Arthrogryposis

What is arthrogryposis?

Arthrogryposis is a term doctors use to describe joints that are stiff and fixed in a bent or straightened position from birth. The word comes from Greek roots meaning “curved” or “hooked” joints. When two or more joints in different parts of the body are affected, the condition is usually called arthrogryposis multiplex congenita (often shortened to AMC). “Multiplex” means many joints, and “congenita” means present at birth.

Arthrogryposis is not a single disease. It is a physical sign that can appear in a large number of different conditions. The one feature they share is a contracture, which is a joint that cannot move through its normal range because the muscles, tendons, or joint capsule around it are shortened or tight. The most common form of arthrogryposis is called amyoplasia, meaning “no muscle growth,” in which some muscles are replaced by fibrous or fatty tissue and the limbs are affected in a fairly typical pattern.

Arthrogryposis is rare. It affects boys and girls, and in most cases it is noticed at birth or on an ultrasound scan during pregnancy. Because the range of underlying causes is wide, the outlook varies a great deal from one child to another. Many children with arthrogryposis have normal intelligence, especially in amyoplasia, although some rarer forms are linked to conditions that also affect the brain or other organs.

Arthrogryposis symptoms

The main sign of arthrogryposis is one or more joints that are stuck in a fixed position at birth. The pattern and severity depend on the type. Common arthrogryposis symptoms and features include:

• Joints that cannot bend or straighten fully, most often in the hands, wrists, elbows, shoulders, hips, knees, and feet
• Thin, tube-shaped limbs with less muscle bulk than expected
• Missing or shallow skin creases over the affected joints, because the joint has not been moving before birth
• Small dimples in the skin over some joints
• Clubfoot (a foot turned inward and downward), which is very common
• Shoulders turned inward, elbows held straight, wrists bent downward, and fingers curled, in the pattern often seen in amyoplasia
• Hips that are stiff, bent, or dislocated
• A curved spine (scoliosis), which may be present at birth or develop later
• In some children, a small jaw, a narrow mouth, or difficulty feeding

In amyoplasia, the limbs are usually affected on both sides of the body in a fairly symmetric way, and a flat red birthmark in the middle of the forehead is common. The trunk, face, and internal organs are typically spared, and thinking and learning are usually normal.

In the group of conditions called distal arthrogryposis, the stiffness mainly affects the hands and feet, and the large joints are often normal or only mildly involved. Some distal types also include features such as a small mouth, an unusual facial appearance, or a short neck.

When arthrogryposis is part of a syndrome, meaning a wider pattern of problems with one underlying cause, children may also have differences in the brain, heart, kidneys, breathing muscles, or development. In these cases the joint stiffness may be only one part of a broader picture.

Arthrogryposis is generally not painful in infants, because the joints have never moved in the affected direction. Pain can become an issue later in life if joints wear unevenly or if muscles are strained by compensating movements.

Causes and risk factors

Arthrogryposis causes all come back to one process: the baby did not move enough in the womb. Joints develop normally in early pregnancy, but they need regular movement to stay flexible. When a developing baby’s limbs stay still for weeks or months, extra connective tissue forms around the joints, the joint surfaces change shape, and the muscles that are not used stay small. Doctors call this lack of movement fetal akinesia.

Many different problems can reduce fetal movement. They are usually grouped as follows:

• Nerve problems. Conditions affecting the brain, spinal cord, or the nerves that supply the muscles can stop the signals that make a baby move. This is thought to be the most common group.
• Muscle problems. Some forms of inherited muscle disease or muscle that never developed properly leave the baby too weak to move.
• Connective tissue problems. Abnormal tendons, joint capsules, or skin can physically hold joints in place.
• Limited space in the womb. Too little amniotic fluid, a womb of unusual shape, large fibroids, or a multiple pregnancy can restrict movement.
• Maternal illness or exposures. Certain infections, high fever, some medications, and maternal conditions that affect nerve-to-muscle signaling have been linked to reduced fetal movement.
• Poor blood supply. A temporary interruption in blood flow to the developing limbs or spinal cord is thought to play a role in amyoplasia.

Amyoplasia, the most common form, occurs by chance. It is not inherited, and the risk of it happening again in a future pregnancy is thought to be very low. By contrast, many distal arthrogryposis types and some syndromic forms are caused by changes in specific genes and can run in families. Some are passed on in a dominant pattern, meaning one copy of the altered gene is enough, while others require a copy from each parent.

