What causes club hands and feet?

Club hand, also called ulnar deviation, and clubfoot are congenital limb deformities present at birth. Both are thought to be caused by a similar mechanism resulting in a restriction of tissue growth of the affected bones. The club hand is the result of an unusual alignment of the bones of the forearm and wrist. These conditions range in severity from mild to extreme.

The exact cause of these conditions is unknown but are known to be caused by intrinsic (hereditary or genetic) factors and extrinsic (environmental) factors. There may also be an effect of the pressure within the womb.

A number of genetic syndromes cause these deformities and have been linked to ulnar deviation and clubfoot.

In about half of the cases, there is a family history.

A number of environmental factors have been identified that may cause these conditions including:

- oligohydramnios (low levels of amniotic fluid in the womb) that restricts movement and affects the development of the ligaments, muscles, and bones

- maternal diabetes and maternal smoking - the risk is higher if smoking also occurs in the first three months of pregnancy

- fetal exposure to certain drugs such as thalidomide which causes phocomelia (short limb deformities)

- some chemicals

- maternal alcoholism