Arthrogryposis refers to when a baby is born with one or more joints featuring a contracture at birth. A contracture is when a joint is permanently stuck in an extended or flexed position, which can completely or partially restrict its movement.
Following a diagnosis of arthrogryposis, a healthcare team can provide various treatment options to help improve the mobility and strength of the joint. While the life expectancy of someone with the condition depends on the severity of the syndrome and its effect on their joints, it typically does not affect their life span.
In this article, we will discuss arthrogryposis, including its causes, symptoms, and more.
Arthrogryposis, also known as arthrogryposis multiplex congenita (AMC), is a descriptive term. It refers to the development of multiple joint contractures that affect two or more areas of the body before birth. A contracture refers to where a joint becomes permanently fixed in an extended (straightened) or flexed (bent) position. It may result in partial or complete restricted movement in the affected joint.
- amyoplasia, also known as classic arthrogryposis, which affects the shoulders, elbows, wrists, fingers, hips, knees, and feet
- distal arthrogryposis, which mainly occurs in the hands or feet
- syndromic arthrogryposis, which can affect internal organs as well as the muscles and joints
Estimates suggest that AMC affects fewer than 50,000 people in the United States. That works out to about 1 in 3,000 live births. AMC is a congenital condition, meaning it is present from birth. While doctors do not know the exact cause of AMC, some researchers suggest the condition is genetic or hereditary.
AMC is not a progressive disorder, which means it will not worsen over time. Doctors, surgeons, physical therapists, and other medical team members can often help a baby correct the contractures and go on to live typical lives.
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The overall prognosis will depend on the severity of a person’s symptoms, the joints involved, and the therapies they receive. Someone with AMC will generally have a typical life span.
AMC is not a specific medical condition. The exact cause can vary according to the subtype of AMC a baby develops. Some researchers believe the underlying causes of AMC may be genetic or hereditary. Possible causes for AMC may include:
- obstructions to intrauterine movement during pregnancy
- early viral infection during a baby’s development
- when the central nervous system, muscular system, or both cannot develop appropriately
Symptoms can vary in severity, which joints are involved, and how many joints are involved. The most common symptom of AMC is absent or limited movement in the small and large joints present at birth. Often, the muscles around the joint are underdeveloped and feel soft and doughy.
AMC also has links to other symptoms, which can include:
- dislocated hips
- facial asymmetry
- facial birthmarks
- internally rotated shoulders and limbs
- intestinal, kidney, bladder, and genital problems
- muscle absence or atrophy
- respiratory problems
- scoliosis, an atypically curved spine
- webbed skin, dimpled skin, or both
Diagnosis typically occurs early in a baby’s life. A doctor can often make a diagnosis of AMC according to:
- the identification of characteristic symptoms, such as the presence of multiple contractures at birth
- a detailed patient and parent medical history review
- a clinical evaluation of the baby
In some cases, a doctor may order tests to determine the underlying nature of the condition, such as whether it is due to nerves or muscle conditions. Tests they may use can include:
- nerve conduction
- a muscle biopsy
A doctor may also order additional imaging of the central nervous system and genetic studies to determine the underlying cause and help with diagnosis.
Treatment will vary according to the affected joints. It typically involves a multidisciplinary approach to help each child achieve a typical life. Some common forms of treatment include:
- ongoing physical therapy
- stretching and strength-building exercises
- using removable splints and braces
- serial casting to improve joint mobility
- surgically correcting joints to improve mobility and help with tendons
- occupational therapy
- therapies to address emotional development, such as psychotherapy
Arthrogryposis is a general term that describes joint contractures that can occur due to various underlying causes. These contractures can cause complete or partially restricted movement of affected joints. It is a rare condition that affects a relatively small number of people in the United States.
AMC is present at birth, and a person typically receives a diagnosis early in life. Therapies are typically multidisciplinary and include methods to help a child gain more joint and muscle strength and mobility. While the severity of the condition can vary, a person with arthrogryposis typically has a typical life span.