Friday, June 22, 2012

Finger Lengthening




Lengthening a finger or thumb may be a good treatment option for a number of conditions including symbrachydactyly, constriction band syndrome, and ulnar deficiency.  Essentially any congenital or traumatic condition that leads to a shortened digit (or digits) may interfere with function.  If lengthening that digit will help pinch or large object grasp (i.e., soda can), then the procedure is considered.  Typically it is one metacarpal or one phalanx bone that is lengthened although it can be done for more than one digit.  Typically we lengthen the most distal bone (i.e., the farthest bone out) if it is long enough to allow the fixator to be safely placed (more later). 

I believe in lengthening for function.  It can really make a huge difference because it will simply increase the number of activities that the child can accomplish with the affected hand.  I do NOT believe in lengthening for appearance.  There is some information on the web and some things I have heard from patients about “growing” new fingers.  This does not make a lot of sense to me for a lot of reasons.  I use lengthening devices for 1 or 2 digits with a specific functional goal in mind.

The procedure has some risks, the most common being skin infection.  Most kids treated with a lengthener will have a skin infection but usually it can be treated with antibiotics by mouth.  Some have more serious infections.  The next most common issue is that the bone may not form as fast as we would like or as fully as we would like and additional surgeries may be required to help this process.

Fixators are not just used for fingers and we commonly use them in the forearm for radial deficiency http://congenitalhand.wustl.edu/2012/05/fixator-for-radial-longitudinal.html and sometimes for ulnar deficiency http://congenitalhand.wustl.edu/search/label/Fixators .  

The idea is that we can place a fixator on a short bone and then slowly grow that bone.  Typically less than 1mm a day.  A family member turns a dial 3-4x/ day to gradually make the bone longer.  We have to carefully watch the xrays to make sure the body is responding by growing bone.  This process is painless and if the child is having pain, something is usually wrong.  We grow the bone as long as possible to help function.  The fixator is on during the lengthening process (may be months but depends on how much bone we grow) and then stays on a bit longer while the bone truly heals (after we stop turning the dial).  More information is always available through our website at http://ortho.wustl.edu/content/Patient-Care/3220/SERVICES/Hand-Wrist/Congenital-Hand-Disorders.aspx

 
 Here is one example.
This is an unusual form of cleft hand (central deficiency).  There is no thumb except the floppy "nubbin."



Another picture of unusual cleft hand with absent thumb


This is the xray.  Notice the lack of the thumb.  The thumb metacarpal measures 22mm- good enough to support a fixator.


We have placed the fixator to allow a gradual lengthening of the bone.


Another view of fixator for cleft hand lengthening of a thumb.


Thursday, June 14, 2012

Arthrogryposis: General Thoughts


Arthrogryposis- What Works and What Is Still a Challenge

I want to restate how happy our arthrogryposis/ amyoplasia (AMC) (I use both of these terms together but these are very different diagnoses and may have different treatments) patients and families have been with three procedures. 

1)  External rotation osteotomy of the humerus.  If the arms are really rotated “in” (internal rotation position), function can be difficult as illustrated below.  When we cut and rotate the bones outward, function can be dramatically improved.  Blog: arthrogryposis-arm-rotation.html
2)  Posterior elbow release and triceps lengthening is perhaps my “favorite” operation in arthrogryposis.  It is done when the elbows will not bend (flex)- a straight position makes function like bringing the hands to the mouth impossible.  This release has been a dramatic functional improvement for patients.
3) Dorsal Carpal Wedge Osteotomy.  This operation brings the wrist out of the bent (flexed) position and allows the fingers to function better (if you are a parent, try to make a fist with your wrist maximally flexed- it is really hard).  Also, given that some kids have difficulty with one- handed activities, re- positioning the wrists will make the hands function together much easier (imagine clapping).

