Arthrogryposis: Causes, Symptoms, Treatment, and Prognosis

Arthrogryposis or arthrogryposis multiplex congenita (AMC) is the name given to a group of disorders characterized by the development of multiple joint contractures throughout the body. A contracture is a condition where a joint becomes stiff and fixed in a bent or straight position, causing restrictions in the movement of that joint.

The condition develops before birth (it is a congenital defect) and in the U.S., it occurs about once per every 3,000 to 5,000 live births, affecting both males and females of all ethnic backgrounds.

More than one body part has to be affected for the disorder to be referred to as arthrogryposis. If a congenital contracture occurs only in one area of the body (such as the feet, a condition called clubfoot) then it is an isolated congenital contracture and not arthrogryposis.

When two or more different areas of the body are affected by arthrogryposis, the condition may be referred to as arthrogryposis multiplex congenita (AMC) and sometimes both names are used interchangeably. There are more than 150 types of AMC, with amyoplasia being the most common and accounting for more than 40% of all AMC cases.

Arthrogryposis is usually caused by decreased fetal movements in the womb. The fetus needs movement in the limbs to develop muscle and joints. If the joints don't move, extra connective tissue develops around the joint and fixes it in place. Some of the causes of decreased fetal movements are:

• Malformations or malfunctions of the central nervous system (most common cause), such as spina bifida, brain malformations, or spinal muscular atrophy
• An inherited neuromuscular disorder such as myotonic dystrophy, myasthenia gravis, or multiple sclerosis
• Maternal infections during pregnancy such as German measles (rubella) or rubeola
• Maternal fever above 39C (102.2F) for an extended period, or increased maternal body temperature caused by prolonged soaking in hot tubs
• Maternal exposure to substances that can harm the fetus, such as drugs, alcohol, or an anti-seizure medication called phenytoin (Dilantin)
• Too little amniotic fluid or chronic leaking of amniotic fluid may cause reduced space for the fetus to move around

The particular joint contractures found in an infant with arthrogryposis vary from child to child, but there are several common characteristics:

• The legs and arms are affected, with wrists and ankles being the most deformed (think of the fetus folded up inside the uterus, then locked in that position)
• The joints in the legs and arms may not be able to move at all
• Muscles in the legs and arms are thin and weak or even absent
• The hips may be dislocated

Some infants with arthrogryposis have facial deformities, a curvature of the spine, genital deformities, cardiac and respiratory problems, and skin defects.

There is no cure for arthrogryposis, and treatment is directed towards specific symptoms an individual may be experiencing. For example, early vigorous physical therapy can help stretch out the contracted joints and develop the weak muscles. Splints can also help stretch joints, especially at night. Orthopedic surgery may also be able to relieve or correct joint problems.

Ultrasound or computed tomography (CT) scan can identify any central nervous system abnormalities. These may or may not require surgery to treat. Congenital heart defects may need to be repaired.

The lifespan of an individual with arthrogryposis is usually normal but may be altered by heart defects or central nervous system problems. In general, the prognosis for children with amyoplasia is good, though most children require intensive therapy for years. Almost two-thirds are eventually able to walk (with or without braces) and attend school.