Hitchhiker's Thumb

The Hitchhiker's Thumb consists of (1):

  • Oval and hypoplastic first metacarpal.
  • Abducted proximally positioned thumb.
  • Low set first digit.
  • Etiology:
    1. Skeletal dysplasia  -
    2. Isolated and familial (15%).
    3. Trisomy 18 (30%) and trisomy 13.
    4. Fetal akinesia and arthrogryposis.
    5. Prolonged oligohydramnios.
    6. Limb-body wall complex (32%).
    7. Spina-bifida.

 

Clasped Thumb

Marked flexion of the metacarpophalangeal joint and adduction into the palm.

  • Rare.
  • Males > Females.
  • Usually no other associated anomalies are present.

 

 

 

REFERENCES
  1. Bronshtein M, Stahl S, Zimmer EZ. Transvaginal sonographic diagnosis of fetal finger abnormalities in early gestation. J Ultrasound Med 1995;14:591-595.