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Arthrogryposis multiplex congenita

Arthrogryposis, Congenital multiple arthrogryposis, Fibrous ankylosis of multiple joints, Myodystrophia fetalis deformans, Congenital arthromyodysplasia

Overview

Arthrogryposis multiplex congenita (AMC), describes congenital joint contractures in two or more areas of the body. It derives its name from Greek, literally meaning "curving of joints" (arthron, "joint"; grȳpōsis, late Latin form of late Greek grūpōsis, "hooking"). Children born with one or more joint contractures have abnormal fibrosis of the muscle tissue causing muscle shortening, and therefore are unable to perform passive extension and flexion in the affected joint or joints. A contracture occurs when a joint becomes permanently fixed in a bent or straightened position, which can impact the function and range of motion of the joint and may lead tomuscle atrophy. AMC is not a specific diagnosis, but rather a physical symptom that can be associated with many different medical conditions. AMC has been divided into three groups: amyoplasia, distal arthrogryposis, and syndromic. Amyoplasia is characterized by severe joint contractures and muscle weakness. Distal arthrogryposis mainly involves the hands and feet. Types of arthrogryposis with a primary neurological or muscle disease belong to the syndromic group.

Classification:

Some of the different types of AMC include:

  • Arthrogryposis multiplex due to muscular dystrophy.
  • Arthrogryposis ectodermal dysplasia other anomalies, also known as Cote Adamopoulos Pantelakis syndrome, Trichooculodermovertebral syndrome, TODV syndrome and Alves syndrome.
  • Arthrogryposis epileptic seizures migrational brain disorder.
  • Arthrogryposis IUGR thoracic dystrophy,also known as Van Bervliet syndrome.
  • Arthrogryposis like disorder, also known as Kuskokwim disease.
  • Arthrogryposis-like hand anomaly and sensorineural deafness.
  • Arthrogryposis multiplex congenita CNS calcification.
  • Arthrogryposis multiplex congenita distal (AMCD), also known as X-linked spinal muscular atrophy type 2
  • Gordon Syndrome, also known as Distal Arthrogryposis, Type 2A.
  • Arthrogryposis multiplex congenita, distal type 2B, also known as Freeman-Sheldon syndrome variant.
  • Arthrogryposis multiplex congenita neurogenic type (AMCN). This particular type of AMC has been linked to the AMCN gene on locus 5q35. Arthrogryposis multiplex congenita pulmonary hypoplasia, also with a large number of synonyms.
  • Arthrogryposis multiplex congenita whistling face, also known as Illum syndrome.
  • Arthrogryposis multiplex congenita, distal type 1 (AMCD1).
  • Arthrogryposis ophthalmoplegia retinopathy, also known as Oculomelic amyoplasia.
  • Arthrogryposis renal dysfunction cholestasis syndrome, also known as ARC Syndrome

Symptoms - Arthrogryposis multiplex congenita

Arthrogryposis multiplex congenita (AMC) refers to the development of multiple joint contractures affecting two or more areas of the body prior to birth. A contracture occurs when a joint becomes permanently fixed in a bent or straightened position, which can impact the function and range of motion of the joint. In some cases, only a few joints are affected and the range of motion may be nearly normal. In people who are severely affected, every joint in the body can be involved, including the jaw and back.  Muscles of affected limbs may be atrophied or underdeveloped. Soft tissue webbing may develop over the affected joint.

AMC is not a specific diagnosis, but rather a physical symptom that can be found in many different medical conditions. The signs and symptoms associated with AMC can, therefore, vary greatly in range and severity depending on the underlying condition.

  • Abnormality of the gastric mucosa
  • Abnormality of the hip bone
  • Abnormality of the pleura
  • Abnormality of the wrist
  • Aplasia/Hypoplasia of the lungs
  • Congenital diaphragmatic hernia
  • Depressed nasal ridge
  • Low-set, posteriorly rotated ears
  • Lymphedema
  • Polyhydramnios
  • Scoliosis
  • Talipes
  • Ulnar deviation of finger

Causes - Arthrogryposis multiplex congenita

It is suspected that AMC is related to decreased fetal movement during development which can have a variety of different causes, including environmental factors (i.e. maternal illness, limited space), single gene changes (autosomal dominant, autosomal recessive, X-linked), chromosomal abnormalities and various syndromes. In principle: any factor that curtails fetal movement can result to congenital contractures. The exact causes of arthrogryposis are unknown yet.

Extrinsic factors:

The malformations of AMC can be secondary to environmental factors such as: decreased intrauterine movement, oligohydramnios (low volume or abnormal distribution of intrauterine fluid), and defects in the fetal blood supply. Other causes could be: hyperthermia, limb immobilization and viral infections. Myasthenia gravis of the mother leads also in rare cases to arthrogryposis. The major cause in humans is fetal akinesia. However, this is disputed lately.

