Types of Arthrogryposis

The recognized definition of Arthrogryposis Multiplex Congentia (AMC) is a condition that causes congenital contractures of two or more body parts. It is important to remember that AMC is not a diagnosis but is an umbrella term that covers over 300-400 different types of conditions and syndromes.

A simple way to categorize this complex issue is:

Amyoplasia

Amyoplasia (A = no, myo=muscle, plasia=growth) means no muscle growth and is the most common type of AMC . It is estimated that one third of people born with AMC will have Amyoplasia about 1 in 10,000 and it’s typically referred to as ‘Classical type AMC.’ This is considered the non-genetic form of AMC, meaning there has been no mutation in the genes to cause the condition to be present, and is not passed down from the parents.

Common traits of people with Amyoplasia are:

  • Affected in both arms and legs, and often the spine
  • Internally rotated shoulders
  • Extended elbows
  • Flexed wrists
  • Contractors of the fingers
  • Lower limbs can be stuck in various positions
  • Hips can have flexion/abduction/external rotational contractures (Buddha position or frog position)
  • Dislocated hips (about 30%)
  • Hip extension contractures (less common)
  • Flexion contractures of the knees
  • Extension contractures of the knees (less common)
  • Club feet
  • About 10% affected individuals may have squashed or missing fingers and toes. (less common)
  • Scoliosis (20-30%)
  • Splotchy red mark on the face (stork bite)
  • About 10% of Amyoplasia cases individuals may have abdominal abnormalities such as gastroschisis. Gastroschisis is a condition in which a hole is present in the wall of the abdomen allowing the intestines to intrude out of the abdominal space. (less common)
  • Normal or above average intelligence

References:

Amyoplasia – Arthrogryposis A Text Atlas. By: Judith G Hall MD, Lynn T Staheli MD, Kenneth M Jaffe MD, Diane O Paholke.

Amyoplaisia Revisited. By: Dr. Judith Hall

Distal

People with distal arthrogryposis (DA) are primarily affected in the hands and feet. Other areas and body functions can be affected depending on what type one has.  There are currently 20+ different types of DA all of which are linked back to genetic mutations. The best way to learn about you or your child’s specific type is to discuss it with health care providers and people in the AMC community. Here are a few of the more common types of distal arthrogryposis.

Type 1:

Type 1 is characterized by joint deformities that restrict movement in the hands and feet.

Common traits of distal type 1 are:

  • Facial sparing
  • Multiple contractures in hands and feet
  • Clenched hands
  • Overlapping fingers
  • A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation
  • Hips and knees can be affected but it is less common and usually mild
  • Club feet

Type 2A (Freeman-Sheldon Syndrome):

Freeman-Sheldon Syndrome primarily affects the hands, feet and face. Distinctive facial features such as a small mouth, with purse lips give the appearance of a whistling face, hence also being called “Whistling Face Syndrome”.

Common traits of Freeman-Sheldon Syndrome are:

  • Prominent forehead and brow ridges
  • Widely spaced eyes
  • Deep set eyes
  • Outside corner of the eyes that point downward
  • Narrowing of the eye openings
  • Droopy eye lids
  • Eyes that do not look in the same direction
  • Sunken appearance of the middle of the face
  • Short nose and a long area between the nose and the mouth
  • Deep folds in the skin between the nose and lips
  • Full cheeks
  • Small mouth with pursed lips
  • Chin dimple shaped like an H or a V
  • Small tongue and jaw and a high arch in the roof of the mouth
  • Difficulty swallowing
  • Multiple contractors in hands and feet
  • A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation.
  • Club feet
  • Spine that curves to the side (scoliosis)
  • Failure to gain weight and grow at expected weight
  • Respiratory complications
  • Speech problems
  • Hearing loss
  • Malignant hyperthermia (MH) is a condition where people have negative reactions to certain drugs used during general anesthesia. If it is of concern you can speak to your doctor about avoiding the use of succinylcholine during general anesthesia.

Type 2B (Sheldon-Hall Syndrome):

Sheldon-Hall Syndrome is similar to Freeman Sheldon Syndrome in that both have joint contractures of various areas of the body. However there are enough differences between the two that they are considered separate conditions.

Common traits of Sheldon-Hall Syndrome are:

  • Triangular shaped face
  • Outside corner of the eyes that point downward
  • Deep folds in the skin between the nose and lips
  • Attached ear lobes
  • Small mouth with pursed lips
  • High arched roof of the mouth
  • Extra folds of skin on the neck
  • Permanently bent fingers and toes
  • Overlapping fingers
  • A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation.
  • Club feet
  • Vertical talus deformity

Type 9 (Beals Syndrome):

Beals syndrome is also known as congenital contractural archnodactyly (CCA) and has many of the same features as Marfan Syndrome. While Beals and Marfan share similar features they are also very distinct in the way they affect a person so it is important to obtain a accurate diagnosis so appropriate treatment can be given.

Common traits of Beals syndrome are:

  • Abnormally shaped ears resulting in a crumpled appearance
  • Unusually small jaw and or high arched palate
  • Abnormal short neck
  • Rounded upper back
  • Chest sinks in or sticks out
  • Long narrow body type with long limbs
  • Abnormally long slender fingers and toes
  • Joints being stuck in a permanent flexed position
  • Contractors in elbows and hands
  • Contractures in feet
  • Club feet
  • Contractures affecting the hips, knees and ankles
  • Curved spine (scoliosis)
  • Backward or lateral curved spine
  • Reduced bone mass
  • Underdeveloped muscles
  • Cardiovascular complications. It is recommended that those with Beals Syndrome have their heart monitored yearly as a precaution because on occasion heart issues like aortic enlargement or mitral valve regurgitation can occur.

