Arthrogryposis Multiplex Congenita

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74 Arthrogryposis multiplex congenita comprises nonprogres- sive conditions characterized by multiple joint contractures throughout the body at birth. The term encompasses a very het- erogeneous group of disorders having the common feature of multiple congenital joint contractures. The frequency is approx- imately 1 in 3000 live births.

GENETICS/BASIC DEFECTS

1. Major causes

a. Arthrogryposis as a physical sign observed in many specific clinical conditions

i. Single gene defects

ii. Chromosomal abnormalities

iii. Known or unknown syndromes or conditions iv. Environmental effects

b. Fetal akinesia due to fetal abnormalities

i. Neurogenic abnormalities: the most common cause of arthrogryposis

a) Meningomyelocele b) Anencephaly c) Hydranencephaly d) Holoprosencephaly e) Spinal muscular atrophy

f) Cerebrooculofacial-skeletal syndrome g) Marden-Walker syndrome

ii. Muscular abnormalities: relatively rare causes of arthrogryposis

a) Congenital muscular dystrophies b) Congenital myopathies

c) Intrauterine myositis d) Mitochondrial disorders

iii. Connective tissue abnormalities in tendon, bone, joint, or joint lining restricting fetal movements, resulting in congenital contractures. Examples include:

a) Synostosis

b) Lack of joint development

c) Aberrant fixation of joints (as in diastrophic dysplasia and metatropic dwarfism)

d) Aberrant laxity of joints with dislocations (as in Larsen syndrome)

e) Aberrant soft tissue fixations (as in popliteal pterygium syndrome)

f) Failure of normally developed tendon to attach to the appropriate place around the joint or bone in some forms of distal arthrogryposis, resulting in abnormal lack of movement of the joints with secondary contractures at birth iv. Mechanical limitations to movement. Limited space for fetal movement inside the uterus may contribute to development of contractures.

Examples include:

a) Multiple births

b) Uterine structural abnormalities such as bicornuate uterus

c) Umbilical cord wrapping

d) Oligohydramnios in renal agenesis e) Early persistent leakage of amniotic fluid v. Intrauterine vascular compromise resulting in

loss of nerve and muscle function with development of fetal akinesia and secondary joint contractures. Examples include:

a) Severe maternal bleeding during pregnancy b) Failed attempts at termination of pregnancy c. Fetal akinesia due to maternal disorders. Examples

include:

i. Infections a) Rubella b) Poliomyelitis ii. Drugs/chemicals

a) Methocarbamol b) Alcohol

c) Carbon monoxide poisoning iii. Trauma

iv. Vitamin deficiency

v. Hyperthermia (e.g., prolonged sauna) vi. Radiation

vii. Other maternal illnesses a) Maternal autoantibodies b) Diabetes mellitus c) Myotonic dystrophy d) Maternal multiple sclerosis 2. Pathophysiology

a. Joint development

i. Almost always normal during early embryogen- esis

ii. Fetal motion essential for normal development of joints and their contiguous structures

b. Lack of fetal movement

i. Causing extra connective tissue to develop around the joint

ii. Resulting in fixation of the joint

iii. Limiting movement further aggravates the joint contracture

iv. Contractures secondary to fetal akinesia: more severe in patients who are diagnosed early in pregnancy and who experience akinesia for longer periods of time during gestation

CLINICAL FEATURES

1. Family history

a. Presence of congenital contractures in the family i. Affected siblings

ii. Other affected family members

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b. Marked intrafamilial variability i. Mildly affected parent

ii. A parent with contractures early in infancy c. Consanguinity

i. Increasing the chance that the parents will both carry the same disease gene

ii. Observed more frequently in families with rare recessive diseases than in those with common recessive diseases

d. Increased parental age

i. Some chromosomal abnormalities: increasing dramatically with advanced maternal age ii. Single-gene dominant mutations: increasing

with advanced paternal age

e. History of previous miscarriages or stillbirths 2. Pregnancy history

a. Diminished fetal movement

b. Infants born to mothers affected with the following disorders:

