CHAPTER 67
Arthrogryposis
Introduction/Etiology/Epidemiology
• The term arthrogryposis is derived from the Greek, meaning “curved joint.”
• It refers to a group of more than 400 syndromes in which multiple joint contractures are present at birth.
— The most recognizable of these syndromes is amyoplasia.
— All are associated with decreased fetal movement, which results in multiple joint contractures, which can be diagnosed on prenatal ultrasonography.
— There are numerous primary etiologies.
• The incidence of arthrogryposis is 1 in 3,000 live births.
• The incidence of amyoplasia (most common form) is 1 in 10,000 live births.
• About half of the conditions associated with arthrogryposis have a syndromic or genetic abnormality.
— Determining the cause of each patient’s arthrogryposis is important to predict risk of additional children born to the same parents being affected.
— It is also important to determine if unaffected siblings are carriers of the condition.
— Amyoplasia is thought to be nongenetic.
• When arthrogryposis is seen along with an intellectual disability, a genetic evaluation should be performed.
— Microarray
— Exome studies
• Clinical classification is based on the system or systems involved.
— Primary limb involvement (eg, amyoplasia, distal arthrogryposis)
— Musculoskeletal plus other system involvement
— Musculoskeletal plus other system dysfunction, intellectual disability, or lethality
• The overall cause of fetal akinesia may be
— Intrinsic conditions (eg, neuromuscular disease)
— Environmental conditions (ie, maternal illness or exposures)
— Extrinsic conditions (eg, lack of intrauterine space)
• The etiologic process may be neuropathic (myelin defects, myopathies), metabolic disorders, skeletal dysplasias, space limitations, maternal conditions, or intrauterine vascular compromise
• Presentations
— Amyoplasia
— Distal arthrogryposis
— Everything else (pterygium syndromes, X-linked syndromes, teratologic conditions, maternal illness, intellectual disability, fetal akinesia deformation sequence, lethal conditions)
Signs and Symptoms
• Pregnancy history typically reveals decreased fetal movements.
• Loss of skin creases across joints
• Dimples may be present over the extensor surfaces of involved joints.
• Severe muscle atrophy and a decrease in subcutaneous fat
• Joint motion is restricted, and there is a firm inelastic block with passive motion.
• The shoulders are internally rotated and adducted.
• The elbows are extended with the forearms pronated.
• The wrist and fingers are flexed.
• The fingers are thin and tapered.
• Foot deformities are present in 90% of patients.
— Clubfoot is the most common, especially in amyoplasia
— Vertical talus is also seen.
• Seventy percent have knee contractures, both flexion and extension.
• Forty percent have hip deformities including subluxation, frank dislocation, and contracture.
• The occurrence of scoliosis in patients with amyoplasia is common.
Differential Diagnosis
• Bilateral brachial plexus palsy
• Bony fusion
— Symphalangism (ie, fusion of phalanges)
— Coalition (ie, fusion of the carpals and tarsal bones)
— Synostosis (ie, fusion of long bones)
• Absence of dermal ridges
• Absence of distal interphalangeal joint creases
• Amniotic bands
• Antecubital webbing
• Camptodactyly
• Coalition
• Humeroradial synostosis
• Familial impaired pronation and supination of forearm
• Liebenberg syndrome
• Nail-patella syndrome
• Nievergelt-Pearlman syndrome
• Poland anomaly
• Tel Hashomer camptodactyly
• Trismus-pseudocamptodactyly syndrome
Diagnostic Considerations
• Diagnosis is established based on history and physical examination and consultation with specialists in genetics and/or neurology as indicated.
• Electromyograms and muscle biopsies are of little value, although these tests may help to differentiate between myopathic and neuropathic forms.
• Prenatal ultrasonography may suggest the diagnosis when it shows decreased or absent fetal movement in association with oligohydramnios and joint contractures.
Treatment
• Management requires a multidisciplinary team including a pediatric neurologist, pediatric orthopaedic surgeon, rehabilitation physician, geneticist, occupational therapist, physical therapist, and orthotist.
• The goal of treatment is to optimize function and independence.
• In the lower extremities, the goal is alignment and stability for ambulation.
• In the newborn, a program of early physical therapy and/or occupational therapy, as well as stretching and bracing, can be successful in improving passive range of motion.
— Careful attention to the birth process is important to make sure there are no long bone fractures before beginning a stretching program.
— Serial stretching casts, applied on a weekly basis, are initiated soon after birth.
— A percutaneous Achilles tenotomy can also be done, as in the Ponseti technique.
• Foot deformities are very difficult to correct and may require surgery (extensive posteromedial release) in addition to the Ponseti method of casting.
— The surgical correction is done at about 1 year of age.
— Because the recurrence rate is high, long-term bracing is required postoperatively.
— Talectomy is reserved for severe recurrent deformities.
• Knee contractures
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