The space between the thumb and index (pointer) finger is crucial for function. We say that the thumb accounts for 40% of hand function – much of that function is related to grasping large objects in this ‘first webspace’. The thumb-index webspace, or as it is also called- the first webspace, can be tight or contracted for two basic reasons- a limitation present at birth or a limitation related to trauma.
Birth differences leading to first webspace contracture
I have previously shared thoughts on the first webspace in arthrogryposis a few times, here is one LINK. The first webspace can also be tight in other birth differences such as hypoplastic thumb, as seen HERE. I have also previously shared thoughts on different techniques to deepen various areas of tightness. This might be a little technical but here is that post as well, see link.
Trauma leading to first webspace contracture
When there is trauma to the hand, tightness or contracture can develop as well. This may be a deep abrasion or a burn. The abrasion type injury can happen on a treadmill when a child’s hand is injured by the spinning treadmill. Burn injuries are more obvious and can happen in various ways including grasping a coal or log in a cooking fire, falling into a campfire, or grasping something hot such as a curling iron. Ultimately, the skin will heal but will contract and lead to limitations in function and in motion. This type of injury is very common in underdeveloped countries that depend on cooking fires and are less common in more developed countries but certainly can still happen.
Thankfully, we have good treatment options. If there is a straight-line burn scar, the goal is to break up the scar band with a z-plasty. This can be highly successful. With a more complex contracture, a different type of procedure is required to break up the thicker, typically broader band. Often we use a flap of normal tissue to rotate into the area. The first webspace is a classic area to have a contracture and the dorsal rotation flap can be very helpful. In this procedure we take normal skin and advance it into the first webspace. We may have to release deeper tight tissues as well and sometimes even the deeper muscles. We divide or excise the poor skin and use the skin flap to cover the areas. Sometimes, advancing this normal skin is enough but sometimes skin grafts can be required also.
Here is one example. My ‘before’ pictures are limited but I believe you get a sense of the contracture. I have also already drawn my flap on the skin- this is normal tissue. Usually we can bring the thumb out about 90 degrees from the index finger. In this case, the patient is limited to about 45 degrees.
|Tight first webspace after trauma|
Then we have good after pictures, 4 weeks later. Notice how deep and wide the first webspace is. The thumb can be brought 90 degrees from the hand. The thumb moves normally again and there is healthy, soft skin in this critical area.
|First webspace after advancement flap. Notice the motion of the thumb.|
|Nice view of first webspace after deepening|
This patient has done well and I expect will continue to do well in the years to come.
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