i. Myotonic dystrophy: a child who inherits the gene and is severely affected with resistant contractures

ii. Myasthenia gravis and multiple sclerosis: children may be born with congenital contractures c. Maternal infections leading to CNS or peripheral

nerve destruction with secondary congenital contractures

i. Rubella ii. Rubeola iii. Coxsackievirus

iv. Enterovirus v. Akabane

d. Maternal fever or hyperthermia causing contractures due to abnormal nerve growth or migration

e. Exposure to teratogens leading to decreased fetal movement

i. Drugs ii. Alcohol iii. Curare

iv. Methocarbamol v. Phenytoin vi. Radiation

f. Amniotic fluid volume

i. Oligohydramnios: causes fetal constraint and secondary deformational contractures

ii. Polyhydramnios: indicating fetal compromise g. Uterine abnormalities

i. Bicornuate uterus with a septum ii. Uterine fibroid

h. Other maternal complications i. Toxemia

ii. Severe hypotension at critical time

iii. Severe hypoxia (e.g., carbon monoxide poisoning) during pregnancy

iv. Abnormal fetal lies v. Threatened abortion vi. Attempted termination

vii. Trauma such as trauma to the abdomen 3. Delivery history

a. Breech or transverse fetal position

i. Relatively common

ii. Usually normal length of gestation iii. Induction of labor often prolonged

iv. Fracture of a limb during traumatic delivery in 5–10% of cases

b. Abnormal placenta, membranes, or cord insertion in case of amniotic bands or vascular compromise. The umbilical cord may be shortened or wrapped around a limb, leading to compression

c. Prematurity

d. Multiple births or twins

i. Lack of movement due to uterine crowding ii. The death of one twin may lead to vascular com-

promise in the remaining twin 4. Common physical characteristics

a. Involved extremities

i. Fusiform or cylindrical in shape ii. Thin subcutaneous tissue iii. Absence of skin creases b. Deformities

i. Usually symmetric ii. Severity increasing distally

iii. Hands and feet typically being the most deformed

c. Joint rigidity

d. Associated joint dislocations, especially the hips and, occasionally, the knees

e. Muscles i. Atrophy ii. Absence f. Sensation

i. Usually intact

ii. Diminished or absent deep tendon reflexes 5. Contractures

a. Distal joints affected more frequently than proximal joints

b. Types of contractures i. Flexion vs extension

ii. Limitation of movement (fixed vs passive vs active)

iii. Complete fusion vs ankylosis and soft-tissue contracture

c. Intrinsically derived contractures

i. Frequently associated with polyhydramnios ii. Symmetric contractures

iii. Accompanied by taut skin iv. Pterygia across joints

v. Lack of flexion creases

vi. Recurrence risk and prognosis dependent on etiology

d. Extrinsically derived contractures

i. Associated with positional limb anomalies, large ears, loose skin, and normal or exaggerated flexion creases

ii. Excellent prognosis iii. A low recurrence risk 6. Deformities

a. Limb deformities

i. Pterygium (webbing) ii. Shortening

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iii. Amniotic bands

iv. Compression (e.g., due to cord wrapping) v. Absent patella

vi. Dislocated radial heads vii. Dimples

b. Face deformities i. Asymmetry ii. Flat nasal bridge iii. Hemangioma

iv. Jaw deformities including micrognathia and trismus c. Other deformities

i. Scoliosis

ii. Genital deformities a) Cryptorchidism b) Microphallus c) Lack of labia iii. Hernias

a) Inguinal b) Umbilical

d. Other features of the fetal akinesia sequence i. Intrauterine growth retardation

ii. Pulmonary hypoplasia iii. Craniofacial anomalies

a) Hypertelorism b) Cleft palate c) Depressed nasal tip d) High nasal bridge

iv. Functional short gut with feeding problems v. Short umbilical cord

e. Absent or distorted crease abnormalities resulting from aberrant form or function in early hand or foot development