Intrinsic factors

AMC could also be caused by intrinsic factors. This includes molecular, muscle- and connective tissue development disorders or neurological abnormalities.

Molecular basis:

Research has shown that there are more than 35 specific genetic disorders associated with arthrogryposis. Most of those mutations are missense, which means the mutation results in a different amino acid. Other mutations that could cause arthrogryposis are: single gene defects (X-linked recessive, autosomal recessive and autosomal dominant), mitochondrial defects and chromosomal disorders (for example:trisomy 18). This is mostly seen in distal arthrogryposis. Mutations in at least five genes (TNN12, TNNT3, TPM2, MYH3 and MYH8) could cause distal arthrogryposis. There could be also connective tissue-, neurological of muscle development disorders.

Muscle and connective tissue developement disorders:

Loss of muscle mass with an imbalance of muscle power at the joint can lead to connective tissue abnormality. This leads to joint fixation and reduced fetal movement. Also muscle abnormalities could lead to a reduction of fetal movement. Those could be: dystrophy, myopathy and mitochondrial disorders. This is mostly the result of abnormal function of the dystrophin-glycoprotein-associated complex in the sarcolemma of skeletal muscles.

Neurological abnormalities:

70-80% of the cases of AMC are caused by neurological abnormalities. Most of these result from an underlying genetic syndrome, or are due to environmental factors.

The underlying aetiology and pathogenesis of congenital contractures, particularly arthrogryposis and the mechanism of the mutations remains an active area of investigation. Because identifying these factors could help to develop treatment and congenital finding of arthrogryposis.

Prevention - Arthrogryposis multiplex congenita

Not supplied.

Diagnosis - Arthrogryposis multiplex congenita

There is currently a lot of research on prenatal diagnosis. The diagnosis can be made prenatally in approximately 50% of fetuses presenting arthrogryposis. It could be found during routine ultrasound scanning showing a lack of mobility and abnormal position of the foetus. Nowadays there are more options for visualization of details and structures can be seen well, like the use of 4D ultrasound. In clinic a child can be diagnosed with arthrogryposis with physical examination, confirmed by ultrasound, MRI, or muscle biopsy.

Prognosis - Arthrogryposis multiplex congenita

The prognosis is not well defined and therefore it is difficult to search, because of the small number of patients. But there are a few factors that seem to have an influence on the prognosis like the progressive muscle activity improvement. Results of a study showed an increase in strength during growth after the recovery of a passive range of motion in a useful arc. Other positive prognostic factors for independent walking were active hips and knees, hip flexion contractures of less than 20 degrees and knee flexion contractures less than 15 degrees without severe scoliosis.

Treatment - Arthrogryposis multiplex congenita


Treatment varies based on the signs and symptoms found in each person, but may include physical therapy, removable splints, exercise, and/or surgery. The primary long-term goals of these treatments are increasing joint mobility, muscle strength and the development of adaptive use patterns that allow for walking and independence with activities of daily living. Since arthrogryposis includes many different types, the treatment varies between patients depending on the symptoms. Only a few good articles exist in which a surgical technique that is used to treat arthrogryposis is described.

These surgeries are explained below.

Wrist surgery:

Children with the amyoplasia type of arthrogryposis usually have flexed and ulnarly deviated wrists. Dorsal carpal wedge osteotomy is indicated for wrists with excessive flexion contracture deformity when non-surgical interventions such as occupational therapy and splinting have failed to improve function. On the dorsal side, at the level of the midcarpus, a wedge osteotomy is made. Sufficient bone is resected to at least be able to put the wrist in a neutral position. If the wrist is also ulnarly deviated, more bone can be taken from the radial side to correct this abnormality. This position is held into place with two cross K-wires. In addition, a tendon transfer of the extensor carpi ulnaris to the extensor carpi radialis brevis may be performed to correct ulnar deviation or wrist extension weakness, or both. This tendon transfer is only used if the extensor carpi ulnaris appears to be functional enough.

Thumb surgery:

The soft tissue envelope in congenital contractual conditions such as clasped or arthrogrypotic thumbs is often deficient in two planes, the thumb-index web and the flexor aspect of the thumb. There is often an appearance of increased skin at the base of the index finger that is part of the deformity. This tissue can be used to resurface the thumb-index web after a comprehensive release of all the tight structures to allow for a larger range of motion of the thumb. This technique is called the index rotation flap. The flap is taken from the radial side of the index finger. It is proximally based at the distal edge of the thumb-index web. The flap is made as wide as possible, but still small enough to close with the excessive skin on the palmar side of the index finger. The flap is rotated around the tightest part of the thumb to the metacarpophalangeal joint of the thumb, allowing for a larger range of motion.

Other surgeries:

Many other surgeries are also able to improve function in joints of arthrogryposis patients. These surgeries usually exist out of tendon transfers and skin flap movements, adjusted to the individual.

Resources - Arthrogryposis multiplex congenita

  • NIH
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