Bilateral congenital radioulnar synostosis

Case contributed by Matt Skalski


Limited forearm range of motion in supination/pronation.

Patient Data

Age: Child

There is moderate anterior bowing of the radius bilaterally, with osseous continuity between the proximal radii and ulnae. This fusion involves the entirety of both radial heads, and fixes the forearms in a pronated position. 

This illustration demonstrates the functional difficulties that occur when the forearm is fixed in a pronated position as a result of radioulnar synostosis. 

Case Discussion

Congenital radioulnar synostosis is the most common congenital functional disorder of the elbow. It demonstrates an autosomal dominant pattern of inheritance with no sex predilection and is bilateral in 60-80% of cases. Approximately 400 cases of congenital radioulnar synostosis have been documented in the worldwide literature, and the average age at diagnosis is 6 years.

Four types of congenital synostosis are described, as follows: 

  • type I: fibrous synostosis, does not involve bone and is associated with a normal, articulating radial head
  • type II: osseous synostosis, associated with a normal, articulating radial head
  • type III: osseous synostosis, with a hypoplastic and posteriorly dislocated radial head
  • type IV: short osseous synostosis with an anteriorly dislocated, mushroom-shaped radial head

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.