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Hitchhiker's thumb

From Wikipedia, the free encyclopedia

Hitchhiker's thumb, also known as distal hyperextensibility of the thumb, is the condition of having a thumb that has a distal phalange that bends backwards in an angle of 90°. This condition is benign (when isolated) and does not cause pain or affect the thumb with the trait negatively.

Hitchhiker's thumb
Other namesDistal hyperextensibility of the thumb, thumb hypermobility, Z-shaped deformity,[1] duck-bill thumb [2]
Example of bilateral hitchhiker's thumb
SpecialtyMedical genetics
SymptomsA thumb that can bend backwards at more than a 90° degree angle
ComplicationsIf it presents as an isolated trait, none
DurationLife-long
CausesMay either present as an isolated trait, or be a symptom of a condition such as a hypermobility spectrum disorder[medical citation needed]
Risk factorsFamily history
Frequency24–36% of the U.S. population [3]

If a person has the genes for this condition, it might present bilaterally, unilaterally, or on none of the thumbs.

Signs and symptoms

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Symptoms vary among people with hitchhiker's thumbs, those who have it as an isolated trait are not affected by any symptoms, however, this trait is sometimes a symptom of other conditions, such as a hypermobility spectrum disorder.

The signs of this trait are having a thumb with a distal phalange that is able to bend backwards beyond the normal range of motion. Some people with hitchhiker's thumb also have a Z-shaped deformity, named after the appearance of this deformity, which is that of the letter Z.

Example of a z-shaped deformity in a hitchhiker's thumb

Causes

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The exact cause of isolated hitchhiker's thumb is not known, it is thought to be inherited in an autosomal recessive manner.[4]

However, this trait is often a symptom of an underlying condition, such as

Treatment

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It does not need treatment.

Incidence

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Hitchhiker's thumbs affect 24–36% of the U.S. population.[3]

See also

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References

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  1. ^ "What Is Hitchhiker's Thumb?". WebMD.
  2. ^ Shetty, Aditya. "Hitchhiker thumb deformity | Radiology Reference Article | Radiopaedia.org". Radiopaedia.
  3. ^ a b "Do you have the genetics for the Hitchhiker's Thumb?". Transformational Bioinformatics. May 9, 2019.
  4. ^ "What is Hitchhiker's Thumb? Inherited Traits and Body Quirks". www.brighthub.com. June 30, 2009.