There is a group of patients with ulnar deficiency who have a radial head dislocation at the elbow. Here are the clinical pictures of one child
|Ulnar deficiency with radial head dislocation|
|Another view of ulnar deficiency with radial head dislocation|
The prominence at the elbow is the dislocation radial head. These radiographs demonstrate the dislocated radial head with a completely absent ulna bone.
|Ulnar deficiency with absent ulna and radial head dislocation.|
|Another view of ulnar deficiency with absent ulna and radial head dislocation at elbow.|
In this case, there is no pain and very good elbow and hand function. No intervention is planned. The next case of ulnar deficiency is similar and I include x-rays. Note the flexibility of the arm in almost all planes of motion. Especially notice the elbow motion which, while not perfect, is functional. There is no pain on examination. Thanks to mom for allowing us to post these pictures.
|Ulnar deficiency. The arm is somewhat short but extends almost fully.|
|Excellent elbow flexion in ulnar deficiency.|
|Again, good elbow flexion in ulnar deficiency. There are 2 fingers and a thumb but good overall hand function.|
|Ulnar deficiency motion of the elbow and shoulder are excellent.|
|Again, ulnar deficiency with great overall motion. Note the shortness of the extremity.|
These xrays will be very helpful in understanding this situation. In both of these radiographs, we can see the very short ulna. In reality, the distal 1/2 of the ulna is missing. Therefore, the radius is relatively long. Because of this length difference, the normal complex function of the two- bone forearm is affected. Rotation is limited but most importantly, the length of the radius causes a problem. The radius bends (should be almost straight) which we can see here. And, eventually, the radial head dislocates at the elbow- which we can see her also. If painful, there are several options to improve alignment, function, and pain. The most straightforward is to simply excise the prominent, painful part of the radial head. That may be enough to resolve the symptoms. Or, the radius and ulna can be fused together (one- bone forearm) which can be very helpful. At this point, the family and the child are very happy with his function and he has no pain. This issue is not unique to ulnar deficiency. We can see it in any process with alters the length of the radius or ulna. A common clinical situation is multiple hereditary exostosis with a short ulna.
|Ulnar deficiency with radial head dislocation.|
|Ulnar deficiency with dislocated radial head. Note how long the radius is compared to the short ulna.|