Using finger length patterns to predict susceptibility to osteoarthritis and chronic joint pain

This study examined whether there is a link between the length of patients fingers and chronic pain or osteoarthritis (the most common form of arthritis; it occurs when the protective cartilage covering the bone gets worn away).

Finger length pattern (FLP; or digit ratio) refers to the ratio between the second digit (the index finger) and the fourth digit (the ring finger). FLP can be classified into 3 types: type 1 (the ring finger is shorter than the index finger), type 2 (both fingers are the same length) or type 3 (the ring finger is longer than the index finger).

Research suggests that type 3 FLP is due to higher exposure to male sex hormones before birth. This has led to FLP being used as a marker for sexually dimorphic traits (traits that are different between males and females). As both chronic pain and osteoarthritis are considered to be sexually dimorphic diseases it is possible that FLP could be useful for predicting the risk of these conditions.

The authors analyzed 4,884 participants to determine if any links exist between FLP and osteoarthritis or chronic joint pain. The participants were examined for evidence of osteoarthritis (knee, hip and hand), symptomatic osteoarthritis (knee, hip and hand) and chronic joint pain.

The risk of hand osteoarthritis increased by 64% in patients with type 3 FLP. However, type 3 FLP was not associated with an increased risk for knee or hip osteoarthritis.

The risk of having chronic joint pain was also associated with FLP. The risk of experiencing chronic joint pain was increased by 18% in patients with type 3 FLP. The risk of experiencing chronic joint pain in more than 2 joints was increased by 41% in patients with type 3 FLP.

The authors concluded that type 3 finger length patterns were associated with chronic joint pain and osteoarthritis of the hand. However, there was no link between finger length pattern and radiographic osteoarthritis of the knee