Now the difficult issues:

1)   Finger motion and function.  Many children have camptodactyly- a bent (flexed) position of one or more fingers.  Blog:camptodactyly.This can limit function to some degree but does not always terribly interfere with function- it depends on how severe the fingers are bent.  Additionally, kids may simply have poor finger motion- usually this is difficulty with making a fist.  This makes function difficult, specifically grasping objects.  Children are resourceful and can adjust to this limitation in a lot of different ways including by using both hands to lift and grab things.  Surgeries to improve motion of the fingers have not been typically successful.
2) Thumb position and thumb motion can be difficult in arthrogryposis as well but is usually less of a problem than the fingers.  First, the thumb does not need to move especially well to be helpful with activities.  As long as the thumb is in a good position and is stable, it can allow the child to grab large objects and pinch smaller ones.  Functionally, this is huge!  If the thumb is not in a good position (i.e., flexed into palm), function will be hurt both because the thumb is not in a good position and because it can interfere with the fingers.  Medicine can help with thumb positioning.  Sometimes splinting can help, and sometimes a surgery can be helpful to re- arrange the skin, release tight muscles, and tighten tendons to improve the thumb position.  A partial fusion can also be helpful for some children.  So while the thumb can be a challenge, we can usually help kids get the most out of their thumbs/ hands.  Blog: Arthrogrypotic Thumb
3)  The lack of muscle strength will limit active motion (i.e., moving the arm using muscle power only).  This is ultimately the greatest challenge for the patient with arthrogryposis.  Sometimes, we can move other muscles to make up for the ones that are weak or not working well.  These surgeries, called muscles transfers, are helpful but often not ideal for a number of reasons (including the issue that finding good muscles can be difficult in arthrogryposis).  For example, to provide active elbow flexion, at least 5 muscle transfers have been recommended.  All would agree that none is perfect and all have limitations.

As always, learn more about congenital disorders at: Washington University Hand-Wrist/Congenital-Hand-Disorders

Friday, June 1, 2012

Radioulnar Synostosis

Radioulnar synostosis literally means a bony union between the two forearm bones.  Normally, the ulna bone acts as a straight "post" to anchor the wrist to the elbow.  The radius bone rotates around the ulna to allow the forearm to turn palm up and palm down.  This rotation is helpful for daily activities and allows many actitivies such as typing on the keyboard (palm down or "pronation") or hold change (palm up or "supination").  Almost all rotation comes through the forearm (ie the relationship between radius and ulna) but some can come through the wrist bones also.

Some kids are born with a bony connection between the radius and ulna.  This bony "bridge" can also develop after a trauma in an adult.  When that happens, the bones are no longer separate and the ability to rotate the forearm is not present.  Because the shoulder is so mobile, we can make up for some loss of forearm rotation with shoulder movement.  It is pretty easy to pull arm away from body- abduct- and the hand assumes a palm down position.  It is less easy to move the shoulder in such a way to allow the palm up position.

The bottom line is that kids adapt amazingly well to radioulnar synostosis.  Often, families do not even realize this condition is present until after kids start school.  There is no pain and, as noted above, some rotation can be achieved through the wrist.  When both sides are affected, it may be a little more challenging to adapt.  Additionally, it matters in which position the forearm is fused.  The forearm can be "stuck" in full palm up (supination), full palm down (pronation), or anywhere in between.  The best position is half- way between (the clapping position) which allows the patient to use the shoulder to help accommodate in both directions.  Palm down is better than palm up as so many of life's activities are palm down (keyboarding, etc).

In a small number of kids, the forearm position causes trouble with activities.  In those, a small surgery can be done to reposition the forearm in a better position for function.  The pictures below show a patient positioned with both forearm in mid rotation.  He has no issues with function despite his limited rotation.

Synostosis with full elbow extension
Synostosis with full elbow flexion


Synostosis with attempted supination- palm up

Synostosis with attempted pronation- palm down

Xray showing synostosis near elbow.  The two bones are joined together.