Ulnar deficiency (or ulnar longitudinal deficiency) is much less common that radial deficiency, possibly only 1 case of ulnar deficiency per 10 of radial deficiency. And it is much different in the problems that it may cause. The forearm abnormality can include a deficient or absent ulna and flexor muscles BUT, it is much better tolerated than radial deficiency. There is less deformity and more wrist stability. And the shoulder can help compensate more easily for the deformity.
The hand abnormality in ulnar deficiency can include missing digits (so- called ectrodactyly) and syndactyly (abnormal joining of the fingers). I have previously blogged about ulnar deficiency– multiple examples are seen on this page. Also, I have written on multiple occasions about syndactyly here.
The following case demonstrates many important points in the understanding and treatment of ulnar deficiency and syndactyly.
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| Ulnar deficiency and syndactyly |
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| Palmar view of ulnar deficiency and syndactyly |
This child has a relatively normal forearm (slightly short ulna only) without deviation of the wrist. He has great wrist motion along with good elbow motion and forearm rotation. He has a great thumb, a full thumb web space, and two really good fingers. However, the fingers are joined together (syndactyly). To further promote hand function with independence of the fingers, the family and I elected to separate the fingers.
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| Syndactyly flaps from top of hand |
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| Syndactyly flaps from palm side. |
The flaps are elevated and sutured into place. We use absorbable sutures so nothing has to be removed and place a bulky dressing for 3 weeks.
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| Syndactyly reconstruction from top of hand. |
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| Syndactyly reconstruction from palm view. |
We performed this surgery as we believe it will take a really good hand in a child with ulnar deficiency and syndactyly and make it functionally better.