Hitchhiker's thumb is an inherited trait where the distal phalange of the thumb can bend backwards beyond the normal range of motion, up to an angle of 90ð. The trait can be present on one or both thumbs. It is typically painless and benign, but can sometimes be associated with genetic diseases such as hypermobility spectrum disorders.
The trait is named hitchhiker's thumb as it resembles the hand gesture used to hitch a ride on the side of a road.
Hitchhiker's thumb involves having a thumb with a distal phalange that is able to bend backwards beyond the normal range of motion (50ð), up to an angle of 90ð. Some people with hitchhiker's thumb also have a Z-shaped deformity, named after the appearance of this deformity. The trait in itself is usually painless and does not normally affect usage of the hands.
Hitchhiker's thumb is a genetic trait and is inherited in an autosomal recessive manner. It may sometimes be associated with genetic diseases, including:
Hitchhiker's thumbs affect 24âÂÂ36% of the U.S. population.