References:

Distal type 1 – https://ghr.nlm.nih.gov (Genetics Home Reference)

https://www.disabled-world.com/

Distal type 2A ( Freeman Sheldon) – https://ghr.nlm.nih.gov (Genetics Home Reference)

Malignant Hyperthermia, Coexisting Disorders, and Enzymopathies: Risks and Management Options. By: Joan Benca,MD & Kirk Hogan MD, JD.

Distal type 2B ( Sheldon Hall ) – https://ghr.nlm.nih.gov (Genetics Home Reference)

https://ojrd.biomedcentral.com

Distal type 9 (Beals) – https://rarediseases.org (NORD)

Escobar Syndrome – https://ghr.nlm.nih.gov (Genetics Home Reference)

Everything Else

This category is one of the most complex due to the fact that there are over 250 different diagnosis. Anything that is not Distal or Amyoplasia AMC goes into everything else category.

These include,but not limited too:

  • Pterygium syndromes
  • Lethal conditions
  • Atypical AMC

Pterygium syndromes

Pterygium syndrome is a congenital condition where webbing of the skin occurs around the joints causing a lack of muscle movement which then causes muscle weakness and joint contractures. Escobar syndrome and Lethal multiple pterygium syndrome are a few pterygium syndromes that are connected to AMC. Escobar type multiple pterygium syndrome (Escobar syndrome). There are different types of pterygium syndromes, Escobar being one of the more common types.

Common traits of Escobar syndrome are:

Webbing of the skin that affects

  • Skin on the neck
  • Fingers
  • Forearms
  • Inner thighs
  • Backs of knees

Other Features

  • Droopy eye lids
  • Outside corners of the eyes point downward
  • Skin folds covering the inner corner of the eyes
  • Low set ears
  • Small jaw
  • Arms and legs that cannot fully extend
  • Scoliosis
  • Respiratory distress at birth due to underdeveloped lungs
  • Males can have undescended testes

Lethal multiple pterygium syndrome is tragically individuals with this form of multiple pterygium syndrome typically do not make it past the 2nd or 3rd trimester of pregnancy.

Common traits of Lethal multiple pterygium syndrome are:

  • Abnormally small head
  • An opening in the roof of the mouth which is called cleft palet
  • Fluid filled sac typically found on the back of the neck
  • Excessive fluid in the body
  • Severe multiple contractors
  • Underdevelopment of the heart, lungs, or brain
  • Twisting of the intestines
  • Kidney abnormalities
  • A hole in the muscle that separates the abdomen from the chest cavity

Lethal multiple pterygium syndrome also falls under the Lethal conditions subgroup in the Everything else category.

Lethal Conditions

Tragically it is estimated that 1/3 of babies born with AMC will either be still born or die during their first year of life. There are several forms of AMC that can be deadly. As mentioned above Lethal Multiple pterygium syndrome is one. Another is Cerebro-oculo-facio-skeletal (COFS) as well as Restrictive dermopathy. Cerebro-oculo-facio-skeletal syndrome (COFS) . People with COFS will progressively deteriorate and sadly many times will not survive past 7 years old.

Common traits of COFS can be:

  • Extremely small head
  • Abnormally small eyes
  • Clouding of the eyes lens (cataract)
  • Horizontally narrow opening between the eye lids
  • Unusually prominent nose
  • Abnormally large ears
  • Upper lip over lapping lower lip
  • Abnormally long groove in upper lip
  • Unusually small jaw
  • Elbows with flexion contractures
  • One line in the palm of the hand formed by the fusion of two lines
  • Hip deformities
  • Knees with flexion contractures
  • Congenital vertical talus deformity (rocker bottom)
  • Grove over the length of the soles of the feet
  • Osteoporosis
  • Lack of muscle tone
  • Feeding difficulties
  • Vulnerability to respiratory infections
  • Failure to thrive
  • Developmental retardation

Restrictive dermopathy – Restrictive dermopathy is a lethal genetic skin condition that is connected to AMC. Unfortunately most born with Restrictive dermopathy will not make it past the first week of life.

Common traits of Restrictive dermopathy are:

  • delayed and stunted prenatal growth
  • reduced fetal movements
  • excessive amount of amniotic fluid
  • premature rupture of the membranes
  • thin tight skin
  • translucent skin
  • skin with damage at body parts that bend
  • facial dysmorphism
  • joint ankylosis (stiffness or fixation of joints and/or union of separate bones to
  • form a single bone)
  • death with in the first week of life

Atypical AMC

Atypical AMC is a term used to describe individuals with a unknown type of AMC.  AMC is rare and highly complex and it can take years for certain people to receive the diagnosis that caused AMC, and some may never receive a diagnosis at all. This can be a very long and frustrating journey for many families seeking answers about their loved ones with AMC, or a AMCer seeking answers for themselves.

AMCSI can connect you with support groups, other parents and caregivers through social media, mini-meet ups, and the yearly AMC conference. This will give you an enormous amount of moral support and also ideas for tools and adaptive equipment to help you or your child along.

AMC is a rare condition and it’s important to find an experienced doctor that will effectively treat you or your child. Whether you are Atypical or have a diagnosis you will need treatment and support groups are an excellent place to connect with others who can lead you in the right direction.

Find a Doctor

References:

Lethal multiple pterygium syndrome – https://ghr.nlm.nih.gov (Genetics Home Reference)

Cerebo-oculo-facio-skeletal syndrome – https://rarediseases.org (NORD)

Restrictive Dermopaty – https://www.omim.org

AMCSI is working on expanding the Types of Arthrogryposis page.

We would like to give a special thanks to Dr. Harold Van Bosse MD for helping us with this section.

 

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