Arthrogryposis Multiplex Congenita
Original Editors - Casey Sisk and Shelby White
- 1 Definition/Description
- 2 Prevalence
- 3 Characteristics/Clinical Presentation
- 4 Associated Co-morbidities
- 5 Etiology/Causes
- 6 Differential Diagnosis
- 7 Diagnostic Tests/Lab Tests/Lab Values
- 8 Medical Management (current best evidence)
- 9 Physical Therapy Management (current best evidence)
- 10 Case Reports/ Case Studies
- 11 Resources
- 12 References
Arthrogryposis Multiplex Congenita (AMC) is a condition that causes a newborn to have stiff, crooked, and contracted joints at birth that causes a loss of range of motion in more than one joint (hands, feet, hips, knees, elbows, shoulders, wrists, fingers, toes, the jaw and the spine). This lack of joint mobility is often accompanied by fibrous ankylosis, which is an overgrowth or proliferation of tissue in the joint.  AMC is a non-progressive condition that is diagnosed at birth.
The primary impairments of children diagnosed with AMC are:
- Decreased joint movement
- Decreased muscle strength and bulk. 
AMC affects roughly 1 in every 3,000 individuals and is a congenital condition present at birth. The condition affects males and females equally throughout its population. The ethnic tendencies are common in the Asian, African and European populations. 
Out of those who have the disease, the incidence of specific deformities are as follows: 
- Clubfoot - 1/500
- Congenital dislocated hips - 1/200 - 1/500
- All congenital contractures - 1/100 - 1/250
- Multiple contractures - 1/3000
Clinical signs and symptoms of AMC include:
- Decreased or absent movement around small and large joints due to contractures
- Muscles of affected limbs are underdeveloped with decreased strength and bulk
- Long bones of the arms and legs are fragile
- Abnormally slender build
- Cleft palate
- Cognition may or may not be affected
- ⅓ of babies affected have structural or functional abnormalities of the CNS
- Usually painless to the child 
Most Typical Presentations of AMC (two common variations of AMC include)
- Flexed and dislocated hips, extended knees, clubfeet, internally rotated shoulders, flexed elbows, and flexed and ulnarly deviated wrists
- Abducted and externally rotated hips, flexed knees, clubfeet, internally rotated shoulder, extended elbows, and flexed and ulnarly deviated wrists 
There are four basic groups that babies born with AMC can be divided into: 
- Those with only limbs affected
- Those with limbs and trunk involvement
- Those with limb, head/face and organ involvement
- Those with limb involvement and severe central nervous dysfunction.
Other classification systems divide patients into three main groups:
- Primarily musculoskeletal involvement;
- Musculoskeletal involvement plus other system anomalies
- Musculoskeletal involvement plus CNS dysfunction and/or mental retardation
The vast majority of individuals affected by AMC enjoy a normal life, living just as long as other adults. However, due to some of the secondary complications such as neurological involvement, or contractures involving the spine or chest wall, there can be more life threatening consequences. In the most serious cases, about 50% of infants that have central nervous system dysfunction in addition to the contractures do not live through their first year. In order to ensure the highest care for these infants, continual monitoring of their respiratory functioning is highly suggested. If they are to contract an upper respiratory infection, this could potentially have life-threatening effects because of the underdeveloped muscles and spinal deformities already present.
Individuals with AMC may also be more susceptible to the respiratory depressant effects of anesthesia because of their muscle weakness, underdevelopment of the lungs or spinal deformities. It is important to inform the Anesthesiologist of your child's diagnosis, even if the surgery has nothing to do with AMC. 
Other possible effects of AMC include:
- Undescended testes
- Eating difficulties due to difficulty swallowing and jaw opening weakness.
- Neurologic abnormalities including epilepsy, defects in neural migration, cerebral hypoplasia, holoprosencephaly, pyramidal tract degeneration, and olivopontocerebellar degeneration. 
- Congenital heart defect 
- Respiratory problems
Etiology/CausesThere are several theories as to the cause of AMC including:
- It is thought to be related to decreased movement in utero which allows for excessive connective tissue to form around the joints. This excessive connective tissue can result in the joint becoming fixed and/or limiting the movement of the joint. Decreased fetal movement can be caused by fetal crowding, secondary to maternal disorders (viral infections, drug use, trauma, or other maternal illness), and low levels of amniotic fluid around the fetus.