7. Malformations

a. Craniofacial malformations i. CNS

a) Structural malformations b) Seizures

c) Mental retardation ii. Skull

a) Craniosynostosis b) Asymmetry c) Microencephaly iii. Eyes

a) Small and malformed eyes b) Corneal opacities

c) Ptosis d) Strabismus iv. Palate

a) High-arched b) Cleft

c) Submucous cleft

b. Respiratory problems affecting lung function i. Tracheal and laryngeal clefts and stenosis ii. Hypoplasia or weak muscles of diaphragm c. Limb malformations

i. Reduction anomalies ii. Radioulnar synostosis iii. Syndactyly

iv. Shortened digits

d. Skin/vasculature abnormalities

i. Hemangiomas and cutis marmorata ii. Cold and blue distal limbs

e. Cardiac problems

i. Congenital heart defects ii. Cardiomyopathy

f. Urogenital structural anomalies i. Kidneys

ii. Ureters iii. Bladder

g. Nervous system problems i. Loss of vigor ii. Lethargy

iii. Slow, fast, or absent deep tendon reflexes iv. Sensory deficits

h. Muscle malformations i. Decreased muscle mass ii. Soft muscle texture iii. Fibrous bands

iv. Abnormal tendon attachments v. Muscle changing with time 8. Connective tissue abnormalities

a. Skin webs (pterygia) across joints with limitation of movement

b. Skin dimples observed frequently over joints where movement is limited

c. Soft, doughy, thick, or extensible skin d. Decreased or increased subcutaneous fat e. Inguinal, umbilical, or diaphragmatic hernias

f. Thickness in joints g. Symphalangism

h. Abnormalities in tendon attachment and length i. Associated skin defects including scalp defects,

amniotic bands on limbs, and nail defects 9. Disorders with mainly limb involvement

a. Amyoplasia

i. The most common type of arthrogryposis seen in clinical practice and constitutes about one-third of cases

ii. Incidence: about 1 in 10,000 live births

iii. A sporadic condition, not observed in siblings or offspring (recurrence risk not increased) iv. Characterized by typical and symmetric posi-

tioning of the limbs

v. Internally rotated and adducted shoulders vi. Fixed extended elbows

vii. Pronated forearms viii. Flexed wrists and fingers

ix. A severe talipes equinovarus deformity

x. Muscles: hypoplastic and usually replaced by fibrous and fatty tissue

xi. Normal intelligence b. Distal arthrogryposes

i. Type I: an autosomal dominant disorder characterized by medially overlapping fingers, tightly clenched fists at birth, ulnar deviation of fingers and camptodactyly in adults, and positional foot contractures. Intelligence is usually normal

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ii. Type II (Freeman-Sheldon syndrome, also known as whistling face syndrome): an autosomal dominant disorder characterized by a masklike face with a small mouth, giving a whistling face appearance, deep-set eyes, small nose with a broad nasal bridge, epicanthal folds, strabismus, high arched palate, small tongue, an H-shaped cutaneous dimpling on the chin, flexion of fingers, equinovarus feet with contracted toes, and kyphoscoliosis

iii. Type III (Gordon syndrome): characterized by short stature (90%), cleft palate, bifid uvula, epicanthal folds, congenital ptosis, short neck, and camptodactyly

iv. Type IV (scoliosis)

v. Type V (ophthalmoplegia, ptosis) vi. Type VI (sensorineural hearing loss) vii. Type VII (trismus pseudocamptodactyly) viii. Type VIII (autosomal dominant multiple ptery-

gium syndrome)

ix. Type IX (congenital contractural arachnodactyly):

an autosomal dominant disorder characterized by joint contractures, a long, thin body builds, crumpling ears but lacking cardiovascular and ocular abnormalities of Marfan syndrome c. Bony fusion likely to be confused with arthrogryposis

i. Symphalangism (e.g., fusion of phalanges) ii. Coalition (e.g., fusion of the carpals and tarsal

bones)

iii. Synostosis (e.g., fusion of long bones) d. Other associated syndromes and conditions