Known risk factors include a family history of arthrogryposis or of an inherited nerve or muscle condition, low amniotic fluid during pregnancy, a twin or multiple pregnancy, and certain maternal illnesses. In a large share of cases, however, no clear risk factor is ever identified.

Diagnosis

Arthrogryposis is often first suspected during pregnancy. On a routine ultrasound, the sonographer may notice that the baby moves very little, that the limbs stay in the same position over time, or that the hands or feet are held in unusual postures. Low amniotic fluid can be another clue. In these situations a more detailed scan and, sometimes, an MRI of the baby may be recommended.

After birth, the diagnosis of arthrogryposis itself is made by physical examination. A doctor checks each joint’s range of motion, looks for missing skin creases and dimples, assesses muscle bulk, and notes the overall pattern of which joints are stiff and in which direction. Because arthrogryposis is a sign rather than a single disease, the more important task is to find out what is causing it, and this may involve:

• X-rays of the affected joints, hips, and spine to check bone shape, joint alignment, and dislocations
• Genetic testing, ranging from targeted tests for known genes to broader panels or whole-exome sequencing, which reads the protein-coding parts of all genes
• Neurological assessment, and in some cases an MRI of the brain and spinal cord, to look for problems with the nervous system
• Electromyography (EMG) and nerve conduction studies, which measure the electrical activity of muscles and nerves
• Muscle biopsy, in which a small piece of muscle is removed and examined under a microscope, if a muscle disease is suspected
• Blood tests, including tests for muscle enzymes or for infections
• Assessment of the heart, kidneys, breathing, and feeding when a wider syndrome is a possibility

A clinical geneticist, a specialist in inherited conditions, is often involved to look at the whole pattern and advise on whether the condition could recur in future pregnancies. In many cases a specific underlying diagnosis is found, but in some children the cause remains unknown even after thorough testing.

Treatment options

There is currently no treatment that reverses the underlying cause of arthrogryposis. The aim of arthrogryposis treatment is instead to improve joint position and movement, build strength, and help the child do everyday tasks as independently as possible. Care is usually shared among several specialists, including pediatric orthopedic surgeons, physical and occupational therapists, rehabilitation doctors, and geneticists. At Acibadem, this care is coordinated through the Orthopedics & Joint Center together with pediatric and rehabilitation teams.

Early stretching and positioning. Treatment often begins in the first weeks of life, when tissues are most flexible. Parents are usually taught gentle stretching exercises to perform several times a day. This early phase can make a meaningful difference to how much later treatment is needed.

Splints, braces, and casts. Custom-made splints hold a joint in an improved position between stretching sessions. Serial casting, in which a cast is changed every one to two weeks to gradually move the joint, is commonly used for clubfoot and for stiff knees or elbows. Braces, called orthoses, may be worn during the day or at night to maintain gains.

Physical and occupational therapy. Physical therapy focuses on large movements such as sitting, standing, and walking. Occupational therapy focuses on hand use and daily skills such as feeding, dressing, and writing, and may include adaptive tools. Therapy typically continues, in some form, throughout childhood.

Surgery. When stretching and casting do not achieve enough improvement, surgery may be considered. Procedures depend on the joint and may include releasing or lengthening tight tendons and joint capsules, cutting and realigning bone (an osteotomy), transferring a working muscle to do the job of a missing one, or correcting hip dislocation. Clubfoot may need surgery if casting alone is not enough. Surgery for scoliosis is sometimes needed in later childhood. Surgeons generally weigh the benefit of a better joint position against the risk that a joint may become stiffer after an operation, and timing is planned around the child’s growth.

Medication. No medicine treats arthrogryposis itself. Pain relievers may be used after surgery, and children with an underlying condition such as a muscle disease may receive treatment directed at that condition.

Adaptive equipment and support. Wheelchairs, walkers, modified utensils, and computer tools can increase independence. Speech, feeding, and breathing support may be needed in syndromic forms. Psychological support and contact with other families are often valuable for both children and parents.

