= ARTHROGRYPOSIS MULTIPLEX CONGENITA

= nonprogressive congenital syndromic complex characterized by poorly developed + contracted muscles, deformed joints with thickened periarticular capsule and intact sensory system

Pathophysiology:

• congenital / acquired defect of motor unit (anterior horn cells, nerve roots, peripheral nerves, motor end plates, muscle) early in fetal life with immobilization of joints at various stages in their development

Cause: ? neurotropic agents, toxic chemicals, hard drugs, hyperthermia, neuromuscular blocking agents, mytotic abnormalities, mechanical immobilization

Frequency: 0.03% of newborn infants; 5% risk of recurrence in sibling

Path: diminution in size of muscle fibers + fat deposits in fibrous tissue

Associated with:

1. neurogenic disorders (90%)
2. myopathic disorders
3. skeletal dysplasias
4. intrauterine limitation of movement (myomata, amniotic band, twin, oligohydramnios)
5. connective tissue disorders

Distribution: all extremities (46%), lower extremities only (43%), upper extremities only (11%); peripheral joints >>proximal joints; symmetrical

• clubfoot; claw hand ; congenital dislocation of hip
• diminished muscle mass; skin webs

• flexion + extension contractures
• osteopenia ± pathologic fractures
• congenital dislocation of hip
• carpal coalition
• vertical talus
• calcaneal valgus deformity