Sunday, February 26, 2017

The Hand in Multiple Epiphyseal Dysplasia

Multiple Epiphyseal Dysplasia (MED) is an uncommon anomaly of the bone and cartilage at the ends of the bones (epiphyses) in the growing child.  There are 6 primary types of Multiple Epiphyseal Dysplasia. All are transmitted in an autosomal dominant fashion except type 4.

EDM1 is caused by a heterozygous mutation in the gene encoding cartilage oligomeric matrix protein              (COMP).  Most common.
EDM2 -a mutation in the COL9A2 gene
EDM 3 -a mutation in the COL9A3 gene
EDM 4 -a mutation in the DTDST gene.  This type is autosomal recessive whereas the others are                      autosomal dominant. 
EDM5 -a mutation in the MATN3 gene
EDM6 -a mutation in the COL9A1 gene

Historically, the more severe type of Multiple Epiphyseal Dysplasia was known as the Fairbank type (dominant) while the more mild form was known as the Ribbing type.  The Ribbing type was thought to have normal or more normal wrist and hands.   These terms are no longer utilized.

The abnormal epiphysis at the bone ends leads to progressively worsening ossification and this causes joint abnormalities often leads to stiff joints and arthritis.  Onset varies by the particular type- more severe types present earlier with childhood pain, often in the hip or knees but also potentially involving the hands and wrists. The fingers may be short and stiff.

The diagnosis is based on a clinical suspicion but it can be a challenging diagnosis which is based on the patient’s history and examination.  An experienced orthopedic surgeon or radiologist may detect x- ray changes- this experience is the key to making the diagnosis.  The diagnosis may be confirmed by genetic testing as noted above.

There is no current treatment to prevent worsening or change the course of Multiple Epiphyseal Dysplasia.  Ultimately, there is a future potential for genetic intervention.  Currently, hand or physical therapy may be helpful to maintain motion and surgery can be helpful to contour the bone and joints and improve motion and decrease pain. 

This is the case of an 8 year old child with Multiple Epiphyseal Dysplasia.  I met the patient to assess the hands and wrists which had been stiff since a young age.  There was discomfort with daily activities but the biggest issue was related to function given the finger stiffness (present for many years).  The clinical pictures demonstrate the finger posture (most notably PIP joint stiffness)  and the x- rays confirm loss of joint spaces.

Multiple Epiphyseal Dysplasia hand clinical photograph with stiffness of multiple joints

Multiple Epiphyseal Dysplasia hand side- view clinical photograph with stiffness of multiple joints

Multiple Epiphyseal Dysplasia hand x- ray

Charles A. Goldfarb, MD
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Sunday, February 19, 2017

The Crooked Thumb

The process of limb development is truly amazing and unbelievably complex.  Developmental biologists and scientists help to explain these processes and our knowledge grows day by day.   As I explain to parents, what is truly remarkable is not that there is a child born with a limb difference but rather that it happen so uncommonly.  One such uncommon finding is a crooked finger, or for the purposes of this post, a crooked thumb.

In my experience, the most common cause of a crooked thumb is an extra bone which creates a triphalangeal thumb.  I have previously written about the type of thumb HERE.  Typically, there are two bones in the thumb but, like fingers, there can occasionally be three bones- the TRIphalangeal thumb.  This can occur in association with an extra thumb (see HERE) or in isolation.  Not every triphalangeal thumb is crooked- the alignment depends on the shape of the extra bone.

When the extra bone is triangular in shape, the thumb is crooked and can affect function.  Typically, surgery to remove that bone (or straighten it) is performed.  In doing so, the thumb is shortened as well.  When the extra bone is more normally shaped- rectangular- then the thumb is not crooked and a decision for surgery is more complex.  For some kids, the long thumb may not be a problem but for others, the length of the thumb + the extra joint can cause functional issues.

This 18- month old came to the office because of a crooked thumb.  Mom had noticed some difficulty with pinching and decreased use of the thumb.  Here are pictures and x-rays which demonstrate the deformity.

Crooked thumb related to an extra bone- a triphalangeal thumb.

Crooked thumb related to an extra bone- a triphalangeal thumb.  It is more difficult to see in this side- view picture.

The extra bone can be seen in the x- ray causing the thumb to be crooked.
The extra bone in this thumb is more difficult to see in this x- ray.

Surgery to address the crooked thumb addresses the extra bone.  A recent investigation carefully evaluated the best way to surgically treat this condition.  The authors evaluated excision of the extra bone compared to angular correction and fusion of one of the joints- the results were similar.  New Article.

The are other causes of a crooked thumb in a child.  These include the small thumb, or hypoplastic thumb- I have posted numerous times on this TOPIC.  Another cause is less likely in the newborn but common in childhood- a thumb fracture which can classically lead to deviation.

The bottom line is that the crooked thumb can be both a functional and an appearance issue.  Surgery can effectively correct this issue.

Charles A. Goldfarb, MD
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