clinical features

Last reviewed 01/2018

The clinical features of a congenital hypoplastic thumb are very variable depending on the severity of the phenotype. At its most severe form, an absent thumb is noted from birth. At the other extreme, very mild forms of thumb hypoplasia may go unnoticed into adulthood. Spanning this spectrum, the following features should be noted:

• thumb:
  • can show bilateral features
  • smaller than expected
  • narrowed first web space
  • absence of voluntary movement at the IPJ in the child
  • amount of thumb opposition
  • unstable CMCJ demonstrated by stressing the joint
• examination of whole upper limb for:
  • associated anomalies eg length of radius with radial dysplasia, pectoral development with Poland's Syndrome
  • stability of more proximal joints
  • status of ipsilateral index finger if pollicisation is considered
• functional ability: watch the child playing with toys, writing or holding a cup; has the child already developed a 'cigarette grip' between the index and middle fingers for most tasks
• examination for systemic anomalies eg heart murmurs with Holt-Oram syndrome, vertebral anomalies with VATER association
• parental hand examination for familial inheritance