i. Absence of dermal ridges

ii. Absence of distal interphalangeal joint (DIP) creases

iii. Amniotic bands iv. Antecubital webbing

v. Camptodactyly

vi. Congenital clapsed thumbs

vii. Familial impaired pronation and supination of forearm

viii. Humeroradial synostosis ix. Liebenberg syndrome

x. Nail-patella syndrome

xi. Nievergelt-Pearlman syndrome xii. Poland anomaly

xiii. Radioulnar synostosis xiv. Tel-Hashomer camptodactyly

10. Disorders with involvement of limbs and other body parts a. Multiple pterygium syndrome

i. Autosomal recessive type: characterized by multiple joint contractures with marked pterygia, dysmorphic facies (flat, sad, motionless facial appearance), and cervical vertebral anomalies ii. Autosomal dominant type: characterized by

multiple pterygia with or without mental retardation

b. Multiple pterygium syndrome (pterygia with flexion contractures) associated with scoliosis, cleft palate, and malignant hyperthermia

c. Multiple pterygium syndrome, Escobar type i. Webbing of the neck that increases with age ii. Webbing of the knees and elbows that develops

before adolescence iii. Multiple joint contractures

iv. Lumbar lordosis

d. Lethal multiple pterygium syndrome i. An autosomal recessive disorder ii. Early lethality

iii. Hydrops fetalis iv. Cystic hygroma

v. Dysmorphic facies (hypertelorism, markedly flattened nasal bridge with hypoplastic nasal alae, cleft palate, micrognathia, low-set ears) vi. Marked webbing and flexion contractures of

multiple joints vii. Short neck viii. Small chest

ix. Hypoplastic lungs e. Popliteal pterygium syndrome

i. An autosomal dominant disorder ii. Popliteal webs

iii. Cleft lip or palate iv. Webs in the mouth

v. Unusual nails

f. Lethal popliteal pterygium syndrome (Bartsocas- Papas syndrome)

i. An autosomal recessive disorder ii. Severe webs across the knee

iii. Associated with facial clefting and fused digits (synostosis of the hand and foot bones) in the newborn period

iv. Usually lethal

g. Osteochondrodysplasias known to be associated congenital contractures

i. Camptomelic dysplasia

ii. Conradi-Hünermann (chrondrodysplasia punctata) iii. Diastrophic dysplasia

iv. Focal femoral dysplasia v. Geleophysic syndrome vi. Kniest dysplasia

vii. Metaphyseal dysplasia, Jansen type viii. Metatropic dysplasia

ix. Larsen dysplasia x. Nail-patella syndrome xi. Oculodentodigital syndrome xii. Orocraniodigital syndrome xiii. Osteogenesis imperfecta type II

xiv. Otopalatodigital syndrome xv. Parastremmatic dysplasia

xvi. Perinatal lethal osteogenesis imperfecta xvii. Pfeiffer syndrome

xviii. Saul-Wilson syndrome xix. Synspondylism

xx. Spondyloepiphyseal dysplasia congenita xxi. Otospondylometaepiphyseal dysplasia h. Other associated syndromes and conditions

i. Hand-muscle wasting and sensorineural deafness ii. Holt-Oram syndrome

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iii. Kuskokwim syndrome iv. Leprechaunism

v. Megalocornea with multiple skeletal anomalies vi. Möbius syndrome

vii. Nemaline myopathy

viii. Ophthalmomandibulomelic dysplasia

ix. Prader-Willi habitus/osteoporosis/hand contractures

x. Pseudothalidomide syndrome xi. Puretic-Murray syndrome xii. Sacral agenesis

xiii. Schwartz-Jampel syndrome xiv. Sturge-Weber syndrome

xv. Tuberous sclerosis

xvi. VATER (vertebral defects, imperforate anus, tracheoesophageal fistula, radial and renal dysplasia) complex

xvii. Weaver syndrome xviii. Winchester syndrome

xix. X-trapezoidocephaly with midfacial hypoplasia and cartilage abnormalities

11. Disorders with limb involvement and CNS dysfunction a. Associated chromosome abnormalities

i. Sex chromosome anomalies (45,X, 47,XXY/

48,XXXY, 49,XXXXX, 49,XXXXY)

