Thumb Deformity

The thumb is vital for high level hand function.  The concept of the opposable thumb- the thumb that can meet the fingers for pinch and other high level function- has been said to separate man from at least some of our primate 'relatives'.  In the growing child, the thumb is key for exploring the world and, most notably at school age, for fine motor manipulation with pens, pencils, scissors, and other tools.

As a surgeon, our job is to assess thumb function and thumb alignment and, when necessary, offer intervention to assure each child can obtain maximal function.  For some children, therapy can help with strength and help the child and family understand how to best function.  For others, surgery can provide better alignment, rotation, or stability in an effort to allow the thumb ideal interaction with the fingers and with the world.  Thumb stability is key to function but a lack of stability is not something that kids complain about (or know how to complain about).  But pinch is affected and the surgeon should look for this issue as it is correctable with good results.

Thumb stability is most commonly compromised in two situations.  First, the underdeveloped or hypoplastic thumb.  I have previously blogged about the hypoplastic thumb HERE, among other blog posts.  A typical hypoplastic thumb is small, has poor muscle and has an unstable joint.  Surgery can address the instability and the lack of muscle support.

Hypoplastic thumb.  Not the rotated position of the smaller thumb.

And second, thumb polydactyly, or extra thumb, can be associated with instability.  The most common scenario of instability in thumb polydactyly is after removal of the extra thumb.  That is, the patient has surgery to remove the extra thumb and a lack of stability or a zig-zag deformity becomes a problem several years later.

Triphalangeal thumb, or a thumb with three bones rather than two, is often associated with polydactyly (extra thumb).  Early surgery may be offered to remove the extra thumb and often the third bone in the primary thumb is initially watched to confirm whether or not that bone will cause problems.  I have previously blogged about the problematic triphalangeal thumb HERE.

This is another example.  This child had an extra thumb removed and there is deformity of the remaining thumb which is affecting function including pinch.  There is a lack of pinch strength related to both a lack of stability and the deformity.  In addition, the fact that the thumb has an extra joint (an extra area to bend) can change the way the thumb works.  Adults have shared that this extra joint is not a good thing for function.

Triphalangeal thumb.  The thumb is small and crooked compared to the normal thumb.

Another view of the deformity of the triphalangeal thumb.

Palm view of the triphalangeal thumb with visible scar from previous extra thumb excision.

Triphalangeal thumb with small middle bone (middle phalanx)

Triphalangeal thumb with small middle bone (middle phalanx).  The angulation of the thumb is clear.

Thumb stability is key to function.  This child will benefit from stability and correction of deformity.

Charles A. Goldfarb, MD
My Bio at Washington University
congenitalhand@wudosis.wustl.edu

Bent Finger: Surgery for Camptodactyly

I have blogged several times on camptodactyly as it is a common finger anomaly and I have received regular requests for information on the topic.  Those posts can be found HERE and HERE and HERE and HERE.    The popularity of the topic camptodactyly can be seen with the large number of comments and questions on the last link.

The medical literature tends to assess outcomes and causes of camptodactyly- neither of which is easy to do.  There are many reported causes including unusual tendons, tight tendons and an imbalance between tendons that bend (too strong) and straighten the finger.  There is also much information about associated conditions and syndromes (arthrogryposis, for example).  A Google search on camptodactyly returns 86, 500 results with many of the first page results from hospitals, Wikipedia, and other information sites.

My general philosophy in treating camptodactyly is therapy first which includes splinting and stretching.  Most kids will respond to therapy and, even if not perfect, the finger becomes fully functional and surgery is avoided.  Some kids, unfortunately either fail therapy (therapy is attempted but not successful) or can never really try it because the deformity is too severe to allow effective splinting.  Those kids may benefit from surgery although families should know that surgery is unlikely to provide a fully mobile finger.

I wanted to share early outcomes of one child with camptodactyly.  He had an isolated ring finger flexion deformity without associated syndrome or other anomalies.

Camptodactyly, bent finger deformity, resting posture.

Camptodactyly, bent finger deformity, resting posture.

Camptodactyly, bent finger deformity, resting posture.  Attempted extension demonstrates a nearly 90 degree contracture.

This child was sent to therapy but ultimately, the degree of deformity contributed to a failure of splinting and stretching.  Surgical release of the tight structures in this camptodactyly was performed with straightening of the finger.  In addition, once such fingers are released, there is often a skin deficit.  We have been using a rotation flap to cover this deficit and avoid bigger flaps or skin grafts.

Camptodactyly 1 week after surgery.  The pin is still in place (removed that day).  Note the triangular flap which was rotated to cover the deficit.

Camptodactyly 5 weeks after surgery.  Note how the patient can straighten the finger and the flap is healed nicely.

Camptodactyly 5 weeks after surgery.  Flexion of the finger continues to improve.

This patient is doing well and both bending and straightening the finger should improve with time and therapy.  The lack of full flexion (bending) as demonstrated above does demonstrate a key point in the treatment of kids with camptodactyly- we need to be careful to avoid loosing finger flexion and work on flexion and extension (straightening) after surgery.

Camptodactyly is a common birth difference of the upper extremity which thankfully often responds to splinting and surgery can be avoided.  While surgery is never a perfect solution, it can be very helpful in the right children.

Charles A. Goldfarb, MD

My Bio at Washington University
congenitalhand@wudosis.wustl.edu

Clasped Thumb.

Clasped thumb is an uncommon diagnosis in which the thumb is held in the palm.  While there are several potential reasons for this positioning, in many cases it is simply due to a delay in muscle development of the thumb extensors.  Over time, those muscles (EPB and EPL) can (but may not) strengthen sufficiently to allow normal function.  Our job during the interval between diagnosis and recovery is to keep the thumb flexible so that if the muscles do develop, the thumb can straighten.  This mainly entails therapy to straighten the thumb to stretch it and sometimes we use splints to do the same.  Occasionally, a soft Benik Splint can help place the thumb in a better position to allow function.

Often clasped thumb affects both sides but the recovery may not be equal.  In the patient below, the right side was worse from early childhood.

Clasped thumb with the fingers straightened.

Over time, in this patient, the left side recovery but the right side did not.

Continued clasped thumb in a 2 year old.

This video demonstrates that the left thumb has recovered nicely but the right still has notable limitations.  We will continue to discuss surgery while giving this clasped thumb a bit longer to recover on its own.

I have previously blogged about congenital clasped thumb- see HERE.  I hope this video sheds light on the diagnosis.  

A couple of further thoughts on congenital clasped thumb.

1)  Surgery can be helpful.  If the patient fails to gain the strength to straighten the thumb, surgery can improve function.  Typically we rearrange tendons to add another muscle unit to help the straightening process.  We do want to allow sufficient time for the thumb to gain strength and recover on its own, but this does not always occur.

2) Generally the diagnosis of clasped thumb is clear but not always.  Other diagnoses must be considered including an association with syndromes or even things like cerebral palsy (CP).  CP can have a thumb in palm deformity but it is related to tight muscles (spastic muscles) rather than weak extensor muscles.

Clasped thumb is a diagnosis that can have a very favorable outcome with or without surgery.  

Charles A. Goldfarb, MD

My Bio at Washington University
congenitalhand@wudosis.wustl.edu