Health Library

What Is Ulnar Dysplasia?

Babies with ulnar dysplasia (also called ulnar club hand) are born with a short or missing ulnar bone.

The ulnar bone is one of the two forearm bones. The short or missing ulnar bone causes the hand and wrist to turn outward toward the pinky side of the forearm. The hand, wrist, and elbow can have changes too.

What Are the Signs & Symptoms of Ulnar Dysplasia?

There are four types of ulnar

dysplasia
. Signs and symptoms depend on what type of ulnar club hand a child has.

Type I

This is the mildest form of ulnar dysplasia. The ulna is just a little shorter than normal and the wrist only turns out slightly.

Type II

The ulna is much smaller than normal. The other bone of the forearm (the radius) is bowed and the hand turns out more.

Type III

There is no ulna at all. The radius is bowed and the wrist is very turned out.

Type IV

There is no ulna at all. The wrist is very turned out, and the bones of the elbow are fused together so the elbow joint does not move well.

In all types, the fingers may be smaller than usual or completely missing. Ulnar club hand can happen on one or both sides.

What Causes Ulnar Dysplasia?

Ulnar dysplasia happens while a baby is developing in the womb. Ulnar dysplasia also can be associated with leg growth differences.

Sometimes it can happen as part of a genetic

syndrome
where there are other medical problems too.

Who Gets Ulnar Dysplasia?

Any baby can be born with ulnar dysplasia. It usually does not run in families.

How Is Ulnar Dysplasia Diagnosed?

A prenatal ultrasound might show ulnar dysplasia. Otherwise, doctors diagnose it when a baby is born.

X-rays of the bones in the hands and arms will help doctors decide on the best kind of treatment. Other tests might be done to see if the ulnar dysplasia is part of a genetic syndrome.

How Is Ulnar Dysplasia Treated?

Treatment for ulnar dysplasia depends on how severe the changes are. Treatment may include:

• exercises
• splinting and casting to help stretch the arm and wrist
• surgery

Looking Ahead

Even with challenges, children with ulnar dysplasia are very good about finding ways to use their hands well. Some tasks can be adapted, like having shoes with Velcro instead of laces. Work with the medical team to help your child learn what works best.