What is arthrogryposis?

Arthrogryposis is a condition that a person is born with that does not worsen with age. It includes two or more joint deformities, called contractures, which cause the joint to be fixed in one position. This decreases the ability to move the joint. The muscles and nerves around the joint are often absent, and excess skin over the joint can grow. It is estimated that 1 in 3,000 people have arthrogryposis.

What causes arthrogryposis?

The main cause of arthrogryposis is not known. The leading theory of non-genetic causes is a condition called fetal akinesia that occurs when the fetus is developing. This happens when the fetus does not move around in the womb as much as normal. Joints, muscles and tendons do not form correctly without movement. This causes the joint contractures found in arthrogryposis. More than 35 genetic disorders are associated with arthrogryposis.

What are the symptoms of arthrogryposis?

The symptoms vary with the type and severity of the affected joint.

Symptoms may include:

• Joints that are stuck in abnormal positions.

• Muscles of the affected joint that are weak or absent.

• Increase in skin and fibrous tissue that surrounds the joint.

Any joint can be affected. Sensation around the joint is usually normal.

In very severe cases, respiratory and cardiovascular systems can be involved. This is associated with a poor prognosis but is rare.

What are the types of arthrogryposis?

There are 3 types of arthrogryposis:

1. Amyoplasia or classic arthrogryposis: symmetric, severe joint contractures and muscle weakness. It affects shoulders, elbows, wrists, fingers, hips, knees and feet. It is usually associated with a benign red facial tumor called a hemangioma.

2. Distal arthrogryposis: joint contractures are in mainly the hands or feet.

3. Syndromic: arthrogryposis that is associated with other conditions.

How is the condition diagnosed?

About 50% arthrogryposis cases can be diagnosed before a child is born through imaging procedures such as fetal ultrasound or MRI.

After birth, tests that can be used to make a diagnosis include:

• Biopsy: a sample of tissue is taken and examined more closely to determine its condition.

• Ultrasound: a test that uses sound waves to makes pictures of the inside of the body.

Magnetic resonance imaging (MRI): a test that uses a combination of large magnets, radiofrequencies and a computer to make detailed images of organs and structures within the body.

X-ray: a test that uses invisible electromagnetic energy beams to make images of internal tissues on film.

Computed tomography scan (CT scan): an imaging procedure that uses a combination of X-rays and computer technology to make images of the body.

• Electromyogram and nerve conduction velocity testing: these tests measure the health of nerves and muscles. In an electromyogram, a needle is inserted into a muscle and electrical impulses are recorded. In a nerve conduction test, patches are placed on the skin to record nervous system activity.

What is the treatment for arthrogryposis?

Specific treatment for arthrogryposis will be determined by your child's doctor based on:

• The child's age, overall health and medical history.

• Extent/stage and location of the disease.

• Type of arthrogryposis.

• The child's tolerance for specific procedures or therapies.

• Expectations for the course of the disease.

All treatments aim at increasing joint mobility, muscle strength and functional use of the joint. Treatment may include (alone or in combination):

Physical therapy

Occupational therapy

• Splinting the joint

• Corrective surgery is often used for wrist and hand arthrogryposis:

     o Wrist surgery: The surgeon removes a wedge-shaped piece of bone (called a dorsal carpal wedge osteotomy). This piece causes the abnormal positioning of the hand. Other surgeries can transplant bones from one side of the hand to the other. Tendons can also be transferred to assist the weaker side of the wrist.

     o Thumb surgery: The surgeon removes tight tendons of the thumb (called an index rotation flap). Excess tissue in the space between the thumb and index finger is then used to create a new, wider surface between the thumb and index finger. This allows for increased range of motion of the thumb. 

What is the long-term outlook for a child with arthrogryposis?

Prognosis depends on:

• The extent and type of arthrogryposis.

• Age and overall health of the child.

• The child's tolerance of specific procedures or therapies.

• New developments in treatment.