Arthrogryposis multiplex congenita due to physical constraint occurs when the capacity of the uterine cavity is small and asymmetric or when the fetus is affected by cutaneous bands that restrict limb movements. The capacity of the uterus may be restricted by oligohydramnios, anatomic malformations, amniotic bands, or uterine tumors. Thick cutaneous bands that restrict fetal joint movements occur in Escobar syndrome.

Oligohydramnios sequence
Oligohydramnios is the most frequent cause of arthrogryposis multiplex due to physical constraint. A reduced uterine capacity may produces arthogryposis (click in figure) but in addition places the fetus at risk for multiple anomalies.

The constellation of findings that occur as the result of decreased amniotic fluid is called oligohydramnios sequence. The characteristic features of oligohydramnios sequence are wrinkled skin; skin folds that extend from the inner canthus to the upper cheek; squashed nose; large, low-set and posteriorly rotated ears; short neck; and large wrinkled hands. Neonates may also show scars at skin areas of maximal pressure (Figure 156.1 A). Arthrogryposis usually involves the knees, feet, wrist and elbow (Figure 156.1 B). The most frequent causes of oligohydramnios are placental insufficiency and premature rupture of membranes. Bilateral renal agenesis is a rare but severe cause of oligohydramnios often associated with arthrogryposis.

A	B

Figure 156.1.— Arthrogryposis due to physical constrain. [A] scar; [B] arthrogryposis of the wrist.

Escobar syndrome
Escobar syndrome or multiple pterygia syndrome is characterized by thick skin folds that produce an unusual appearance and keep the joints in a fixed position. The skin folds are usually in the neck, axilla, antecubital, popliteal, and digital areas. The thick skin folds reduce joint motility in utero and lead to arthrogryposis multiplex congenita. Arthrogryposis is especially marked in the hands. Intelligence is normal. Scoliosis often develops by five years of age. Escobar syndrome is an autosomal recessive condition. Surgical treatment of the pterygium may be necessary.

Neurological disorders should be suspected in any neonate without signs that suggest a cartilaginous abnormality, oligohydramnios sequence, or Escobar syndrome. Neurological abnormalities can be classified based on the region of the nervous system most affected.