Congenital Amniotic Band Syndrome (ABS)

Congenital Amniotic Band Syndrome (ABS), or Streeter dysplasia, is a complex congenital disorder characterized by constricting amniotic bands formed in utero. While the etiology remains a topic of debate, the common final pathway results in encircling strands of fibrous tissue causing extrinsic compression of developing fetus, resulting in deformity, vascular occlusion, and possible amputation. Although variable in presentation, appendages are more often involved, and common orthopaedic manifestations include the characteristic extremity bands, club foot, anterolateral bowing of the tibia, tibial pseudarthrosis, leg-length discrepancy, and hemihypertrophy. Other associated clinical findings include craniofacial abnormalities, cardiac defects, renal abnormalities, and neural tube defects. ABS is a clinical diagnosis, though ultrasonography may aid in characterizing the associated defects in utero. Treatment involves surgical release of the constricting bands, sometimes urgently in the presence of neurovascular compromise. Long-term monitoring is necessary until skeletal maturity to assess for the development of contractures and growth disturbance.