CONGENITAL SYNOSTOSIS

CONGENITAL RADIAL-ULNAR SYNOSTOSIS

INTRODUCTION:

                       Synostosis, or osseous union, of any two adjacent bones can involve any part of the upper extremity. In 1793, Sandifort provided the initial description of congenital radial-ulna synositis. This condition is caused by a failure of segmentation between the radius and the ulna. Synositis between the radius and ulna can take two general forms: Congenital and post-traumatic 

v  Forearm begins as a single cartilaginous and divides from distal to proximal into the radius and ulna in the 7th week in utero.

v  Failure of differentiation results in synostosis in proximal aspect of the forearm.

v  60% of the cases are BILATERAL.

v  Male are more affected than Female (3:2)

ANATOMY;

  

SIGNS AND SYMPTOMS:

Ø  Painless

Ø  Most commonly asymptomatic, noticed by parents and teachers.

Ø  Can notice or identify difficulty with specific movements/tasks

v  Keyboard, table-top activities – Deficient Pronation.

v  Eating, washing face, catching a ball – Deficient Supination.

CLASSIFICATION:

                Wilkie divided congenital synostosis into the following two types on the basis of the proximal radio-ulnar junction:

Ø  Type 1 - Complete synostosis has occurred, with the radius and ulna fused proximally for a variable distance

Ø  Type 2 - Less involved, and may exist as a partial union; this type involves the region just distal to the proximal radial epiphysis and is associated with radial head dislocation

          Cleary and Omer described four types of congenital synostosis, as follows:

Ø  Fibrous synostosis

Ø  Bony synostosis

Ø  Associated posterior dislocation of the radius

Ø  Associated anterior dislocation of the radius

Simmons considered congenital synostosis to be a spectrum of anomalies in which the synostosis occurred in varying lengths, with or without involvement of the radial head.

EXAMINATION AND TEST:

Ø  Average age of diagnosis is 6 years of age

v  Can go unnoticed until early adolescence, especially in unilateral cases

Ø  Elbow flexion usually preserved

Ø  Fixed forearm pronation

v  Average position is 30° of pronation

Ø  Compensatory motion

v  Shoulder abduction - compensates for loss of active pronation

v  Shoulder adduction - compensates for loss of active supination

v  Wrist hypermobility. 

DIAGNOSTIC METHOD:

Ø  X-ray

Normal x-ray of elbow:

X-ray changes in Congenital Radial-Ulna Synosytis:

   

     

Ø  CT-scan (in rare cases advised)

TREATMENT:

Ø  Non-Surgical Method:

        Observation is the preferred treatment, particularly when asymptomatic and unilateral.

Ø  Surgical Method:

v  Indication is when absolute deformity is limiting ability to participate in specific activities and movements.

v  Surgery is indicated when relative severe pronation deformity > 60^o  with bilateral deformities.  

v  Osteotomy – to improve static forearm and hand movements.

                Doctor decides the treatment according to the severity by monitoring the changes and type according to the classification.

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