Arthrogryposis multiplex congenita refers to a group of rare disorders that develop in the womb and cause many joints to become "frozen" in position.
Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. "Congenital" means "present at birth." (See also Introduction to Birth Defects of the Face, Bones, Joints, and Muscles.)
Arthrogryposis is a condition in which joints become permanently fixed or "frozen" in position. Frozen joints may be present in more than 300 different disorders, and more than 35 specific genetic disorders (such as spinal muscular atrophy type I and trisomy 18) have been associated with arthrogryposis multiplex congenita.
Causes of Arthrogryposis Multiplex Congenita
Any condition that impairs or limits the movement of a baby while in the womb can result in arthrogryposis multiplex congenita. Examples include
Limitation of the baby's movement, for example, because the mother's uterus is oddly shaped, she is carrying more than one baby, or the amniotic fluid is insufficient
A disorder of the mother, such as multiple sclerosis
A genetic disorder affecting the baby's ability to move while in the womb, such as muscular dystrophy or a connective tissue disorder
Symptoms of Arthrogryposis Multiplex Congenita
In infants with arthrogryposis multiplex congenita, a number of joints become curved and frozen and consequently cannot bend. The muscles attached to the frozen joints are usually weak and poorly developed. Decreased movement of the baby's muscles and joints while in the womb likely cause the decreased movement of the joints after birth. Sometimes the nerves that would normally move the bones in the affected joints are also impaired. Infants with arthrogryposis may also have dislocated hips, knees, or elbows.
Diagnosis of Arthrogryposis Multiplex Congenita
A doctor's evaluation
Genetic testing
Before birth, abnormal limbs may be seen during a routine ultrasound. If abnormal limbs are seen, doctors may do ultrasounds of other parts of the fetus's body or genetic testing on the fetus using chorionic villus sampling or amniocentesis.
After birth, doctors do a physical examination and note the baby's frozen joints and limbs. A baby who has these birth defects may be evaluated by a geneticist. A geneticist is a doctor who specializes in genetics (the science of genes and how certain qualities or traits are passed from parents to offspring). Genetic testing of a sample of the baby's blood may be done to look for chromosome and gene abnormalities. This testing can help doctors determine whether a specific genetic disorder is the cause and rule out other causes.
Tests of the muscles, such as a muscle biopsy (removal of a sample of muscle for examination) and electromyography (EMG), may be done to help doctors distinguish between various types of arthrogryposis.
Prognosis for Arthrogryposis Multiplex Congenita
Babies born with arthrogryposis typically develop relatively normal intelligence, except when the arthrogryposis is caused by a disorder or syndrome that also affects intelligence.
Doctors seek to establish a specific diagnosis for what has caused the arthrogryposis so that parents know what the prognosis is and can receive genetic counseling.
Many children do remarkably well. About two thirds of affected children are able to walk after treatment.
Treatment of Arthrogryposis Multiplex Congenita
Casts and physical therapy
Sometimes surgery
Placing the baby's limbs in a cast and doing physical therapy to carefully move and manipulate the stiff joints may improve joint movements.
Surgery may be needed to free the bones from attached tissue in order to have more normal joint movement. Surgically moving a muscle (for example, moving the triceps muscle so that it can flex rather than extend the elbow) may improve function.
