The classifications for hand deformities can vary. These classifications have been accepted by the American Society for Surgery of the Hand. There are currently seven groups of deformities 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 part of the body, such as the hand, or a missing structure, such as part of the arm bone. In the case of the complete missing part, surgery is not done. Instead, these children may get a prosthetic device early in their childhood. Types of this classification include:
Radial club hand. A radial club hand is a deformity that involves 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. Deformities of the wrist are usually operated on around 6 months of age.
Ulnar club hand. An ulnar club hand is less common than a radial club hand. This deformity may involve underdevelopment of the ulnar bone (the bone in the forearm on the side of the little finger), or complete absence of the bone.
Failure of parts of the hand to separate
With this type of deformity, the parts of the hand, either the bones or the tissues, fail to separate in the womb. The most common type of this classification is syndactyly. Syndactyly is when two or more fingers are fused together. There is a familial tendency to develop this deformity. If the fingers are completely fused together, it is considered complete. There are two types of syndactyly:
Another example of failure of the hand to separate is seen in contractures of the hand. Contractures of the hand may also develop as a result of a problem with the cells in the womb. A contracture is an abnormal pulling forward of the fingers of the hand. It is usually caused by problems with the muscles or skin. One of the common types of this classification includes congenital triggering. Congenital triggering occurs when one of the fingers is unable to extend. It is usually seen in the thumb. It may take some time in the child's development before it is noted that the child can't extend the thumb. Some of these cases improve on their own. Surgery is usually not done until the second year of life, but preferably before the age of 3.
Duplications of fingers
Duplication of fingers is also known as polydactyly. The little finger is the finger that is most often affected.
Undergrowth of fingers
Underdeveloped fingers or thumbs are associated with many congenital hand deformities. Surgical treatment is not always required to correct these deformities. Underdeveloped fingers may mean:
Overgrowth of fingers
Overgrowth of fingers is also known as macrodactyly, which causes an abnormally large finger. In this situation, 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 involved (usually the index finger). Surgical treatment of this condition is complex and the outcomes may be less than desirable. Sometimes, amputation of the enlarged finger is recommended.
Congenital constriction band syndrome
This occurs when a tissue band forms around a finger or arm, causing problems that can affect blood flow and normal growth. Ring constrictions are congenital (present at birth). This condition may be associated with other birth defects, such as clubfoot, cleft lip or cleft palate. The cause of the ring constrictions is unknown. Some theories suggest that amniotic banding may lead to ring constrictions around a finger or limb. In a few cases, the finger may need to be amputated.
Other generalized problems with the skeletal system
These are a rare and complex group of problems.