Hypoplastic Thumb

The milder forms of hypoplastic thumb can be reconstructed by means of tendon transfers to restore function to the thumb.

However, in the more severe forms of hypoplastic thumbs in which the thumb is either very rudimentary or sometimes totally absent, are best reconstructed by transposing the index finger into the thumb position and by a process called pollicization of the index finger. In this manner, the index finger is foreshortened and swung into the thumb position with the webspace being recreated by rotation flaps. This three-fingered hand, now with a normally positioned thumb, generally functions very well and has a natural appearance.

Also, a hypoplastic thumb and radial deficiency may occur with certain blood disorders. In the thrombocytopenia absent radius syndrome (TAR syndrome) there is a deficiency of platelets and a resulting blood coagulation disorder. The thumb is generally well formed, but the radius is absent. Fanconi's aplastic anemia can also occur in association with thumb and radius deficiencies. In this case, the blood abnormality may become manifest only some years after birth.