Ulnar Longitudinal Deficiency (Ulnar Club Hand) | Symptoms & Causes

What causes ulnar longitudinal deficiency?

Ulnar longitudinal deficiency is a birth defect. As with the majority of birth defects, researchers do not know why it occurs, but information that is known about ulnar longitudinal deficiency indicates that it doesn’t result from anything the mother did (or didn’t do) during her pregnancy.

Ulnar longitudinal deficiency develops early in pregnancy — sometime between the 28th and 56th day of gestation — when the bones of the hand and forearm are being formed.

It is sometimes, but not always, picked up on a prenatal ultrasound. Even if it is detected prenatally, the condition cannot be treated until after your baby is born.

The severity of ulnar longitudinal deficiency is also affected by the presence of an abnormal bar of fibrous tissue that may appear when the part of the ulna near the hand is absent. This fibrous tissue has a very limited ability to grow. It is attached to the ulnar side of the hand and wrist.

As the radius grows in the mothers' womb, the lack of growth in the ulnar side draws the hand into a deviated "club" position.

What are the symptoms of ulnar longitudinal deficiency?

The most severe cases of ulnar longitudinal deficiency lead to significant problems in the function of the hand, fingers and elbow. Your child’s entire arm will be shorter, with curving of her forearm and stiffness of her elbow and fingers.Your child’s thumb will either be very small or missing.

The arrangement of muscles and nerves may be unbalanced and some muscles and nerves may even be absent.