ii. Autosomal trisomies (4p, 8, 8 mosaicism, 9, 9q, 10p, 10q, 11q, 13, 14, 15, 18, 21)

iii. Other chromosome anomalies b. Cerebro-oculofacio-skeletal syndrome

i. A common lethal condition ii. Contractures

iii. Brain anomalies iv. Dysmyelination v. Microphthalmia vi. Cataracts vii. Renal anomalies viii. Other visceral anomalies c. Neu-Laxova syndrome

i. A lethal autosomal recessive disorder ii. Dramatic contractures

iii. Intrauterine growth retardation iv. Microcephaly

v. Open eyes

vi. Tight ichthyotic skin vii. Severe CNS anomalies d. Restrictive dermopathy

i. A lethal autosomal recessive disorder

ii. Contractures and failure of fetal skin to grow normally restricting fetal movement and leading to secondary contractures

e. Pena-Shokeir phenotype: Phenotype is caused by fetal akinesia rather than a specific syndrome

i. Short, fixed limbs ii. Pulmonary hypoplasia iii. Intrauterine growth retardation

iv. Polyhydramnios v. Short umbilical cord vi. Unusual craniofacies

12. Other associated syndromes and conditions a. Adducted thumbs

b. Bowen-Conradi syndrome

c. C syndrome

d. Congenital myotonic dystrophy e. Congenital myasthenia gravis

f. Faciocardiomelic syndrome g. Fetal alcohol syndrome h. FG syndrome

i. Marden-Walker syndrome j. Meckel syndrome k. Meningomyelocele

l. Mietens-Weber syndrome m. Miller-Dieker syndrome

n. Neu-Laxova syndrome o. Neurofibromatosis

p. Popliteal pterygium with facial clefts q. Potter syndrome

r. Pseudotrisomy 18 s. Spinal muscular atrophy

t. Syndrome of cloudy cornea, diaphragmatic defects, and distal limb deformities

u. Syndrome of craniofacial and brain anomalies and intrauterine growth retardation

v. Syndrome of cryptorchidism, chest deformity, and contractures

w. Toriello-Bauserman syndrome x. Walker-Warburg syndrome y. X-linked lethal arthrogryposis z. Zellweger syndrome

13. Prognosis

a. Poor prognosis for ventilator dependent neonates b. Prenatal factors that potentially predict respiratory

insufficiency

i. Decreased fetal movements ii. Polyhydramnios

iii. Micrognathia iv. Thin ribs

v. Decreased fetal movement often resulting in delayed developmental milestones

c. Skeletal changes secondary to the original deformities i. Scoliosis

ii. Deformed carpal and tarsal bones

iii. Under growing of limbs after longstanding contractures

iv. External genitalia often abnormal (e.g., cryptorchidism and absent labia majora) because of abnormal hip position

d. Intrinsically or extrinsically derived defects

i. Extrinsically derived contractures: an excellent prognosis

ii. Intrinsically derived contractures: a prognosis dependent on etiology

e. Prognosis depending on the condition’s natural history i. Developmental landmarks (attainment of motor,

social, and language milestones) ii. Growth of affected limbs iii. Progression of contractures

iv. CNS damage (lethal, stable, improving) v. Asymmetry of contractures (improving, worsen-

ing)

vi. Changes in trunk or limbs vii. Intellectual ability viii. Socialization

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f. Prognosis depending on the patient’s response to therapy

i. Spontaneous improvement ii. Response to physical therapy iii. Response to casting

iv. Types of surgery at appropriate time

v. Development of motor strength proportionate to limb size

DIAGNOSTIC INVESTIGATIONS

1. Lab studies

a. Laboratory tests, in general, are not useful

b. Creatine phosphokinase (CPK) levels when the following conditions are present:

i. Generalized weakness

ii. Doughy or decreased muscle mass iii. Progressive worsening

c. Viral cultures for an infectious process (intrauterine growth retardation, eye involvement, and hepato- splenomegaly)

