Forearm deformity Synostosis

Radioulnar Synostosis, revisited

Radioulnar synostosis has been previously discussed in this blog

In that post, I discussed that in most cases, surgery was not necessary because kids typically function very well. However, sometimes that is not the case.  Most kids with radioulnar synostosis are diagnosed around age 7.  Sometimes it is picked up earlier but around age 7, activities increase and kids with synostosis may realize limitations.  A recent patient is a good example of problems that can exist with radioulnar synostosis.  This patient presented to us at age 12.  She had absolutely no pain but both forearms were palm down (fully pronated to use the therapy language).  She was in great position to type but not to play sports, not to hold a tray, and not to get change or hold M&Ms.

             Resting position of radioulnar synostosis for this patient.  She is fully pronation or palm down.

In this picture of radioulnar synostosis, the patient is trying to turn her palms up.   If you look carefully, her forearms are still palm down.
These pictures are great examples of the difficulties that can exist.  The bottom picture shows that patients can use the wrist to change the forearm/ hand position (kids are really limber and this proves it).  However, despite this increased wrist motion, the forearm still doesn’t move and function is still limited.
The x-rays are educational as well.
Radioulnar synostosis x-ray.  A single x-ray can be confusing as this one is.  The diagnosis is not clear.

The diagnosis of radioulnar synostosis is now clear.  The radius and ulna are one bone near the elbow.  Additionally, the radial head is dislocated.  In some children the dislocated radial head can cause problems, but not in this child.

The treatment options are simple.  Obvservation versus surgery to reposition the forearm in a better position to allow function.  An osteotomy, or cutting of the bone, is the way to take the forearm from a palm down position and place it in a position between palm up and palm down- neutral rotation (clapping hands position).  Once repositioned, shoulder movement can help compensate and allow the patient to function in all positions.  In 2013, despite many advances in medicine, we do not have a way to restore motion.

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