Arthrogryposis

Arthrogryposis Multiplex Congenita (AMC)
Other names	Arthrogryposis
Specialty	Orthopedics, Pediatrics
Symptoms	Congenital joint contracture in two or more body areas
Complications	Mobility issues, muscle shortening
Causes	Genetic and environmental factors, limited fetal movement
Diagnostic method	Physical examination, genetic testing
Treatment	Physical therapy, orthopedic surgeries
Frequency	Rare

Arthrogryposis

Lee Pearson, born with arthrogryposis and a 10-times paralympic games gold medallist

Arthrogryposis Multiplex Congenita (AMC), commonly known as arthrogryposis, is a medical condition that describes congenital (present at birth) joint contracture in two or more areas of the body. The term is derived from the Greek words "arthron" which means "joint" and "grȳpōsis" which refers to "hooking" or "curving".

Overview

Individuals with AMC are born with joint contractures, meaning they have stiff joints and cannot move them as freely as they should. This is due to an abnormal fibrosis of the muscle tissue which leads to muscle shortening, preventing active extension and flexion in the affected joints.

Classification

Arthrogryposis can be categorized into three main groups:

• Amyoplasia: This is the most severe form, characterized by joint contractures and muscle weakness.
• Distal Arthrogryposis: Mainly affects the hands and feet.
• Syndromic: Types of arthrogryposis that are linked with primary neurological or muscle diseases.

Signs and Symptoms

While it's possible for all joints in a patient with arthrogryposis to be affected, studies have found that:

• 84% of cases involve all limbs.
• 11% affect only the legs.
• 4% involve only the arms.

Typical signs, depending on the joint affected, include:

• Shoulder: Internal rotation.
• Wrist: Volar and ulnar deviations.
• Hand: Fixed flexion of fingers and thumb positioned within the palm.
• Hip: Flexed, abducted, and externally rotated, with potential for dislocation.
• Elbow: Extended and pronated.
• Foot: Clubfoot.

The joint contractures observed in patients can delay walking development within the first five years of life.

Intelligence is typically normal to above average in children with the amyoplasia form of arthrogryposis. However, some individuals with AMC may present with other syndromes or diseases, which might affect various organs. Common associated conditions include pulmonary hypoplasia, cryptorchidism, congenital heart defects, tracheoesophageal fistulas, inguinal hernias, cleft palate, and eye abnormalities.

Causes

The exact causes of arthrogryposis remain elusive, but research indicates that any factor restricting fetal movement can lead to congenital contractures. Potential causes can be broadly divided into extrinsic and intrinsic factors:

Extrinsic Factors:

• Limited intrauterine movement.
• Oligohydramnios (low amniotic fluid).
• Defects in fetal blood supply.
• Elevated maternal body temperature.
• Limb immobilization.
• Viral infections during pregnancy.
• Maternal conditions like Myasthenia gravis.
• Fetal akinesia.

Intrinsic Factors:

• Genetic mutations causing more than 35 specific genetic disorders associated with arthrogryposis.
• Abnormalities in muscle and connective tissue development.
• Neurological disorders.

Research and Future Directions

Understanding the underlying causes and mechanisms of arthrogryposis is crucial for developing effective treatments. Ongoing research aims to investigate the exact molecular basis, potential genetic mutations, and the role of both intrinsic and extrinsic factors in the development of the condition.

See Also

• Joint Contracture
• Congenital Disorders
• Muscle Hypoplasia
• X-linked spinal muscular atrophy type 2

Arthrogryposis Resources
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