d. Immunoglobulin M levels and specific viral titers (e.g., coxsackievirus, enterovirus, and Akabane virus) in the newborn for intrauterine infection

e. Maternal antibodies to neurotransmitters in the infant indicating myasthenia gravis

f. Cytogenetic study indicated in the following situations:

i. Multiple organ or system involvement

ii. Presence of CNS abnormalities, such as microcephaly, mental retardation, lethargy, degenera- tive changes, or eye anomalies

iii. Fibroblast chromosome study if lymphocyte chromosomes are normal and the patient has mental retardation without diagnosis

g. Nuclear DNA mutation analysis to identify certain disorders, such as spinal muscular dystrophy

h. Mitochondrial mutation analysis to identify certain disorders, such as mitochondrial myopathy

2. Imaging studies

a. Patient’s photographs

i. To document the extent of deformities (range of motion and position of arthrogryposis)

ii. To assess progress during treatment

b. Radiographs to evaluate the following skeletal and joint abnormalities:

i. Bony abnormalities (e.g., gracile bones, fusions,and extra or missing carpals and tarsals) ii. Disproportionately short stature (i.e., skeletal

dysplasias) iii. Scoliosis

iv. Ankylosis

v. Absence of patella vi. Humeroradial synostosis c. Ultrasonography

i. To evaluate the CNS and other viscera for anomalies

ii. To establish potential muscle tissue

d. CT scan to evaluate the CNS and the muscle mass e. MRI to evaluate muscle mass obscured by contractures

f. Ophthalmological evaluation for opacity and retinal degeneration

3. Histologic studies a. Neurogenic types

i. Muscle fiber type predominance or dispropor- tion is the most common neurogenic abnormality in arthrogryposis (26%). These are nonspecific alterations

ii. Dysgenesis of the motor nuclei of the spinal cord and brainstem causes the replacement of fasci- culi of muscle fibers by small muscle fibers and adipose tissue. Examples include Pierre-Robin syndrome and Möbius syndrome

iii. Dysgenesis of the CNS: the second most common neurogenic abnormality in arthrogryposis (23%), with disorganization and decrease in neu- rons of the cortex and motor nuclei of the brainstem and spinal cord. Clinical syndromes with this abnormality include trisomy 18, partial dele- tion of the long arm of chromosome 18 syndrome, and Zellweger syndrome

iv. Dysgenesis of the anterior horn, another common neurogenic abnormality in arthrogryposis v. Spinal muscular atrophy (e.g., Werdnig-

Hoffmann disease): another neurogenic abnormality in arthrogryposis

b. Myopathic types

i. Central core disease: a form of arthrogryposis in which the central portion of each muscle fiber contains a zone in which oxidative enzyme activity is absent

ii. Nemaline myopathy indicated by abnormal threadlike structures in muscle cells. In type I nemaline myopathy, nemaline rods are present.

In type II, the number of fibers with central nuclei is increased

iii. Congenital muscular dystrophy indicated by muscle fibers that demonstrate a rounded config- uration and conspicuous variation in diameter.

Perimysial and endomysial connective tissues are increased markedly

iv. Mitochondrial cytopathy indicated by numerous ragged-red fibers on muscle biopsy. It is associated with CNS abnormalities consistent with mitochondrial disease

v. Myoneural junction abnormality (e.g., congenital myasthenia gravis): another myopathic type of arthrogryposis

4. Procedures

a. Skin biopsy for culture of fibroblasts to be used for chromosome analysis and metabolic studies

b. Muscle biopsy

i. Probably the most important diagnostic proce- dure. It should be included in all autopsies and at time of surgery

ii. Distinguish myopathic from neuropathic conditions by obtaining muscle specimens from normal and affected areas

iii. Special histopathologic and electron micro- graphic studies to evaluate fatty and connective tissue replacement of muscle fibers and varia- tions in fiber size, such as decreased fiber diameter. All are nonspecific signs of muscle atrophy

