Radioulnar synostosis is a condition in which the two bones of the forearm are abnormally connected, which limits the rotation of the arm. Radioulnar synostosis is usually congenital. However, it can also occur due to a forearm fracture or trauma.

The details on this page concentrate on congenital radioulnar synostosis.

What are the symptoms of congenital radioulnar synostosis?

The signifying symptom is a limitation in your child’s capability to rotate their forearm from a palms-down position to a palms-up position. A child with radioulnar synostosis may carry their elbow at an abnormal angle and have a short or bowed forearm.

What causes congenital radioulnar synostosis in babies?

A baby’s arms begin to form between the fifth and eighth week of pregnancy. The radius and ulna bones are connected in the initial stages. Later, these bones separate and develop into separate bones. If the radius and ulna do not fully separate, the baby will be born with radioulnar synostosis.

In most cases of congenital radioulnar synostosis occur for no known reason. 

Radioulnar synostosis |Diagnosis & Treatments

How is congenital radioulnar synostosis diagnosed in babies and children?

If your child was born with mild radioulnar synostosis, it might not be noticeable until they are of school age, and they may not even be aware they have the problem. Mild radioulnar synostosis in some kids is not discovered until adolescence.

If your child has a more severe form of congenital radioulnar synostosis, their forearm rotation will be significantly more constrained, and the condition will be more apparent. In these cases, the disease can be identified earlier — typically around age 6.

 To diagnose radioulnar synostosis, your child’s doctor will do a thorough medical history and physical exam. They can ask a CT scan or an x-ray. The images will assist them in making decisions on your child’s care, confirming the diagnosis, and evaluating the underlying structure of your child’s bones.

How is radioulnar synostosis treated in babies and children?

Treatment depends on whether your child is having problems using their arm. There are some kids with radioulnar synostosis who never require surgery. Instead, physical and occupational therapy can help your child meet normal developmental milestones and work around any activity limitations.

Your child may benefit from surgery if they have radioulnar synostosis in both arms or if their forearm is stuck in a posture that restricts the function of their arm. But surgery is typically done before kids start going to school.

Surgery involves repositioning the forearm so children can improve arm use. A surgeon will cut the forearm bones, turn them, then secure them in place with plates and pins, and a procedure called an osteotomy.

Following surgery, children generally stay in the hospital for one night and wear a cast on their arms for six weeks while their bones heal.