Ulnar Longitudinal Deficiency (Ulnar Club Hand)

What is ulnar longitudinal deficiency?

A diagnosis of ulnar longitudinal deficiency, previously known as ulnar club hand, means that your child’s wrist is in a fixed and bent position toward the side of the hand with the little finger. It’s caused by an ulna (the bone that connects the elbow to the forearm) that wasn t formed correctly in the womb. Your child’s thumb may also be deformed or absent.

When describing a particular side of the arm, you may hear your child s doctor refer to the “radial side,” which indicates the side of the arm on which the thumb lies, or the “ulnar side,” which describes the side on which the little finger lies.

These terms are used rather than “inner” or “outer” arm because the palm of the hand can face either forward or backward.

Ulnar longitudinal deficiency is less common than radial longitudinal deficiency. It’s present in about 1 in 100,000 babies.

There are the four different types of ulnar longitudinal deficiency:

  • Type I: In the mildest cases, the ulna is merely slightly smaller than normal and there is minimal deviation at the wrist. This won’t cause many problems in your child’s development.
  • Type II: This is the most common form of ulnar longitudinal deficiency. It involves a partial absence of the ulna and the hand appears deviated toward the ulnar side. Bowing of the radius may also occur.
  • Type III: Your child’s ulna is completely absent, leading to limited range of motion at the wrist. The elbow joint may also be disturbed or even fused with no motion. There may also be underdevelopment or absence of the thumb, which interferes with hand function.
  • Type IV: Here, there’s an abnormal connection between your child’s radius and humerus, resulting in bowing of the radius and hand deformations.

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.

How we care for ulnar longitudinal deficiency

The Orthopedic Center’s Hand and Orthopedic Upper Extremity Program and our Department of Plastic and Oral Surgery s Hand and Reconstructive Microsurgery Program have treated thousands of babies and children with ulnar longitudinal deficiency and other hand problems. We are experienced treating conditions that range from routine to highly complex, and can provide your child with expert diagnosis, treatment, and care. We also offer the benefits of some of the most advanced clinical and scientific research in the world.

Our Orthopedic Center is nationally known as the preeminent center for the care of children and young adults with a wide range of developmental, congenital, neuromuscular, sports related, traumatic, and post-traumatic problems of the musculoskeletal system.

Our Department of Plastic and Oral Surgery is one of the largest and most experienced pediatric plastic and oral surgery centers anywhere in the world. We provide comprehensive care and treatment for a wide variety of congenital and acquired conditions, including hand deformities.