2D:4D finger length ratio and radiographic hand osteoarthritis.

To evaluate the association between the index and ring finger's (2D:4D) length ratio with the prevalence and severity of radiographic hand osteoarthritis (OA). A population-based sample included 802 males (mean age 46.98 ± 17.10 years) and 738 females (mean age 48.65 ± 16.62 years) who had participated in a Chuvashian skeletal aging study. Age, sex, basic demographics, anthropometric data and X-rays of both hands were acquired. Each hand was visually classified on X-ray as either type 1-index finger longer than the ring finger; type 2-index and ring finger equal in length; or type 3-index finger shorter than the ring finger. Hand OA was defined by the number of affected joints (Kellgren-Lawrence score ≥ 2) in both hands and the sum total of Kellgren-Lawrence scores (total OA score). After comparing the OA variables of individuals with different finger length ratio types (after adjustment for age and BMI) significant differences were found only in females between finger ratio types of the right hand in a number of affected joints (F = 3.153, p = 0.043) and finger ratio types of the left (F = 3.330, p = 0.036) and right (F = 2.397, p = 0.047) hands of the total OA score. Females with type 3 ratios had the highest adjusted values of hand OA parameters. We found that finger length ratios are associated with hand OA parameters. Females with a type 3 finger length pattern showed significantly higher hand OA values than those with types 1 and 2.