- It can be related to multiple factors including genetic and environmental ones 
- Some cases occur as part of a rare, inherited genetic disorders (autosomal recessive, autosomal dominant or x-linked traits) 
- It can be a part of connective tissue disorders
- A common cause can be disorders arriving from the muscles including muscular dystrophy, mitochondrial disorders, myositis, and myopathies. 
AMC requires differentiation from other arthrogryposis types, and approximately 150 other syndromes where stiff joints are a part of the phenotype. Some examples of possible differential diagnoses are as follows: 
- Bony Fusion (symphalangism, coalition, synostosis)
- Contractural arachnodactyly (Beals syndrome)
- Multiple pterygium syndrome
- Lethal multiple pterygium syndrome
- Distal arthrogryposis
- Freeman-Sheldon Syndrome
Diagnostic Tests/Lab Tests/Lab Values
The diagnosis of AMC is most heavily founded based on the clinical examination and evaluation using characteristic symptoms and a detailed patient history. However, there are other tests that can be done to gather a more definite diagnosis including:
- An ultrasound- When there is a lack of fetal mobility and abnormal position in the womb, an ultrasound can help diagnose decreased fetal movement, a common cause of AMC 
- Nerve conduction, electromyography and muscle biopsy can help to determine the underlying cause by diagnosing myopathic or neuropathic disorders. 
- Imaging studies of the central nervous system (CNS)
- Comparative genomic hybridization (CGH) array
- DNA Microarray
- Exome studies
Medical Management (current best evidence)
Surgical management of AMC is not the primary source for treatment. After therapeutic resources (physical therapy, orthotist, OT, SLP, geneticist, etc,) have been utilized, some joint contractures may still persist beyond the level of management these services can offer. This is usually when a surgical option is discussed in order to provide that individual with a better quality of life.
Orthopedic surgery can be done for the joint contractures that are resistant to therapy, stretching and casting. Surgical intervention may include osteotomies (bone cuts) and tendon/ muscle lengthening. Interestingly, a unique trait to this disease, which can add complexity to treatment is that none of the musculoskeletal tissues that are surrounding the contracted joint are normal structurally. If the child does have muscular limitation, tendon transfers have also been performed to improve the length tension relationship and the mechanics of the specific muscle. If a tendon is causing a joint to be held in an abnormal position, a tenotomy can be performed to release the joint from the pull of the tendon. These procedures are usually assisted by capsulotomies as well. One example of soft tissue reconstruction in a child with AMC would be using the pectoralis major muscle as an elbow flexor instead of the contracted biceps muscle to improve function of the UE.
Due to the variability of where the contractures present in each child, other procedures can be carried out according to that body location such as talectomy for equinovarus in the foot. Other research has been conducted on using a femoral-sciatic nerve block through either neurostimulation or ultrasound for distal arthrogryposis cases.
If surgery is being discussed as an option for the child, it is important to consider factors that may affect the outcomes of that procedure. Soft tissue surgery, such as bone and tendon transfers, should be done early in life (ages 3-12 months). Other procedures such as opponensplasty or osteotomies should be performed later in life when the growth of that joint is near completed. With all surgeries, casting and bracing are suggested following these procedures for the best outcomes for the patients. 
Physical Therapy Management (current best evidence)
Physical therapy will be an important component of managing the effects of AMC in patients for the rest of their lives. One of the most important aspects of physical therapy is education, especially for the parents when the child is diagnosed with AMC. The main goal of physical therapy is to maintain maximum function and independence for the patient with AMC, while other goals can include improving joint motion and avoiding further muscle atrophy.
Physical therapy management for patients with AMC can include:
- Gentle joint manipulation
- Management of removable splints for the knees and feet to assist in permitting regular muscle movement 
- Management of orthotics that can assist in gait and independence for children with AMC.
- Serial casting of contracted joints
- Strengthening the patient’s muscles, specifically the hip extensors, quadriceps, and shoulder depressors.
- Stretching of joint and muscle contractures assists in promoting active muscle use to avoid immobilization.
- Assist parents in initiating a stretching program for the family to do at home. It is recommended that stretching be done 3-5 times a day with 3-5 repetitions per set, with each stretch being held 20-30 seconds 
- Aquatic therapy 
- Teaching a patient how to use an assistive device such as a gait trainer, a walker, crutches, orthotics, etc.
