Absent thumb

The thumb is the most distinctive feature of the primates including humans, as the opposable thumb allows versatile function of the hand. However, the thumb may be rudimentary ( Hypoplasia of the thumb) or may be totally absent ( Aplasia of the thumb) in some individuals. This may occur as an isolated anomaly ( Birth defect) or it may be a feature associated with other issues like absence of the radius (See Radial Club Hand for more information) . children with Holt-Oram syndrome, Fanconi’s anemia or ring D chromosome abnormalities may also have an absent thumb. Absent or rudimentary thumb is rare , occurring in less than 1 in 1,00,000 live births.

Treatment : Management depends on the severity of the anomaly. The Blauth grading system is based on presence or absence of intrinsic (thenar) muscles, stability of the joint ( Called carpometacarpal joint) which gives stability to the thumb. In minor hypoplasia or Type l, no active treatment is required. in Type ll and Type lllA reconstruction and stabilization is likely to help. However, in more severe Types lllB & lV the limb bud needs to be sacrificed and a new thumb is made surgically from the index finger. This surgery is called Politicization. In type V, where there is a total absence of the thumb, Politicization is the optimal surgical option.

Politicization surgery needs to be performed at around the age of one year, when the brain learns to specifically use the thumb for fine motor skills. if performed later in life, the brain may not be able to adapt to use the new thumb in the best possible way.

If your near one is born with an absent thumb, please don not hesitate to share your concerns with us.