Arthrogryposis (AMC)

Article Translations: (Spanish)

Also called: Arthrogryposis Multiplex Congenita, AMC

What Is Arthrogryposis (AMC)?

Arthrogryposis (ar-throw-grih-POE-sis) is when children have stiffness and loss of motion in more than one joint. Children who have AMC were born with it, and it is usually permanent. But medical experts can help kids get the best range of motion their stiff joints will allow.

What Are the Signs & Symptoms of Arthrogryposis (AMC)?

The joint stiffness that happens with arthrogryposis is called contracture (kun-TRAK-cher). It means the joint can't move the way it should. Joints may stay straight and not bend, or they may stay bent and a child can't straighten them.

Some contractures are mild. Others can be severe. Children may have:

trouble moving
poor growth
weak muscles
very thin or bony-looking arms and legs

Some children have problems in most of their joints. They may have stiff shoulders, elbows, wrists, hands, hips, knees, and feet. Some kids have only a few stiff joints.

When a child has contracture in just one joint (such as clubfoot), it's not usually arthrogryposis.

What Causes Arthrogryposis (AMC)?

Experts don't always know why children have arthrogryposis. It could be something that stops the muscles and joints from developing as they should. Sometimes it's because of another condition, like a disease of the nerves or muscles. Or it might happen because a fetus doesn't have room to move much during pregnancy. This can affect the way the baby's muscles and nerves develop.

With some babies, there's a genetic reason for arthrogryposis. If doctors tell you that your child's condition is genetic, ask if your family should see a genetic counselor.

How Is Arthrogryposis (AMC) Diagnosed?

When a baby is born with more than one contracture, doctors will check the baby's nerves and muscles. They may order blood tests or imaging tests like X-rays.

Doctors sometimes know that a baby has arthrogryposis before birth. That's because it sometimes can show up on a prenatal ultrasound.

Most of the time, doctors can diagnose the problem and plan treatment based on a physical exam and routine tests. Doctors may also need to do tests like these:

nerve conduction studies (NCS) and electromyography (EMG)
muscle or nerve biopsy

How Is Arthrogryposis (AMC) Treated?

Doctors and other medical experts work together as a team to treat arthrogryposis. To help kids get the best range of motion from stiff, tight joints, treatment might include:

bracing and orthotics for joint support
splints and casts to improve joint position and motion
physical therapy and occupational therapy
at-home exercises and stretching to increase strength and flexibility
surgery to reposition bones or move tendons (the cords that connect muscles to the bones)

What Else Should I Know?

Therapy helps kids do the most they can as they grow. Your care team will give you exercises to do with your child at home. It takes time for a child's abilities to improve. Be patient and offer your support to older kids. Parents play a big part in the treatment of arthrogryposis.

Many kids can do things on their own and grow up to be independent. Others need more help. Even when arthrogryposis limits physical abilities, kids usually can think and learn just as well as other kids do.