Hitchhiker's thumb
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 names | Distal hyperextensibility of the thumb, thumb hypermobility, Z-shaped deformity,[1] duck-bill thumb [2] |
 | |
| Example of bilateral hitchhiker's thumb | |
| Specialty | Medical genetics |
| Symptoms | A thumb that can bend backwards at more than a 90° degree angle |
| Complications | If it presents as an isolated trait, none |
| Duration | Life-long |
| Causes | May either present as an isolated trait, or be a symptom of a condition such as a hypermobility spectrum disorder[medical citation needed] |
| Risk factors | Family history |
| Frequency | 24–36% 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[edit]
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.
Causes[edit]
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[edit]
It does not need treatment.
Incidence[edit]
Hitchhiker's thumbs affect 24–36% of the U.S. population.[3]
See also[edit]
- Hypermobility (joints)
- Ligamentous laxity
- Hypermobility spectrum disorder
- Ehlers–Danlos syndromes
- Diastrophic dysplasia
References[edit]
- ^ "What Is Hitchhiker's Thumb?". WebMD.
- ^ Shetty, Aditya. "Hitchhiker thumb deformity | Radiology Reference Article | Radiopaedia.org". Radiopaedia.
- ^ a b "Do you have the genetics for the Hitchhiker's Thumb?". Transformational Bioinformatics. May 9, 2019.
- ^ "What is Hitchhiker's Thumb? Inherited Traits and Body Quirks". www.brighthub.com. June 30, 2009.