Sunday, March 15, 2015

The Big Thumb

The term ‘superdigit’ is utilized in congenital hand surgery to describe a digit that is larger than we expect. It is often related to the fusion of two digits into one and may be seen in cleft hand and central polysyndactyly among other conditions.  We also see large digits in other conditions such as Macrodactyly.  Occasionally, children may have a large thumb rather than large fingers.  Typically, these are very well tolerated and may not be obvious at a quick look at the thumb (whereas big fingers are almost always immediate noticeable as they are compared to the finger next door).  Additionally, the large thumb is unlikely to cause functional issues and will not block the motion of adjacent fingers.  Two children demonstrate some of the key issues.

The first example is that of a child with only two fingers- a thumb and a small finger.  This likely represents a cleft hand deformity with merging of two digits into the thumb.  This child has great function and motion of the thumb, but there is the concern of rotation- the thumb is more in the plane of the fingers compared to the location of the typical thumb (see previous Posts).  We plan to watch this child and only consider intervention if there is a functional problem.  The extra thumb is noticeable on clinical examination but the x-ray is especially helpful.  Also, compare the size of the thumb to the forearm bones and you can see how it is large.

Large thumb.  Note the size of the thumb compared to the only other digit and to the forearm.

Large thumb on x-ray.  Note the size of the thumb compared to the only other digit and to the forearm.

Another child has one thumb and 4 fingers which seem “normal.”  And the thumb at first glance is well developed also.  But it is a bit larger than expected and the nail is somewhat different.  In addition, the last joint of the thumb (the IP joint, near the nail) does not bend.  X- rays, shown below, tell the tale.  This is really an extra thumb.  However, the family is not interested in treatment as the child functions so well.

Large thumb with nail ridge suggesting the presence of two thumbs.  This child has radial polydactyly.

X- rays showing radial polydactyly as an explanation for the large thumb.

Charles A. Goldfarb, MD
My Bio at Washington University

Names Matter: Radial Polydactyly vs Duplicated thumb

There are a number of terms for describing the patient with two thumbs including, ‘duplicated thumb’, ‘extra thumb’, ‘radial polydactyly’, and ‘split thumb’.  While the particular term may not seem to matter, it does have important implications. ‘Radial polydactyly’ is a medical term describing the location and anomaly- it is not controversial.  ‘Split thumb’ may be the best lay term as it accurately describes that neither thumb is full sized.   The terms ‘duplicated thumb’ and ‘extra thumb’ imply that each thumb is normal but there are simply two thumbs.   These terms are, therefore, inaccurate.

In reality, the thumbs are almost small.  But, there is widespread belief, as stated by my previous partner, Paul Manske, that a small thumb after reconstruction is almost always satisfactory both in appearance and function.  Others, including TadaOgino, and Baek have agreed.

I believe the terminology matters for two reasons.  First, the family needs to understand that after surgery, the reconstructed thumb will not be the same size as the contralateral thumb.  When viewed in isolation (i.e., not comparison to the normal thumb), the smaller thumb size may not be apparent.  But when directly compared to the opposite thumb (obviously, not something most people typically do), the size difference may be noticed.
Radial polydactyly.  Notice the size difference between the normal thumb and each of the extra thumbs on the other side.

The second implication of thumb size is for the surgeon and his/ her choice of reconstruction technique.  Most of the time, the outer thumb is removed and the inner thumb is stabilized and reconstructed.  However, there are techniques to combine the two thumbs- the Bilhaut technique and Dr Baek’s modification of this Technique.

The bottom line is that there are several factors affecting the appearance of the thumb after treatment for ‘radial polydactyly’.  In our research that the most commonly cited reason for dissatisfaction after surgery was a crooked thumb, not a thumb that was too small.

Crooked thumb after radial polydactyly reconstruction.

This reinforces the importance of surgical strategy as it will affect thumb alignment after surgery.  Importantly, a second surgery may be required to address joint deviation in children with radial polydactyly but often not until the child is much older (7-8 years of age)- this was recently confirmed in another study.

Charles A. Goldfarb, MD
My Bio at Washington University

Saturday, March 7, 2015

Ulnar Deficiency- Thumb Rotation

I have posted a number of times about both ulnar longitudinal deficiency and thumb anomalies.     As previously noted, in ulnar longitudinal deficiency, we more commonly offer surgery for the hand compared to the forearm.  The forearm rotation abnormality is usually something that kids can adapt to as the shoulder offers so much compensatory motion.  The hand is, however, a bigger challenge.  I have previously posted about syndactyly and thumb rotation but I wanted to show a classic case of ulnar longitudinal deficiency in an older child.

