What are congenital hand differences?

Congenital anomalies are hand or finger differences that are present at birth. Any type of difference in a newborn can become a challenge for the child as he or she grows. Hand differences can be particularly disabling when they are severe as the child learns to interact with the environment through use of his or her hands. Types of differences include extra fingers and thumbs, fused fingers, undergrowth or overgrowth of the hand, fingers and arm, and missing fingers and thumbs or bones of the arm. 

Early consultation with a hand surgeon is an important part of the treatment process. If reconstructive surgery is not possible, there are many types of prosthetic devices that can be used to increase function.

What are the types of congenital hand differences?

The classifications for hand differences vary. The following classifications have been accepted by the American Society for Surgery of the Hand. There are currently seven groups of differences of the hand:

Problems in Formation of the Parts

This occurs when parts of the body stop developing while the baby is in the womb. This causes either a complete absence of a body part, such as a hand, or a missing structure, such as part of an arm bone. In the case of a completely missing part, surgery is not performed. Instead, these children may receive a prosthetic device early in their childhood. Types of these classifications include:

• Radial clubhand. A radial clubhand is a difference in all of the tissues on the thumb side (radial side) of the forearm and hand. There may be shortening of the bone, a small thumb or absence of the thumb. Differences of the wrist are usually operated on at about 6 months of age.
• Ulnar clubhand. Ulnar clubhands are less common than radial clubhands. The ulnar bone (the bone in the forearm on the side of the small finger) may be underdeveloped or it may be completely absent.

Failure of Parts of the Hand to Separate

With this type of difference, the bones or tissues of the hand fail to separate in the womb. The most common type of this classification is syndactyly, which is when two or more fingers are fused together. There is a familial tendency to develop this difference. If the fingers are completely fused together, it is considered complete. There are two types of syndactyly:

• Simple syndactyly involves fusion between only the soft tissues of the fingers
• Complex syndactyly involves fusion between the bones and fingernails

Pediatric Trigger Thumb

Pediatric trigger thumb is when the thumb is unable to fully straighten (extend) and often gets stuck in the bent (flexed) position. The cause of the triggering is due to thickening of the tendon, which “pops” as it slides through the protective sheath that covers the tendon. Some of these cases improve on their own. Surgery is usually not performed until the second year of life, but preferably before age 3.

Duplication of Fingers

Duplication of fingers is also known as polydactyly. The small finger is the one most often affected.

Undergrowth of Fingers

Underdeveloped fingers or thumbs are associated with many congenital hand differences. Surgical treatment is not always required to correct these differences. Underdeveloped fingers may include the following:

• The finger is small
• Muscles are missing
• Bones are underdeveloped or missing
• A finger is completely absent

Overgrowth of Fingers

Overgrowth of fingers, also known as macrodactyly, causes an abnormally large finger. The hand and forearm may also be involved. In this rare condition, all parts of the finger (or thumb) are affected; however, in most cases, only one finger is affected (usually the index finger). Surgical treatment of this condition is complex and the outcomes may be unsatisfactory. Sometimes, amputation of the enlarged finger is recommended.

Congenital Constriction Band Syndrome

This occurs when a tight tissue band forms around a finger, arm or leg, causing problems that can affect blood flow and growth. Ring constrictions are congenital (present at birth). This condition may be associated with other birth differences, such as clubfoot, cleft lip or cleft palate. The cause of constriction rings is unknown, but some theories suggest they are due to a piece of the amniotic membrane breaking off and wrapping around the body part. Treatment usually involves release of the tight bands and reconstruction of the finger, but it depends on the severity.

Other Generalized Problems Regarding the Skeletal System

The problems in this group are rare and complex.

Treatment for Congenital Hand Differences

Specific treatment for congenital hand differences is determined by your child’s doctor based on:

• The child’s age, overall health and medical history
• Extent of the condition
• Cause of the condition
• Your child’s tolerance for specific medications, procedures or therapies
• Expectations for the course of the condition
• Your preference

Treatment may include:

• Limb manipulation and stretching
• Splinting of limbs
• Tendon transfers
• External appliances (to help realign misshapen fingers or hands)
• Physical therapy (to improve strength and function of the hand)
• Correction of contractures
• Skin grafts (these involve replacing or attaching skin to a part of the hand that is missing skin or that was removed during a procedure)
• Prosthetics (these may be used when surgery is not an option, or in addition to surgical correction)