Disease at a Glance

Congenital radioulnar synostosis is a rare condition in which there is an abnormal connection (synostosis) of the radius and ulna (bones in the forearm) at birth. The condition is present in both arms (bilateral) in approximately 60% of cases. Signs and symptoms depend on the severity of the abnormality and whether it is bilateral; people with the condition often have limited rotational movement of the forearm. Pain is usually not present until the teenage years. There are 2 types of radioulnar synostosis: type 1 and type 2. In type 1, the fusion involves 2-6 cm of the area between the radius and ulna bones which is closer to the elbow and the knobby end of the radius that meets the elbow is absent (radial head). In type 2, the fusion is farther from the elbow and there is dislocation of the radial head. Both types result in a limitation of inward roll (pronation) and outward roll (supination) of the forearm, and in type 2 there is also a restriction of extension at the elbow. Congenital radioulnar synostosis is due to abnormal fetal development of the forearm bones, but the underlying cause is not always known. It is sometimes a feature of certain chromosome abnormalities or genetic syndromes. Some cases appear to be inherited in an autosomal dominant manner.
Estimated Number of People with this Disease

This section is currently in development.

What Information Does GARD Have For This Disease?

Many rare diseases have limited information. Currently GARD is able to provide the following information for this disease:

*Data may be currently unavailable to GARD at this time.
When do symptoms of this disease begin?
The most common ages for symptoms of a disease to begin is called age of onset. Age of onset can vary for different diseases and may be used by a doctor to determine the diagnosis. For some diseases, symptoms may begin in a single age range or several age ranges. For other diseases, symptoms may begin any time during a person's life.
Before Birth
Birth-4 weeks
Infant Selected
1-23 months
Child Selected
2-11 years
12-18 years
19-65 years
Older Adult
65+ years
The common ages for symptoms to begin in this disease are shown above by the colored icon(s).


These symptoms may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list does not include every symptom.
This disease might cause these symptoms:

12 Symptoms

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This section is currently in development. 

Last Updated: Nov. 8, 2021