Sunday, April 21, 2013

Pseudarthrosis of the Forearm

Pseudoarthrosis or, more commonly, pseudarthrosis literally translates to “false joint.”  The term Pseudarthrosis is used commonly in the situation of a fracture nonunion.  For example, if the shinbone, the tibia, does not heal after a fracture, a nonunion develops.  Eventually the nonunion will develop into a pseudarthrosis- related to motion between the bone ends.  There is fluid and a joint like appearance to this space.

While this can happen in children, more often (but still really rare) some children are born with a pseudarthrosis, a congenital anomaly.  We don’t know the reasons for these situations but these pseudoarthroses can occur in in specific locations such as the tibia.  The tibia is indeed the most common location for pseudarthrosis and about 50% of the time these patients have neurofibromatosis (NF)type I.  It can also occur in the clavicle although these cases are not usually related to NF- see my previous blog on this topic:

The forearm is a common site of Pseudarthrosis in NF.  This can involve the radius or, more commonly, the ulna bone.  Anatomically, the forearm and the lower leg both have two bones (radius and ulna in the forearm and tibia and fibula in leg).  The difficulty with a pseudoarthrosis in either location is the differential growth of the 2 bones.  When one bone doesn’t grow as the other grows, deformity develops and may be accompanied by dislocation (typically of the radial head).  We see similar issues in the condition of osteochondromatosis- also directly related to the differential growth.  Pain can be an issue but typically is not. 
Ulna pseudarthrosis.  A good portion of the ulna is missing.  See the forearm curve.
Ulna pseudarthrosis from side view.

Above is the ulna pseudoarthrosis and below is the radius pseudarthrosis.

Radius pseudarthrosis.  Not the curvature of the forearm.  The radius is very short compared to the ulna.
Another view of radius pseudarthrosis.

Treatment is appropriate to create a unified bone that will balance the forearm and prevent progressive deformity and angulation.  There are a variety of different approaches to achieve healing and improved alignment:
      1)  Cleaning out the nonunion site, filling the site with bone graft (typically from hip) and often bone morphogenic protein (BMP- an off the shelf bone stimulant).
2    2)  Free fibula vascularized bone transfer.  In this procedure, a wider area of the Pseudarthrosis site is removed and normal bone from the fibula is substituted into the void.  The beauty of this procedure is that the fibula bone is unaffected and can be brought to the forearm with a blood vessel to maximize healing.  The negative of this approach is related to problem of taking this bone from the leg.  While fortunately these complications are rare, they do include issues with muscle (FHL) function (affects toes), temporary sensory issues, pain, and ankle deformity.
·         3) External fixator deformity correction and bone grafting (often with BMP).  

Thursday, April 18, 2013

Family Challenges

I just read a very interesting article in Money Magazine, May 2013 issue.   It is called "Paying for Finn" and is written by Jeff Howe.  The article details the challenges in caring for a special needs child.  A child such as Finn on the autism spectrum brings different challenges than most children with birth anomalies of the upper extremity but the article is interesting nonetheless. It got me thinking...

Some of the children I see- often those children with a syndrome or chromosomal difference- do have larger cognitive issues which affect their interaction with the world.  These problems are different than a child with autism but still can be a challenge.  The majority of the children do not have such issues.

Most of the children that I see and treat with upper extremity birth anomalies are behaviorally just like every other kid their age.  A 2- year old tantrum is the same in a child with radial deficiency as it is in a child without it.  At certain ages, however, upper extremity differences will be a challenge.  I am no psychologist (and am lucky to work with some very good ones) but I have learned of two periods of challenge for the child and family- kindergarden and 7th grade (I learned some of this at Texas Scottish Rite Hospital also). These are times of a growing self- awareness and a time when children are working to  understand who they are and where they fit in their social world.  In kindergarden, kids ask a lot of questions.  As long as the child with the difference (whatever that might be) has a response to questions from other kids, all will usually be well. Some kids say something like "God made me different" and some say "an alligator bit my hand off."  It really doesn't seem to matter what one says, just that the child has a response to the questions.

As a parent and a caregiver, I have learned that every child brings unique challenges and every person has "something".  The Something is some challenge, some difficulty which may or may not be apparent.  In kids with upper extremity birth differences, the difference is physical and is visible.  It may or may not slow the child down, it may or may not allow him to play basketball or play the piano or whatever.  This difference will affect the way the child interacts with the world mainly because it affects the way the world interacts with him or her.

The other time frame which is a challenge is the 7th grade.  Again, kids are figuring out their place in the world and comparing themselves with others.  There are no easy answers to questions from others at this point and the more comfortable and confident the child with the difference is, the more successful they will be in navigating this difficult time.  Support at home is clearly important in gaining the skills to get through the questions at this age.

I hope that this post generates some thoughts from others who may well have different opinions and different feelings.  I am sure I will learn from those thoughts...

Wednesday, April 10, 2013

Small thumbs

Small thumbs are a part of radial longitudinal deficiency- the official name is hypoplastic thumb meaning underdeveloped thumb.  Sometimes this is an isolated problem and sometimes it is associated with abnormalities of the forearm and wrist (radial longitudinal deficiency)-

A small thumb can be on one hand or both but most of the time the hands are not exactly the same (meaning one is worse than the other).  There are 4 main parts to the small thumb: size, stability, and muscle, and motion.
1) As the name implies, the small thumb is small.  It is short and can be thin.
2) It is also unstable at the MCP joint which is the joint (where motion happens) between the thumb and the hand.  The problem with instability at this location is that it affects how you use your hand.  An unstable thumb usually prevents good, strong pinch.
3) The muscles of the thumb are called the thenar eminence.  These muscles are used to position the thumb to allow best function- things like holding a soda can or pinching.  If these muscles are small or absent then the thumb-= the most important of the fingers- can't work correctly.  If the thumb is not working correctly, the patient will have less use of the entire hand.
4) Lastly, a small thumb may have limited motion.  This can be due to the limited muscles or it can be due to abnormal tendons from the forearm- tendons that can have abnormal connections.  The thumb may not bend or straighten well.

The good news about the small thumb is that surgery can be helpful to correct it.  Surgery can make it stronger and more stable and more mobile.  Surgery can never make the thumb normal but it can make a better thumb.  If a thumb is really small, sometimes the thumb may be best treated with pollicization, rather than reconstruction.

If the thumb is reconstructed without pollicization, there are 3 basic steps.  1) Give the thumb more muscle. There are choices for this step but both work well (flexor tendon to ring finger or muscle from pinky side of hand).  2) Make the MCP joint stable  3) Deepen the space between the thumb and index finger, the first web space.  This makes the thumb longer and able to grab larger objects.

These pictures are unusual in that they are of an 11 year old with small thumb or hypoplastic thumbs on both sides.
Small thumbs on both sides.  The left hand (the one on the right side of the picture) is worse- smaller and with less muscle.

This picture is of the child with small thumbs trying to bring the thumbs up.  Neither side does it well.

Another view of the small thumbs trying to lift the thumbs.

Yet another view of small thumbs, attempting to lift.

X-ray of small thumb (the left side) showing a small thumb with unstable joint.

Great x-ray of small thumb, unstable.  Notice the bend in the thumb.

Last picture of small thumbs.  Notice the the left thumb (on the right) is smaller or more angulated than the other one.