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c. Electromyography (EMG) in normal and affected areas useful in differentiating neurogenic and myopathic causes

d. Nerve conduction tests to measure conduction veloc- ities in motor and sensory nerves. These should be performed when a peripheral neuropathy is suspected e. An autopsy to investigate the following:

i. CNS (i.e., brain neuropathology)

ii. Spinal cord (number and size of anterior horn cells, presence or absence of tracts at various levels)

iii. Ganglia and peripheral nerves iv. Eye (i.e., neuropathology)

v. Muscle tissue from different muscle groups (i.e., electron microscopy and special stains)

vi. Fibrous bands replacing muscle vii. Tendon attachments

viii. Other visceral anomalies, malformations, defor- mations, and disruptions

GENETIC COUNSELING

1. Recurrence risk: Recurrence risk depends on whether the contractures are extrinsically or intrinsically derived.

Extrinsically derived contractures have a low recurrence risk, while the recurrence risk for intrinsically derived contractures depends on etiology. Arthrogryposis may be inherited in the following ways with different recurrence risks:

a. Patient’s sib

i. Autosomal recessive: 25%

ii. Autosomal dominant: not increased unless a parent is affected or having gonadal mosaicism iii. X-linked recessive: 50% of male sibs affected if

the mother is a carrier b. Patient’s offspring

i. Autosomal recessive: not increased unless the spouse is also a carrier

ii. Autosomal dominant: 50%

iii. X-linked recessive: All daughters of affected males will be carriers. All sons of an affected male will be normal

c. Multifactorial: Combined effects of multiple genes and environmental factors cause multifactorial traits.

For most multifactorial diseases, empirical risks (risks based on direct observation of data) have been derived. For example, empirical recurrence risks of neural tube defects for siblings of an affected individual range from 2 to 5% in most populations

d. Mitochondrial: A small but significant number of diseases are caused by mitochondrial mutations.

Because of the unique properties of mitochondria, these diseases display characteristic modes of inheri- tance (i.e., inherited exclusively through the maternal line) with wide phenotypic variability. Only females can transmit the disease mutation to their offspring (e.g., distal type IIB arthrogryposis)

e. Sporadic: For those families in which a specific diagnosis cannot be made, the empiric recurrence risk to unaffected parents of an affected child, or to the affected individual with arthrogryposis, is about 3–5%

2. Prenatal diagnosis

a. Prenatal ultrasonography to detect the following:

i. Diminished fetal movement (main manifestation shared by various conditions with congenital contractures)

ii. Joint contractures (bilateral fixed flexion deformities of the hands, elbows, shoulders, hips, and knees, or talipes)

iii. Detection of subcutaneous edema (fetal hydrops) iv. Cystic hygroma

v. Increased nuchal translucency vi. Abnormal fetal lie

vii. Polyhydramnios or oligohydramnios

viii. Other associated anomalies (e.g., distended bladder in early urethral obstruction sequence; microcephaly, hydrocephaly, or hydranencephaly in

“cerebral dysgenesis” induced congenital contractures)

b. Chromosome analysis by amniocentesis or CVS for chromosome disorders

c. Molecular genetic analysis for certain genetic disorders with demonstrable mutations

3. Management

a. No completely successful approach to treatment b. Overall goals

i. Proper alignment of the lower limbs ii. Upper limb function for self-care

c. Early vigorous physical therapy to stretch contractures i. To improve joint motion

ii. To avoid muscle atrophy

iii. Excellent functional outcome in patients with amyoplasia or distal arthrogryposis

iv. May be harmful in diastrophic dysplasia because it may lead to joint ankylosis

v. Frequent recurrence of deformities following stretching, often requires surgery

d. Splinting combined with physical therapy i. Preferable to continuous casting

ii. Night splinting after surgical procedures indicated to maintain increased range of motion e. Feeding assistance and intubation needed in patients

with severe trismus f. Specific joint problems

i. Should be addressed with regard to treatment of other joints and the goals for the patient

ii. Early soft-tissue surgery with osteotomies when the growth is completed

iii. Tenotomies accompanied by capsulotomies in soft-tissue release procedures

iv. Long-term bracing and assistive devices usually needed

g. Feet

i. A rigid talipes equinovarus deformity: the most common deformity

ii. Goal of treatment: a plantigrade, braceable foot h. Knees

i. Goal of treatment: an extended knee for ambulation

ii. Flexion knee deformities more common than fixed knee deformities and more resistant to treatment