- Dynamic strengthening of the trunk
- Ambulation either independently or with an assistive device
- Specifically in infants physical therapy can include: gross motor skills (rolling, sitting, crawling, standing, walking, etc), foot abduction braces, thermoplastic serial splinting, position activities such as stretching the hip flexors and prone positioning, and standing in a standing frame/stander.
Case Reports/ Case Studies
- Kakkad A. Arthrogryposis Multiplex Congenita (AMC): A case report. Indian Journal of Physical Therapy. Indian Journal of Physical Therapy; 2013 [cited 2016Apr11]. Retrieved from: http://indianjournalofphysicaltherapy.in/ojs/index.php/ijpt/article/viewfile/1/2
- Shahrokhi A, Gharib M, Kooshesh MR. A Case Report of Bilateral Upper Extremities Arthrogryposis. Iranian Rehabilitation Journal; 2011 [cited 2016Apr11]. Retrieved from: http://irj.uswr.ac.ir/browse.php?a_code=a-10-100-5
- Sucuoglu H, Ornek N, Caglar C. Arthrogryposis Multiplex Congenita: Multiple Congenital Joint Contractures. Case Reports In Medicine; 2015:379730. doi: 10.1155/2015/379730
- AMCSUPPORT.ORG | Arthrogryposis Multiplex Congenita Support, Inc. Available from: https://www.amcsupport.org/faqsaboutamc.html ( accessed 2 April 2016)
- Campbell SK, Palisano RJ, Orlin MN. Physical therapy for children. 4th ed. St. Louis, MO: Elsevier/Saunders; 2012. p313–32.
- Hall JG. Arthrogryposis Multiplex Congenita - NORD (National Organization for Rare Disorders)Available from: http://rarediseases.org/rare-diseases/arthrogryposis-multiplex-congenita/ ( accessed 10 April 2016)
- Staheli LT. Arthrogryposis: a text atlas. New York: Cambridge University Press; 1998 Available from: http://www.global-help.org/publications/books/help_arthrogryposis.pdf (accessed 10 April 2016)
- Perajit E, Kamolporn K, Ekasame V. Walking ability in patients with arthrogryposis multiplex congenita. Indian Journal Of Orthopaedics. 2014; 48(4): 421-425.
- Kimber E. AMC: amyoplasia and distal arthrogryposis Springer Link. Journal of Children's Orthopaedics; 2015. Available from: http://link.springer.com/article/10.1007/s11832-015-0689-1 (accessed 10 April 2016)
- Chen H. Arthrogryposis Treatment & Management: Medical Care, Surgical Care, Consultations. Medscape; 2015. Available from: http://emedicine.medscape.com/article/941917-treatment#d6 (accessed 10 April 2016)
- Kalampokas E, Kalampokas T, Sofoudis C, Deligeoroglou E, Botsis D. Diagnosing Arthrogryposis Multiplex Congenita: A Review. ISRN Obstetrics & Gynecology. 2012;264918. doi: 10.5402/2012/264918
- Gucev ZS, Pop-Jordanova N, Dumalovska G, Stomnaroska O, Zafirovski G, Tasic VB. Arthrogryposis multiplex congenital (AMC) in a three year old boy: differential diagnosis with distal arthrogryposis: a case report. Cases journal. 2009; 2:9403. doi: 10.1186/1757-1626-2-9403.http://casesjournal.biomedcentral.com/articles/10.1186/1757-1626-2-9403
- Graydon AJ, Eastwood DM. Orthopaedic Management of Arthrogryposis Multiplex Congenita. Springer Link. European Surgical Orthopaedics and Traumatology; 2014 Available from: http://link.springer.com/referenceworkentry/10.1007/978-3-642-34746-7_172 (accessed 10 April 2016)
- Chotigavanichaya C, Ariyawatkul T, Eamsobhana P, Kaewpornsawan K. Results of Primary Talectomy for Clubfoot in Infants and Toddlers with Arthrogryposis Multiplex Congenita. Journal Of The Medical Association Of Thailand = Chotmaihet Thangphaet. 2015; 98 Suppl 8S38-S41.
- Ponde V, Desai A, Shah D, Bosenberg A. Comparison of success rate of ultrasound-guided sciatic and femoral nerve block and neurostimulation in children with arthrogryposis multiplex congenita: a randomized clinical trial. Pediatric Anesthesia. 2013; 23(1): 74-78.
- Bartonek Å. The use of orthoses and gait analysis in children with AMC. Journal Of Children's Orthopaedics. 2015; 9(6): 437-447.