What is Arthrogryposis?
Arthrogryposis is a term used to describe a variety of conditions characterized by multiple joint contractures and abnormally developed muscles affecting two or more areas of the body at birth. A contracture occurs when a joint becomes permanently fixed in a straightened or bent position, which can affect joint range of motion and function, and may result in muscle atrophy. In most cases, the condition affects both the arms and legs. However, in severe cases, every joint in the body can be affected, including the back and jaw.
Arthrogryposis is also known as arthrogryposis multiplex congenita (AMC). It is a non-progressive condition that does not worsen with time; however, individuals impacted with it should be treated immediately to prevent further limitation or worsening of joint function.
Types of Arthrogryposis
Arthrogryposis can be differentiated into 4 types:
- Amyoplasia: This is the most common type of arthrogryposis and impacts both the legs and arms. It often results in underdeveloped muscles, deformed joints, and reduced joint range of motion.
- Classic arthrogryposis: This is a severe form of arthrogryposis and impacts almost every joint in the body including the elbows, shoulders, hips, hands, wrists, knees, and feet to varying degrees.
- Distal arthrogryposis: This type impacts only a few joints, normally in the hands and feet, and only marginally affects the range of motion when compared with other types.
- Syndromic arthrogryposis: This type impacts internal organs, as well as joints and muscles. It can cause speech problems, breathing issues, and feeding difficulties in infants. Occasionally, it can also cause developmental delays.
Causes of Arthrogryposis
The exact cause of arthrogryposis is unknown, although it is thought to be associated with decreased fetal movement during development. In general, decreased fetal movement before birth can be attributed to four causes:
- Low amniotic fluid levels and inadequate space in the uterus for normal movement
- Central nervous system malformations
- Abnormally developed tendons, joints, bones, or joint linings
- Abnormal muscle development, muscle disease, or maternal fever during pregnancy
Signs and Symptoms of Arthrogryposis
Some of the signs and symptoms of arthrogryposis include:
- Decreased or absent joint motion due to contractures or stiffness
- Crooked or curved joints
- Underdeveloped muscles in the affected limbs
- Soft tissue webbing on the affected joint
- Decreased strength and bulk
- Cleft palate
- Functional or structural abnormalities of the central nervous system
- Abnormally slender build
- Fragile long bones of the arms and legs
Diagnosis of Arthrogryposis
There is no prenatal test for the diagnosis of arthrogryposis. Abnormalities related to the condition may be discovered during a routine ultrasound, and additional tests will be needed to look for any underlying cause. In general, the diagnostic methods may include:
- A review of medical history and general examination of the clinical findings
- Blood tests, especially genetic workup, to look for a primary cause of the condition
- Muscle biopsies to rule out other conditions or determine a cause
- An electromyography (EMG) study to differentiate between neurogenic and myopathic arthrogryposis
Treatment for Arthrogryposis
There is no permanent cure for this condition. Treatment can only aim at improving quality of life by increasing range of motion and function at the sites of contracture through a multi-disciplinary approach. In general, the treatment may involve:
- Physical and occupational therapy to improve range of motion of affected joints and strengthen muscles to prevent muscle atrophy.
- Orthotics and bracing for joint support
- Casts and splints to increase joint motion and position
- At-home exercises and stretches to improve strength and flexibility
- Neurological evaluation to address fine motor skills
- Psychosocial and emotional care to build a child’s self-esteem and foster independence
- Surgery to transfer tendons or reposition bones to improve muscle function and correct limb contractures, clubfeet, hip dislocations, or other limb deformities that limit or interfere with overall function.