What is Arthrogryposis Multiplex Congenita?

Arthrogryposis Multiplex Congenita (AMC) occurs in newborns and results in decreased flexibility of the joints. Symptoms differ drastically from person to person, including stiff joints and muscle weakness. The areas that are most likely to have lack of movement are the shoulders, elbows, wrists, hands, hips, knees, and feet. The lack of movement, unlike many other diseases, does not get worse as time goes by. However, it is necessary to seek treatment to prevent further impediments of the joints.

What causes Arthrogryposis Multiplex Congenita?

There are many causes of the condition, some of which are inherited. Before birth, four possibilities exist that limit joint movements:


  1. abnormal development of muscles
  2. inadequate room in the uterus for the baby
  3. a malformed central nervous system and spinal cord
  4. tendons, joints, bones, and joint linings which did not mature correctly

The decrease in range of motion is also caused by extra tissue that has formed around the joint, prohibiting movement. Out of 3000 births, only one is apt to develop AMC, and only 30% of those are genetically related.

How is Arthrogryposis Multiplex Congenita diagnosed?

There are many neuromuscular causes of AMC. Abnormalities can be found in the nerve cells in the spinal cord, the nerves themselves, the junction between the nerve and muscle, and the muscles. Electrodiagnostic testing is helpful to the electrodiagnostic medicine physician in making a diagnosis because it provides information about the function of the nerves and muscles. Information obtained from an electrodiagnostic consultation helps direct the need for any additional testing that may be done in order to make a definitive diagnosis of AMC.

More Information

National Organization for Rare Disorders
National Support Group for AMC

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