I have previously written many times about arthrogryposis and several years ago focused on the thumb– see Link. As with every part of arthrogryposis, each child is affected differently. But the thumb is affected, the position of the thumb can really make a big difference. Consider these points:
1) The thumb normally provides about 40% of hand function. So, in a child with arthrogryposis and a thumb which is not functioning well- overall hand function will be affected. The thumb web space is key for holding big objects such as a soda can and, if the thumb is tight, that action may not be possible or may require using both hands together.
2) Not only will a poor thumb limit hand function, it can be doubly bad by also interfering with function by getting in the way. Kids with more notable arthrogryposis often use both hands together (bimanual activities). If the thumb is in the palm and can’t be moved, using the two hands together may be challenging.
As I have previously written: Link to arthrogryposis posts, there are several surgeries which we in St. Louis like to use to help function including, elbow release, humerus rotational osteotomy, wrist closing wedge osteotomy, and thumb first web space release.
The tight thumb in arthrogryposis is likely due to several factors including limited muscle development and tight skin. The thumb rests across the palm and straightening it can be tough. To treat kids so affected, we can rotate skin from the index finger across the thumb web space while releasing tight muscle in the palm. Sometimes we add a tendon transfer for thumb positioning. We often hold the thumb in a better position with a metal pin for a few weeks while the soft tissues heal. Here are a few pictures showing a range of presentations for kids with arthrogryposis and a tight thumb.
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| Somewhat less severe but still notable tight thumb in arthrogryposis. Passive motion, demonstrated, was much better than active motion or the patient’s ability to pull the thumb out of the hand. |
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| Severe hand involvement in arthrogrypsosis |
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| Severe hand involvement in arthrogrypsosis |
If therapy fails to improve thumb position and thumb mobility, surgery can be considered. Surgery improves thumb passive motion and hopefully also allows the child the ability to actively move the thumb to a better position for function. Consider these pictures after surgery:
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| The thumb in arthrogryposis several weeks after surgery with healing of the flap and a markedly improved thumb position. |
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| The thumb in arthrogryposis several weeks after surgery with healing of the flap and a markedly improved thumb position. |