Thumb Hypoplasia and Aplasia (Small or Missing Thumb)

What is thumb hypoplasia? 

Thumb hypoplasia, also known as hypoplastic thumb, is a condition in which a child’s thumb is smaller than normal. Thumb aplasia is a condition in which the thumb is completely absent. Thumb hypoplasia or aplasia often happen in children with radial longitudinal deficiency. These conditions can be genetic and may be symptoms of conditions that also involve other organ systems in the body.

How are thumb hypoplasia and thumb aplasia diagnosed?

Your baby’s doctor will usually notice thumb hypoplasia or thumb aplasia during your baby’s first exam as a newborn. If the doctor suspects thumb hypoplasia or thumb aplasia, he or she will look for other differences that may be associated with these conditions. X-rays may also help the doctor learn more about the structure of your baby’s thumb.

How are thumb hypoplasia and thumb aplasia treated?

Treatment depends on the severity of thumb hypoplasia or aplasia. We work with each patient and family to discuss all the options and identify the best one for every patient’s unique needs. Sometimes, the thumb may be smaller than normal but the child is able to function normally, in which case no surgery is needed. If the thumb is weak or can’t move properly, thumb reconstruction surgery may be recommended, in addition to occupational therapy.

If the thumb hypoplasia is very severe or no thumb is present (thumb aplasia), index finger pollicization surgery may be recommended. In this surgery, a functional thumb is created by moving another finger to the thumb position. Occupational therapy is essential to ensure success after any surgery.