This is a seven year old male who I have followed for years during which time he has not required any significant treatment.  He has ulnar deficiency affecting the hand.  His forearm is affected as well (absent ulna) but it does not functionally limit him.
Ulnar longitudinal deficiency with 3 fingered hand.

Ulnar longitudinal deficiency with 3 fingered hand.
This patient with ulnar longitudinal deficiency has excellent finger motion and a thumb which is somewhat under- rotated.  For that reason, we have watched him grow and develop for years and he has done well.  But over the last year he has noticed that he can't pinch well with that thumb- specifically he can't perform pulp-to-pulp pinch between the thumb and index finger.  The benefit of watching and waiting over the years (in this child with a moderate but not terrible deformity) is that he can better describe his frustration given his age and maturity.

Image from a non- affected patients.  Typical pulp to pulp pinch which maximizes fine motor skills such as stringing beads.

While he can pinch, as depicted below, he hopes to obtain more precise pinch.  At first glance, these pictures below show reasonable thumb function.  And, don't mistake this message, his thumb function is good.  But he can't quite rotate his thumb enough and he feels limited by this.  He has difficulties with certain fine motor tasks.  Many kids would not be bothered by this degree of under- rotation- but some, such as this child, are.  The general term for this issue is thumb in the plane of the fingers.  This child is somewhere between "normal" and the completely abnormal positioning.  This link shares our publication describing our experience with this issue.
Pinch with under rotated thumb in ulnar longitudinal deficiency.

Pinch with under rotated thumb in ulnar longitudinal deficiency.

And so, after many discussions with the patient, the family, and the hand therapists, we elected to proceed with a surgery to further rotate the thumb.  Sometimes we cut and rotate the metacarpal bone alone and sometimes we also add a tendon transfer.  In this case we only cut and rotated the bone.

Ulnar deficiency patient after thumb rotational osteotomy. 

Ulnar deficiency patient after thumb rotational osteotomy.

Our experience with rotational thumb osteotomy has been very good in children with ulnar longitudinal deficiency.  It improves precise function and kids and families have been pleased.

Charles A. Goldfarb, MD
My Bio at Washington University

Sunday, March 1, 2015

Syndactyly Outcomes and Challenges

Most children treated for syndactyly have an excellent outcome with normal finger motion and good maintenance of the reconstructed web space.  However, there are times with the ideal outcome does not happen.  A less than perfect outcome includes challenges like:
  •      prominent scarring,
  •      an inability to spread the fingers as widely as we would like,
  •      an inability to straighten the fingers fully,
  •      creeping of the web space (i.e., when the skin inches out towards the fingertips)
  •      rotation of the fingers
  •      deviation of the fingers
  •      nail irregularity
  •      discoloration of skin grafts (typically seen with groin skin grafts)

Here are some pictures of some of these challenges in syndactyly.

Syndactyly web creep between thumb and index finger.

Syndactyly web creep between index and long fingers.
Scarring after syndactyly reconstruction limiting finger extension.  Also not skin graft discoloration.

Rotation and deviation after complex syndactyly reconstruction.  Most notable in ring finger.

Here are some thoughts on risk factors and thoughts on these uncommon situations.

1.         The biggest risk factor is complex syndactyly- that is when the bones are joined together at the fingertip.  We know that these children often have rotation and deviation of the fingers as well as nail irregularity.  This was demonstrated in an article in the Journal of Hand Surgery in 2012. 
2.         Anytime there are more than two fingers involved, the risks increase.
3.         If the syndactyly is associated with a syndrome, the risks increase.
4.         There are technical risk factors for creeping of the skin or prominent scarring.  This means that the surgeon has some degree of control over these risks and an experienced surgeon can minimize these outcomes.  But, it is important to note that the surgeon can do everything “right” and sometimes a less than perfect outcome happens and additional surgery may be considered.
5.         We also believe that therapy after syndactyly reconstruction can be helpful to minimize problems with scarring.
6.         Finally, the nature of the syndactyly itself affects these outcomes.  Meaning some children and some types of syndactyly (they are not all the same, some are tighter, sometimes the skin is more pliable, etc.) increase risks.

The bottom line is that every child with syndactyly reconstruction will not have a perfect outcome and some will require a second operation.  We follow patients for at least several years after surgery and then intermittently until growth is done.  We know that scarred skin does not stretch as well as normal skin and the growing hand can experience problems with syndactyly scars.

Charles A. Goldfarb
My Bio at Washington University