Amyoplasia

What is amyoplasia?

Amyoplasia occurs when muscle tissue supporting your joints shortens, tightens or wears away. These contractures typically occur in all four limbs. The condition is congenital, meaning it’s present at birth.

Amyoplasia contractures occur when fibrous tissue and fat replace muscle tissue. Over time, joints may bend abnormally and stiffen. These changes decrease flexibility and range of motion.

How can amyoplasia contractures affect my child?

Amyoplasia is the most common type of arthrogryposis multiplex congenita (AMC). This group of conditions affects two or more joints and is present at birth. Amyoplasia is also known as classic arthrogryposis or amyoplasia congenita.

A child with amyoplasia may have severely deformed joints. Contractures may become permanent, preventing your child from using their affected limb. These contractures can affect your child’s ability to perform basic tasks, such as sitting and walking. But getting your child moving early and regularly can prevent contractures from becoming rigid.

What types of contractures occur with amyoplasia congenita?

Amyoplasia can cause:

• Abduction: A contracture that moves parts away from your body’s midline. Hip abduction moves your upper leg away from your pelvis.
• Extension: A joint extends, creating a wide angle or straight line with the two body parts it connects. Knee extension straightens your leg.
• Flexion: When a joint bends, creating a sharp angle. Elbow in flexion brings your hand inward, near your upper body.
• Dislocation: Bones near a joint slip out of position. A dislocated shoulder happens when your upper arm bone slips out of the groove in your shoulder blade.
• Rotation: Circular movement of a joint such as the shoulder. Rotation may cause your shoulders to turn inward, taking on a slumped position.

What causes amyoplasia?

Researchers aren’t sure what causes amyoplasia congenita. It’s not genetic, which means the condition isn’t due to a gene mutation. It also doesn’t run in families.

What are the symptoms of amyoplasia?

A child may show symptoms all over their body, including the:

Lower extremities

Symptoms affecting your child’s hips, legs and feet may include:

• Clubfoot.
• Heel pain due to a missing heel pad, which is a thick layer of tissue in the soles of the feet.
• Hip dislocation, flexion or abduction contracture.
• Knee flexion or extension contracture.

Upper extremities

Symptoms affecting your child’s shoulders, arms and hands include:

• Elbow extension contracture.
• Finger abduction.
• Rigid thumb extension.
• Shoulder rotation contracture.

Skin

Amyoplasia can also affect your child’s skin, leading to:

• Dimpling.
• Lack of creases over the joints.
• Stork bite, a common facial birthmark.
• Vascular malformation (abnormal blood vessel formations) on the face, such as hemangioma.
• Webbing near the elbows or knees.

Are there other symptoms I should be aware of?

Amyoplasia congenita can also lead to issues elsewhere in the body, but these aren’t common.

Rare symptoms include:

• Bowel atresia, in which part of the intestines does not develop correctly or is missing.
• Gastroschisis, when the intestines exit the body from a small hole in the belly button.
• Hypoplasia of the labial folds in females, folds of skin of the vagina are small or missing.
• Inguinal hernia.
• Micrognathia, a small or recessed jaw.
• Missing fingers or toes.
• Scoliosis.
• Undescended testicles in males.

How is amyoplasia congenita diagnosed?

Amyoplasia is often diagnosed during a physical exam, which helps identify contractures. Additional testing with standard X-rays helps healthcare providers determine the severity.

What amyoplasia treatments might my child need?

In the early stages, amyoplasia treatment focuses on:

• Optimizing range of motion.
• Preventing pain and muscle wasting (atrophy).
• Easing contractures.

Your child may benefit from:

• Physical therapy: Gentle stretching and massage that help lengthen muscle fibers. Exercise stimulates blood flow to muscles and joints.
• Occupational therapy: Involves guiding your child through tasks that work fine motor skills. These exercises help your child complete daily activities.
• Splinting: A rigid and removable device that holds a joint in a fixed position.
• Serial casting: A series of casts that support the joint and gradually intensify stretching for up to six weeks.

What other amyoplasia treatments are available?

For more advanced forms of the disease, a surgical procedure may be necessary:

• Muscle transfer: Surgeons replace nonfunctioning muscle tissue with healthy tissue from another area of the body.
• Osteotomy: Surgeons remove a segment of bone to improve the range of motion in a nearby joint.

Can you walk with amyoplasia?

Your child’s ability to walk depends on the type of contracture. Severe knee flexion contracture may prevent your child from walking. Many, but not all, children with severe hip flexion contractures also might not be able to walk. Special devices, such as a standing frame, braces, walkers and crutches can help them keep walking.

Can I prevent amyoplasia?

Because researchers don’t know what causes amyoplasia, there is nothing you can do to prevent it.

What is the prognosis for people with amyoplasia?

Children with amyoplasia typically live a normal lifespan. The condition does not affect a child’s ability to think and learn, making it possible to go to school.

What’s helpful to know about living with amyoplasia?

By age 5, most children are walking and fully participating in daily activities. Intensive physical and occupational therapy after birth is essential to achieving these outcomes.

Special devices and techniques can also optimize your child’s independence. These include:

• Adaptive utensils that curve to the side or strap on to the wrist help children feed themselves.
• Chair inserts make it safe and comfortable for your child to sit.
• A hook attached to the lower portion of a wall can help children pull pants up or down.

A note from Cleveland Clinic

With amyoplasia, muscle tissue supporting certain joints shortens or tightens. This leads to contractures that make movement difficult. Early amyoplasia treatment with physical therapy and serial casting can slow contracture progression. Many children end up needing multiple surgeries. Special devices and techniques, along with occupational therapy, can maximize your child’s independence, even when contractures are severe.