Arthrogryposis

Congenital defect of the joints

Arthrogryposis is the name given to a group of disorders characterized by multiple joint contractures throught the body present at birth. In the U.S., it occurs about once per every 3,000 live births, and affects both males and females of all ethnic backgrounds.

Causes
Arthrogryposis is usually caused by decreased fetal movements in the womb. The fetus needs to move his/her 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 dystropy, myasthenia gravis, or multiple sclerosis
• Maternal infections during pregnancy such as German measles (rubella) or rubeola
• Maternal fever above 39 C (102.2 F) 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 phenytoin (Dilantin)
• Too little amniotic fluid, or chronic leaking of amniotic fluid, may cause reduced space for the fetus to move around

Symptoms
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, 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, curvature of the spine, genital deformities, cardiac and respiratory problems, and skin defects.

Treatment
There is no cure for arthrogryposis, but 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.

Prognosis
The life span for an individual with arthrogryposis is usually normal, but may be altered by heart defects or central nervous system problems.

Information for this article was taken from:
Chen, H. Arthrogryposis. eMedicine, accessed at http://www.emedine.com/ped/topic142.htm