Newsworthy Rare Conditions

Rebuilding the Mirror Hand

Mirror hand is an incredibly rare birth difference of the hand and upper extremity.  I have previously blogged about this diagnosis, specifically regarding how limbs form and how birth differences come to be- find the post HERE.  But I have not previously written about the reconstruction or rebuilding of the mirror hand.  And there is very little to be found on a Google search or in the medical literature.

The term mirror hand reflects the appearance of the hand and the duplication of the ulnar half (the non- thumb half) of the hand (such that it can look like a mirror image).  Typically there are 7 or 8 fingers without a thumb.  There can also be a duplication of the wrist bones and the forearm bones (in which case there are two ulna bones without a radius).  I will share more about the forearm and elbow in another post.

What follows is the case of Evan, a young boy with mirror hand.

Mirror hand with 7 fingers. 
Mirror hand with 7 fingers from the palm view.

Mirror hand with 7 fingers from the palm view.

When a child with mirror hand is examined, the use of the hand is important to understand.  The basic reconstruction/ rebuilding strategy is to pollicize (turn a finger into the thumb- see previous blogs on the pollicization HERE, recognizing that these are radial deficiency hands) one of the fingers- the question is- which finger is best to be the thumb?  Sometimes the strategy that makes the most sense is to use the fourth finger which means the hand will have, after reconstruction, 3 fingers and a thumb (which might seem crazy given the child started with 7 or 8 fingers).  In other cases, we can create a 4 finger and thumb hand in the mirror hand reconstruction.  The decision is based on quality of the fingers (size, mobility, and child’s use).  This video is instructive as Evan uses the space between the 4th and 5th fingers for function which makes the concept of a 4 finger and thumb hand appropriate.

Once we have decided how to proceed with reconstruction, two procedures are performed.  A pollicization is the most challenging but we also perform a procedure to help the wrist straighten or extend.  The wrist tends to flex because of a lack of the wrist extensor muscles (which is explained by the muscles)- surgery can strengthen the wrist extensors.  We also temporarily pin the wrist to allow healing.  Here are a series of images after the surgery while still in the operating room.

Mirror hand post pollicization.

Mirror hand post pollicization.

Mirror hand post pollicization.

We were very pleased with the pollicization and wrist reconstruction procedure for Evan. The later pictures are even more helpful in understanding Evan’s improving function.

Here is Evan shortly after surgery with his friend Owyn.  The kids share the diagnosis of mirror hand and the families have helped one another through the diagnosis and treatment at the St. Louis Shriners Hospital.

Evan and I shortly after surgery.  Note the tape on Evan’s new thumb which helps for positioning soon after surgery.

Evan showing off his new thumb after mirror hand reconstruction, approximately 7 weeks after surgery.  Note the pinch with the new thumb.

In this video taken approximately 3 months after surgery, Evan is using the new thumb for pinching the large metal balls.  
In this final video, also taken 3 months after surgery, Evan uses the new thumb for smaller object pinch.
Evan and his family traveled a long distance to come to St. Louis for the care of his mirror hand and he has, thankfully, done wonderfully.  The function (and appearance) of his hand are much improved.  We will follow his elbow (specifically the flexion of the elbow) for possible later reconstruction.  Evan’s mom agreed to allow me to post the images and videos in part to allow others with this rare condition to understand treatment options.
Charles A. Goldfarb, MD
My Bio at Washington University


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