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i. Hips

i. Hip surgery follows foot and knee surgery, especially in the presence of knee extension deformities

ii. Hip surgery in patients younger than 1 year to facilitate ambulation. In some patients with bilateral hip dislocations and extremely mobile hips, open reduction may be attempted

j. Upper extremities

i. Treatment involves development of self-help skills (e.g., feeding and toileting) and mobility skills (e.g., pushing out of chair and using crutches)

ii. Consider overall function of the entire extremity rather than function of the individual joints in evaluating the upper extremities

iii. Consider upper extremity surgery until the patient is older than 5–6 years

k. Elbows

i. Goals: passive or active flexion capability (feeding arm) and extension capability (toilet arm) ii. Achieve elbow mobility before correcting a wrist

deformity because the elbow is crucial to hand function

l. Wrists

i. Stretching and splinting for the major wrist deformity (flexion with ulnar deviation)

ii. Proximal row carpectomy with or without fusion for a severe deformity

m. Fingers

i. Passive stretching and splinting for minimal to moderate flexion deformities

ii. Soft-tissue releases with proximal interphalangeal joint fusions for more severe deformities iii. Thumb-in-palm deformity to be corrected to pro-

vide opposition-improved grasp n. Spine

i. The spine affected in about one-third of patients ii. Scoliosis beginning early and progressing to become a long, severe, rigid, C-shaped curve.

This curve responds poorly to orthoses, as it is progressive

iii. Curves greater than 35°: treated with spinal fusion and instrumentation

o. Complications

i. Anesthesia: difficult to administer because vascular access often is restricted

ii. Intubation: posing problems for patients with a small underdeveloped jaw, limited movement of the temporomandibular joint, or a narrow airway iii. Osseous hypoplasia associated with decreased mechanical use in developing bone: prone to fracture at multiple sites. Multiple perinatal fractures have been observed in osteopenic bones p. Physical activity

i. Limited, because of existing orthopedic problems

ii. As a group, patients cope well socially and par- ticipate in social activities corresponding to their needs

iii. More restricted walking in patients with flexion contractures of the lower extremities than in those with extension contractures. Flexion contractures of the hips severely impair walking ability

iv. Contracture of the elbow causing a significant degree of disability in hand function

v. Impossible to use crutches in patients with upper extremity involvement associated with severe spinal deformity

vi. Dependent on help from other people to a higher degree in patients with more severe joint involvement than those with less severe joint involvement

vii. Independent living with productive lives for most children with normal intelligence despite severe handicaps. However, many remain par- tially dependent on others, such as parents, rela- tives, and government subsidy. Dependency is related more closely to personality, education, and overall coping skills than to the degree of physical deformity

viii. Good family support, a proper educational envi- ronment, and promotion of independence at an early age: required to achieve maximal function in addition to appropriate surgical correction

REFERENCES

Axt MW, Niethard FU, Doderlein L, et al.: Principles of treatment of the upper extremity in arthrogryposis multiplex congenita type I. J Pediatr Orthop [Br] 6:179–185, 1997.

Bamshed M, Jorde LB, Carey JC: A revised and extended classification of the distal arthrogryposes. Am J Med Genet 65:277–281, 1996.

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Fig. 2. Two infants with arthrogryposis multiplex congenita character- ized by flexion contractures of the knees and fingers, and equinovarus deformities of the feet.

Fig. 1. An infant with amyoplasia congenita showing typical, sym- metrical positioning of the limbs, internally rotated and adducted shoulders, fixed extended elbows, pronated forearms, flexed wrists and fingers, and severe talipes equinovarus deformity.

Fig. 3. An infant with distal arthrogryposis showing predominantly distal contractures with overlapping finger contractures, ulnar deviation of fingers, and clubfeet.