Any condition that impairs the movement of the baby while in the womb can result in arthrogryposis multiplex congenita. Such causes may involve
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 Problems With Amniotic Fluid Amniotic fluid is the fluid that surrounds the fetus in the uterus. The fluid and fetus are contained in membranes called the amniotic sac. Problems with amniotic fluid include Too much amniotic... read more
A genetic disorder affecting the baby's ability to move while in the womb, such as muscular dystrophy Introduction to Muscular Dystrophies and Related Disorders Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle structure and function are defective, leading to muscle weakness of varying... read more or a connective tissue abnormality Overview of Connective Tissue Disorders in Children Connective tissue is the tough, often fibrous tissue that binds the body's structures together and provides support and elasticity. Muscles, bones, cartilage, ligaments, and tendons are built... read more
More than 300 genetic disorders (such as spinal muscular atrophy type I Spinal Muscular Atrophies (SMAs) Spinal muscular atrophies are hereditary disorders in which nerve cells that originate in the spinal cord and brain stem degenerate, causing progressive muscle weakness and wasting. The five... read more and trisomy 18 Trisomy 18 Trisomy 18 is a chromosomal disorder caused by an extra chromosome 18 that results in intellectual disability and physical abnormalities. Trisomy 18 caused by an extra chromosome 18. Infants... read more ) have been associated with arthrogryposis multiplex congenita.
(See also Introduction to Birth Defects of the Face, Bones, Joints, and Muscles Introduction to Birth Defects of the Face, Bones, Joints, and Muscles Birth defects of the face and limbs are fairly common. They may involve only a specific body part, such as the mouth (cleft lip or cleft palate) or foot (clubfoot). Or they may be part of a... read more .)
In infants with arthrogryposis multiplex congenita, a number of joints become curved and "frozen" and consequently cannot bend. Many infants have weakened muscles. 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.
A doctor's evaluation
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 Chorionic Villus Sampling Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more or amniocentesis Amniocentesis Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more . Doctors may recommend parents seek genetic counseling.
After birth, doctors do a physical examination and note the baby's frozen joints and limbs. Doctors then do genetic testing by analyzing a sample of the baby's blood to look for chromosome and gene abnormalities. This testing can help doctors determine whether a specific 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 Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (EMG), may be done to help doctors distinguish between various types of arthrogryposis.
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.
Casts and physical therapy
Placing the baby's limbs in a cast and doing physical therapy Physical Therapy (PT) Physical therapy, a component of rehabilitation, involves exercising and manipulating the body with an emphasis on the back, upper arms, and legs. It can improve joint and muscle function, helping... read more 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.