Living with arthrogryposis and outlook

The outlook depends mainly on the underlying cause. For children with amyoplasia and most distal types, life expectancy is usually normal, and intelligence is typically unaffected. With early and consistent treatment, many children learn to walk, with or without braces, and most develop ways to feed themselves, write, and manage personal care, sometimes using techniques that look different from the usual way of doing things.

For children whose arthrogryposis is part of a condition affecting the brain, breathing muscles, or other organs, the outlook is more variable and is shaped by those other problems more than by the joints themselves.

Arthrogryposis does not get worse over time in the sense of spreading to new joints. However, contractures can return as a child grows if stretching and bracing are stopped, and joints that have been shaped differently since birth may develop wear, stiffness, or pain in adolescence and adulthood. Regular follow-up with an orthopedic team through the growing years, and sometimes into adult life, is usually recommended. Many adults with arthrogryposis work, drive with adaptations, live independently, and raise families.

Frequently asked questions

Is arthrogryposis multiplex congenita a genetic condition?

Sometimes. Amyoplasia, the most common form, is not inherited and happens by chance, so the risk to future children is thought to be very low. Distal arthrogryposis and many syndromic forms are caused by gene changes and can be passed down. A geneticist can review the specific pattern and test results and advise on recurrence risk for a particular family.

Can arthrogryposis be detected before birth?

Often, yes. Reduced fetal movement and fixed limb positions may be seen on ultrasound, sometimes as early as the second trimester, though milder forms can be missed. If arthrogryposis is suspected, additional scans, a fetal MRI, or genetic testing may be offered. A prenatal suspicion does not always tell doctors the exact cause, which is usually clarified after birth.

What are the first arthrogryposis symptoms parents notice?

The most obvious early signs are limbs held in unusual, fixed positions, such as feet turned inward, wrists bent down, or elbows that will not bend. Parents may also notice thin arms or legs, absent skin creases at the joints, or small dimples in the skin. These findings are usually confirmed by a doctor’s examination in the first days of life.

Does arthrogryposis treatment cure the condition?

No treatment cures arthrogryposis, because the joint changes occurred before birth. However, stretching, splinting, casting, therapy, and, when needed, surgery can improve joint position and function significantly in many children. The goal is practical independence rather than completely normal joints, and results vary from child to child.

Will my child with arthrogryposis be able to walk?

Many children with arthrogryposis do learn to walk, sometimes with braces or other aids, especially when the hips and knees respond well to treatment. Others use a wheelchair for some or all of their mobility. Your child’s team can give a more individual picture based on the joints involved, muscle strength, and response to early treatment.

What causes arthrogryposis in an otherwise healthy pregnancy?

In many cases no clear cause is found. Arthrogryposis causes all involve reduced movement of the baby in the womb, which can result from nerve or muscle problems in the baby, limited space, or a temporary drop in blood supply to the developing limbs. Most cases are not the result of anything a parent did or did not do.

Is arthrogryposis painful?

In babies and young children, arthrogryposis is usually not painful, because the joints have never moved in the restricted direction. Stretching and casting can cause some temporary discomfort. In adolescence and adulthood, uneven joint wear or muscle strain from compensating movements may lead to pain, which can often be managed with therapy, supportive devices, or medical care.

When to see a doctor

Arthrogryposis is usually identified at birth or during pregnancy, and ongoing care is planned by the child’s medical team. Even so, there are situations in which prompt medical attention is important. Seek urgent care if a child with arthrogryposis has:

• Difficulty breathing, blue or gray color around the lips, or pauses in breathing, especially in infants
• Choking, gagging, or an inability to feed safely
• A cast that feels very tight, with toes or fingers that are swollen, pale, blue, cold, numb, or very painful
• A fever or foul smell coming from a cast or a surgical wound, or redness and discharge around an incision
• Sudden new pain, swelling, or loss of movement in a joint that was previously stable
• Signs of a hip or other joint dislocation, such as a leg that suddenly looks shorter or turned
• A fall or injury involving a stiff limb, since bones near fixed joints can break more easily
• New weakness, loss of skills the child previously had, or changes in alertness

Contact the child’s regular doctor or specialist team in a non-urgent way if stretching exercises seem to be causing increasing pain, if a splint or brace no longer fits or causes skin sores, if a joint seems to be losing motion that had been gained, or if a curve in the spine appears to be getting worse. Regular scheduled follow-up remains important throughout childhood, even when things appear stable.