Arthrogryposis Multiplex Congenita

Arthrogryposis multiplex congenita is a congenital deformity affecting the extremities, characterized by marked muscular wasting the loss of mass, increased fibrous tissue around the joints, and therefore disturbance of mobility and various characteristic deformities.

Bone changes are usually secondary to the overlying soft tissue changes, as well as to the changes which have taken place within the joint.

In its usual form, there is unilateral or bilateral club foot and club hand, and these constitute the most obvious of the deformities with the rigidity of the parts, it beings impossible often to obtain any degree of movement at the affected joints.

When the condition affects the lower limbs, there are also present contractures of the knee and the hip which are often the site of a congenital dislocation

Current use of the term signifies heterogeneous group of disorders that all include the common feature of multiple congenital joint contractures.

It must be noted that arthrogryposis as a physical sign is present in many other conditions as well.

Amyoplasia is most common type of arthrogryposis.

Associated Deformities and Malformations

• Limb deformities – pterygium, shortening, webs, compression, absent patella, dislocated radial heads.
• Face – Facial asymmetry, flat nasal bridge, hemangioma, micrognathia, hypertelorism, cleft palate and trismus.

• Scoliosis
• Genital deformities – cryptorchidism, lack of labia, microphallus
• Small and malformed eyes, corneal opacities, ptosis, strabismus
• Tracheal and laryngeal clefts and stenosis. Hypoplasia of lungs, hypoplastic diaphragm
• Skin hemangiomas
• Congenital cardiac anomalies and cardiomyopathy.
• Structural abnormalities of kidneys, ureters, and bladder
• Decreased muscle mass, soft muscle texture, fibrous bands, abnormal tendon attachments.

Pathophysiology of Arthrogryposis

Decreased fetal movements or fetal akinesis has been suggested to be the major contributory cause. The decrease in activity could be due to fetal abnormalities or maternal disorders like.

Motion is essential for the normal development of joints and their contiguous structures; lack of fetal movement causes extra connective tissue to develop around the joint resulting in fixation of the joint.

The frequency is about 1 in 3,000 live births.

Males are primarily affected in X-linked recessive disorders. Otherwise,  males and females are equally affected.

Risk Factors for Arthrogryposis

• Family history
• consanguineous marriages.
• Increased maternal age or multiple previous miscarriages
• Risk is increased in infants born to mothers affected with
  • Myotonic dystrophy
  • Myasthenia gravis
  • Multiple sclerosis
• Maternal infections
  • Rubella
  • Rubeola
  • Coxsackievirus enterovirus

• History of Maternal fever of more than 39°C for an extended period
• Drug exposure like drugs, alcohol, curare, methocarbamol, and phenytoin, may lead to decreased fetal movement.
• Decreased amniotic fluid [Oligohydramnios]
• Uterine abnormalities
• Trauma to abdomen during pregnancy
• Breech or transverse fetal position
• Abnormal placenta
• Multiple Births

Presentation

Arthrogryposis is detectable at birth or in utero using ultrasonography Involved extremities are fusiform or cylindrical in shape, with thin subcutaneous tissue and absent skin creases.

Deformities are usually symmetric, and severity increases distally. Thus in a given limb, the hands and feet the most deformed. Joints are rigid and joints like hips and knee may be dislocated.

Limb atrophy is seen and muscles or muscle groups may be absent.

Sensation is usually intact, although deep tendon reflexes may be diminished or absent.

Joint contractures are present. Distal joints are affected more frequently than proximal joints.

Range of motion in the jaw is frequently limited.

Contractures could be intrinsic which are frequently associated with polyhydramnios, symmetric and accompanied by taut skin, pterygia across joints, and absent flexion creases.

Extrinsic contractures are associated with positional limb anomalies, loose skin, and normal or exaggerated flexion creases. Patients have an excellent prognosis.

Deformities and malformations as noted before can be associated.

Differential Diagnoses

• Faciocardiomelic syndrome
• Maternal multiple sclerosis
• Maternal autoantibodies
• Marden-Walker syndrome
• Meckel syndrome
• Meningomyelocele
• Mietens syndrome
• Miller-Dieker syndrome
• Neurofibromatosis
• Congenital myotonic dystrophy
• Congenital myasthenia gravis
• Popliteal pterygium with facial clefts
• Pseudotrisomy 18
• Spinal muscular atrophy
• Sturge-Weber syndrome
• Toriello-Bauserman syndrome
• Zellweger syndrome

Lab Studies

Lab tests are not useful in diagnosing arthrogryposis.

• Creatine phosphokinase levels may be done to rule out myopathy
• Viral cultures may reveal an infectious process.
• Immunoglobulin M levels and specific viral titers like coxsackievirus, enterovirus and  Akabane virus in the newborn may reveal intrauterine infection.
• Maternal antibodies to neurotransmitters in the infant may indicate myasthenia gravis.
• Nuclear DNA mutation analysis is used to identify certain disorders, such as spinal muscular dystrophy.
• Mitochondrial mutation analysis is used to identify mitochondrial myopathy.

• Skin biopsy for culture of fibroblasts is used for chromosome analysis.
• Muscle biopsy distinguishes myopathic from neuropathic conditions

Imaging

X-rays are done to evaluate skeletal and joint abnormalities:

Ultrasonography evaluates the CNS anomalies, visceral anomalies and establishes potential muscle tissue. CT and MRI do a better job though.

However, ultrasound is good in identification of multiple contractures with ultrasound.

Ophthalmologic evaluation is done for opacity and retinal degeneration.

Treatment

Arthrogryposis cannot be cured.

The treatment goals are ambulation and  self-care. Lower limb alignment for ambulation and upper limb alignment for self care is done. Early gentle manipulation soon after birth improves passive and active range of motion Early vigorous physical therapy to stretch contractures is very important in improving joint motion and avoiding muscle atrophy.

Recurrence of deformities following stretching is common, and surgery is often indicated.

Feeding assistance and intubation is needed in patients with severe trismus.

Late manipulation is of little value.

Surgery

The perioperative management of these patients is difficult due to various issues.

For limbs, soft-tissue surgery should be performed early. Osteotomies should be done after growth is completed.

Lower Limb

Feet

The goal of treatment is a plantigrade foot.

The most common deformity is a rigid talipes equinovarus deformity.

The patient needs an extensive medial and lateral release and bony procedures at a later stage. In skeletally advanced patients, triple arthrodesis may be required.

Knees

The goal of treatment is an extended knee for ambulation. Release of contractures and osteotomies may be needed.

Hips

Hip surgery should be done after  foot and knee surgery. Unilateral hip dislocation requires reduction  but in bilateral affliction, the reduction is not done.

Upper Limb

Upper extremities deformities require passive stretching and splinting Soft-tissue releases may also be needed.

Spine

Scoliosis greater than 35° should be treated with spinal fusion and instrumentation.

Prognosis

Ventilator dependence in neonatal period is associated with a poor prognosis. Prognosis also depends on natural history and the patient’s response to therapy.

Most children with normal intelligence can have  independent, productive lives. However, many remain partially dependent on others.

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