Radial Aplasia: Symptoms, Causes, Treatment, and More

Radial aplasia is a condition that occurs when the radius bone in the forearm does not fully develop.

This condition is also called radial club hand or congenital longitudinal deficiency. Radial aplasia is a birth defect that ranges from a mild shortening of the bone to a complete absence of the bone. In some cases, the thumb is also missing.

This article discusses radial aplasia—its symptoms, causes, diagnosis, and treatment.

Types of Radial Aplasia

The forearm has two parallel bones: the radius (in line with the thumb side of the hand) and the ulna (in line with the pinky side of the hand).

Radial aplasia exhibits as four types, which range in severity. Type 1 is the mildest, while type 4 is the most severe.

• Type 1: The end of the radius (where the bone meets the hand) is mildly shortened.
• Type 2: More significant shortening of the radius. The ulna might also be shortened and bowed out. In some cases, the thumb might also be missing.
• Type 3: Severe shortening of the radius, with more significant shortening and/or bowing of the ulna. The hand and wrist are severely tilted toward the radius.
• Type 4: The radius is missing entirely. The ulna is bowed and the wrist and hand are severely tilted toward the side of the forearm where the radius should be.
  

Symptoms of Radial Aplasia

The main symptom of radial aplasia is deformity of the forearm, wrist, and hand. This condition is not typically painful. However, it can lead to developmental delays in fine-motor skills and activities of daily living (ADLs).

What Causes Radial Aplasia?

The exact cause of radial aplasia is not always known. In some cases, it is part of an underlying genetic condition, such as:

• Fanconi anemia: This condition is characterized by the decreased production of blood cells. More than 50 percent of people with this condition also have physical deformities.
• Holt-Oram syndrome: In addition to limb deformities, 75 percent of people with this condition also have heart malformations.
  
• Duane-Radial ray syndrome: This condition, also known as Okihiro syndrome, causes upper limb defects and issues with eye movement.
• Thrombocytopenia-absent radius syndrome: Individuals with this condition are missing a radius bone in each arm and have decreased bone marrow production.
• Acrofacial dysostosis 1, Nager type: Upper-extremity deformities are more common than leg deformities with this condition. It also causes deformities in the skull and facial bones.
• Baller-Gerold syndrome: This condition causes deformities in facial bones as well as the radius and fingers. It can also affect bones in the legs.
• VACTERL association: This disorder causes defects in multiple areas of the body. The acronym in its name stands for: vertebral defects, anal atresia (abnormalities), cardiac defects, tracheo-esophageal fistula (a connection between the trachea and esophagus that should not be there), renal (kidney) abnormalities, and limb deformities.

Birth defects such as radial aplasia might also be caused by medications taken during pregnancy or poorly controlled diabetes in the mother.

Treatment for Radial Aplasia

Treatment for radial aplasia depends on the severity of the condition.

Type 1 Treatment

Mild cases of type 1 radial aplasia are often treated conservatively, with stretching and splinting. The goal with this treatment is to improve range of motion and help prevent the hand from getting "stuck" in a tilted position. Stretches are performed frequently throughout the day, and the person wears a splint between stretching sessions.

Over time, as range of motion improves, the splint is weaned during the day and worn only at night.

Type 1 radial aplasia can also be treated with surgery. Cuts are made in the bone—a procedure called osteotomy—to help lengthen the shortened radius during the growing years of childhood. This often requires use of an external fixation device for a period of time to help stabilize the bone.

Radial aplasia impacts development of fine- and gross-motor skills. Infants with this condition often require physical therapy and occupational therapy to improve their ability to grasp items, play with toys, and use their hands during gross-motor activities, such as crawling.

Adaptive equipment might also be needed to improve independence with activities of daily living.

Treatment for Types 2, 3, and 4

Types 2, 3, and 4 radial aplasia require surgery.

There are eight carpal bones in the wrist, positioned in two rows of four. The proximal carpal row—bones closest to the forearm—form a joint with the end of the radius. This joint is where wrist movement occurs. In normal anatomy, the ulna is a little shorter than the radius at the wrist.

Surgery for radial aplasia aims to reposition the hand and wrist to improve function.

Surgery options include:

• Centralization: This procedure positions the wrist over the center of the end of the ulna bone.
• Radialization: During this procedure, the wrist is repositioned over the radial aspect of the ulna, which essentially converts the ulna into a functioning "radius."
• Ulnarization: This procedure positions the wrist on the ulnar side of the end of the ulna.

After surgery, an external fixator is used for about three months while the bones heal in their new position. When the device is removed, the arm is typically in a cast for another month. After casting, a removal splint is often worn at night to help maintain the wrist position.

Occupational therapy is an important part of the recovery process to help the child learn how to function after radial aplasia correction surgery.

Summary

Radial aplasia is a deformity characterized by a shortened or absent radius bone in one or both forearms. This condition develops before birth. The exact cause is not known, but the deformity often occurs with specific genetic medical conditions. Radial aplasia is diagnosed with fetal ultrasound and then a physical exam and X-rays after birth.

Treatment for radial aplasia depends on the severity of the deformity. Splinting and stretching can improve range of motion in mild cases, but surgery is often required to fix more significant deformities.

A Word From Verywell

Finding out that your child has a radial aplasia deformity can be overwhelming. However, treatment for this condition begins soon after birth. When surgery is required, it is often performed between 12 and 18 months of age, to allow the child to have use of their hands while they develop important fine-motor and gross-motor skills during the early years of childhood.