osteoarthritis, a new University of Nottingham study has found.
A study of more than 2,000 people, published in the journal Arthritis and Rheumatism, suggests that people whose index finger is shorter than their ring finger are up to twice as likely to suffer from the condition, which is the most common form of arthritis.
Index to ring finger length ratio (referred to as 2D:4D) is a trait known for its differences between the sexes. Men typically have shorter second than fourth digits; in women, these fingers tend to be about equal in length. Smaller 2D:4D ratios have intriguing hormonal connections, including higher prenatal testosterone levels, lower oestrogen concentrations, and higher sperm counts. Reduction in this ratio has also been linked to athletic and sexual prowess.
Whether this trait affects the risk of osteoarthritis (OA), the most common form of arthritis that may associate with both physical activity and oestrogen deficiency, has not been examined – until now.
Researchers at The University of Nottingham conducted a case-control study to assess the relationship between the 2D: 4D ratio and the risk of knee and hip OA. Their findings suggest that having a relatively long ring finger to index finger ratio raises the risk for developing OA of the knee, independent of other risk factors and particularly among women.
Professor Michael Doherty, lead researcher, said: “The 2D:4D length ratio appears to be a new risk factor for the development of OA. Specifically, women with the ‘male’ pattern of 2D:4D length ratio – that is, ring finger relatively longer than the index finger – are more likely to develop knee OA.”
As the first study to examine the relationship between 2D:4D length ratio and OA, it also raises questions. “The underlying mechanism of the risk is unclear,” Professor Doherty stressed, “and merits further exploration.”
Source: University of Nottingham, UK