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Radial ray anomaly

What is a Radial Ray Anomaly?

A Radial Ray Anomaly (Radial dysplasia, Radial Longitudinal Deficiency) is the underdevelopment or total loss of the radius bone in the forearm.

This condition often affects the development of the thumb (see hypoplastic thumb). Many children with radial ray anomalies will have some thumb hypoplasia. Some children are born with no thumbs, others have stiff and small thumbs. Camptodactyly (stiff fingers) is commonly found with this condition. In some cases, there may also be problems with bending the elbow.

What are the Different Types of Radial Ray Anomalies?

There are four basic types of radial ray anomalies:

Type 1. The radius bone is slightly short, causing the hand to bend sideways at the wrist (often associated with a hypoplastic thumb)

Type 2. The radius bone is very short, causing the ulna bone to curve sideways and support the wrist poorly.

Type 3. Only part of the radius bone is present, causing the ulna bone to curve sideways providing no support for the wrist

Type 4. No radius bone is present, causing the ulna bone to be short and curve sideways. The hand has no support and is not positioned properly.

How Common is This?

One in 100,000 children are born with radial ray anomalies. They are slightly more common in males and in Caucasians. This condition affects both arms in 38-50% of children.

Associated Syndromes

Radial ray anomalies are seen with thrombocytopenia absent radius syndrome (TAR), Holt Oram Syndrome, VACTERL, and Fanconi's Anemia.

Why Does This Occur?

Radial ray anomalies result from injury to the developing arm during the fourth to seventh week of pregnancy. In some cases, this can be caused by exposure to factors in the environment including compression, inflammation, nutritional deficiency, infection, and chemical and drug exposure. Usually no specific cause is found. It is thought that this condition is not genetically inherited, except when associated with other syndromes.

What are the Treatment Options?

The Occupational Therapist and Plastic Surgeon will discuss with you the appropriate options for your child. The most important goal for surgery in children with radial ray anomalies is achieving the best possible functional use of the hand. Surgery to improve the look of the hand may not improve the use of the hand in daily activities. An evaluation of the children’s upper limb and fine motor function is a priority to determine the surgical options available. For children who can bend their elbow, centralization surgery, a procedure that stabilizes the wrist on the ulna bone, may be an option. Preparation for this surgery involves stretching and splinting of the wrist joint to straighten the hand. Surgery may also be recommended for hypoplastic thumbs.