Thumb hypoplasia/aplasia

Thumb hypoplasia, also commonly called hypoplastic thumb, means that your child’s thumb is unusually small or underdeveloped. Thumb aplasia means that your child’s thumb is missing altogether.

In general, there are five types of thumb hypoplasia or aplasia:

• Your child’s thumb is slightly smaller than normal, but all of its structures — the bones, tendons, ligaments, muscles and joints — are normal.
• Your child’s thumb is small and there are often minor abnormalities in the tendons and muscles within the thumb.
  • The middle joint of the thumb is unstable, causing the thumb to wobble. The web space between the thumb and index finger is tight and restricts movement.
  • The bones of your child’s thumb are abnormally small.
• There are abnormalities in many of the thumb's muscles along with a range of problems in the joints of the thumb and an abnormal tight web space between the thumb and index finger.
• Your child’s thumb is "floating" with no bony support and is attached to the hand by only skin and soft tissue.
• Your child’s thumb is missing.

Partners in care

If your child has mild thumb hypoplasia, she may undergo a course of occupational therapy, which will help improve the function of the thumb. The Occupational Therapy Program at Children’s is dedicated to collaborating with you and your child’s doctor to provide the best possible care for your child.

Treatment programs are based on thorough evaluations and are always individualized to meet the needs of your child.