Arthrogryposis Multiplex Congenita (AMC)

What Is Arthrogryposis Multiplex Congenita (AMC)?

Arthrogryposis multiplex congenita (AMC), or arthrogryposis, refers to more than 400 conditions that cause muscles and tendons in certain joints to be too tight. These soft tissues permanently contract or tighten. As a result, a child has stiff joints that move little, if at all. 

“Arthro” is Greek for joints, while “gryposis” means curved or crooked. A child with AMC is born with joints that are in a fixed bent (flexed) or straight (extended) position. AMC affects 1 in 3,000 people. This lifelong condition impairs movements and mobility, but it isn’t painful. Rehabilitative therapies can improve your child’s ability to perform daily tasks and enjoy life to the fullest. In some instances, a child may need surgery.

What Are the Types of Arthrogryposis Multiplex Congenita?

Hundreds of conditions fall under AMC. Some of the more common ones include:

• Amyoplasia: About 1 in 3 children with AMC have amyoplasia (also called classical type AMC). It’s the most common type. The word “amyoplasia” means muscles didn’t develop. It usually affects elbows, wrists, fingers and shoulders. 
• Distal arthrogryposis (DA): There are more than 20 different types of DA. These conditions mostly affect a child’s hands and feet. Freeman-Sheldon syndrome (DA type 2A) and Sheldon-Hall syndrome (DA type 2B) also affect facial muscles and joints, like the jaw. 
• Syndromic arthrogryposis: These conditions affect the chest wall, mouth and internal organs, as well as muscles and joints. Some of the most common ones include Larsen syndrome, Edwards syndrome (trisomy 18) and congenital myotonic dystrophy. 

What Causes Arthrogryposis Multiplex Congenita?

Causes of AMC vary, depending on the type:

• Amyoplasia causes: Experts don’t know what causes amyoplasia. It may occur when a baby doesn’t move enough in the womb due to low amniotic fluid, an unusually shaped uterus or a multiple pregnancy. Extra connective tissue may form around joints. 
• Distal and syndromic arthrogryposis causes: Gene changes (mutations) cause most cases of distal and syndromic arthrogryposis. A child may inherit a changed gene from one parent. Sometimes, the gene change occurs for no known reason. 

What Are the Signs and Symptoms of Arthrogryposis Multiplex Congenita? 

Arthrogryposis affects every child differently. Symptoms depend on the type of disease and severity. The condition tends to affect the same joints on both sides of the body.

Symptoms affecting the limbs may include:

• Bent or straightened joints with limited, movement
• Clubfoot
• Hip dysplasia (dislocated hip)
• Tube-shaped limbs that feel soft or doughy
• Underdeveloped (hypoplastic) muscles
• Webbed skin (pterygium) over the affected joint

Other possible symptoms: 

• Cleft lip and cleft palate
• Developmental delays
• Difficulty swallowing (dysphagia)
• Respiratory infections and problems
• Small mouth or lower jaw

What Are the Complications of Arthrogryposis Multiplex Congenita?

Some children with AMC also have:

• Fetal gastroschisis: Part of a baby’s intestines pokes through an opening in their abdomen. 
• Fetal intestinal atresia: Part of a baby’s intestines doesn’t form properly, causing an intestinal blockage.
• Scoliosis: A child’s spine starts to curve as they get older. 

How Is Arthrogryposis Multiplex Congenita Diagnosed?

In many cases, a prenatal ultrasound detects arthrogryposis while a baby is still in the womb. The ultrasound may take place during routine prenatal care or because an unborn baby isn’t very active.

If your unborn baby has a health concern, you may see maternal-fetal medicine (MFM) doctors who specialize in high-risk pregnancies at The Chicago Institute for Fetal Health. This institute at Lurie Children’s is among a select few comprehensive fetal centers in the country. MFM specialists partner with doctors at Lurie Children’s to provide care from pregnancy to childbirth and beyond.

In some cases, a baby may receive an arthrogryposis diagnosis after delivery if a provider sees joint and limb differences. 

Additional Tests

In some cases, your child’s doctor may recommend additional tests, such as:

• Genetic screening to look for gene mutations that cause distal or syndromic arthrogryposis 
• Imaging tests, such as an ultrasound or CT scan, to look for organ problems that can occur with some types of AMC

How Is Arthrogryposis Multiplex Congenita Treated?

At present, there is no cure for AMC. At Lurie Children’s, our orthopedic doctors customize a treatment plan to help your child be as independent and mobile as possible. We take a team approach to care, bringing together all the specialists your child needs to have the best quality of life. 

Rehabilitative Services

Physical therapy and other rehabilitative services are important treatments for children with arthrogryposis. At Lurie Children’s, we offer comprehensive rehabilitative services, including:

• Physical therapy to gently stretch muscles, improve range of motion and keep muscles from wasting away (atrophy)
• Occupational therapy to improve your child’s ability to complete daily tasks like eating, getting dressed and going to school
• Orthotics and prosthetics to provide custom-fitted splints and braces (orthoses), as needed
• Speech therapy to help with speech, feeding and swallowing problems.

Orthopedic Surgery

In some cases, a child gets a series of casts to reposition a joint (serial casting). If the casts don’t help, your child’s doctor may recommend orthopedic surgery to change a joint’s range of motion. These treatments can help a child use the limb better. However, surgery doesn’t necessarily make the joint more flexible. 

A child may also need surgery to correct a cleft palate, clubfoot, dislocated hip or an organ problem. Children with AMC and clubfoot initially receive the Ponseti method, which is a series of casts and braces. Due to higher rates of recurrence, these children will often need surgery.

What Is Lurie Children’s Approach to Caring for Children With Arthrogryposis Multiplex Congenita?

Orthopedic doctors at Lurie Children’s offer comprehensive care for children with all types of AMC. Your family benefits from:

• AMC specialists: Lurie Children’s is among a select few centers in the region offering specialized care for children with AMC. We have all the experts your child needs to help them lead a full, independent life.
• Full range of rehabilitative services: Our physical, occupational and speech therapists help your child be more independent and mobile. When needed, a child may take part in inpatient rehabilitation at Shirley Ryan AbilityLab.
• Dedicated programs: We have dedicated programs to treat issues associated with AMC. Depending on your child’s needs, they may also see specialists at our Clubfoot Treatment Program, Cleft Lip and Palate Repair Program or Scoliosis Program.
• High-level surgical expertise: Orthopedic surgeries take place at our Level I Children’s Surgery Center. This center has the highest distinction from the American College of Surgeons (ACS), reflecting our commitment to safety and quality.
• Genetic counseling: We offer genetic testing and counseling for families affected by AMC. Our specialists can help you understand how an AMC diagnosis may touch your family and future generations. 
• Support services: Our support services help your family manage a chronic pediatric condition. We have social workers who can help with mental health or financial concerns, and Child Life Specialists who help ease your child’s worries about treatments and tests.

The Division of Orthopedic Surgery and Sports Medicine at Lurie Children’s 

U.S. News & World Report rates Lurie Children’s among the nation’s best for pediatric orthopedic care. Our orthopedic doctors and surgeons have deep expertise in managing complex conditions like AMC. We partner with your family, providing the latest therapies and compassionate care that promote the best quality of life for your child.

Learn more about our Division of Orthopedic Surgery and Sports Medicine