summary Constriction Ring Syndrome, also known as Streeter's Dysplasia or Amniotic band syndrome, is a congenital condition that occurs when loose fibrous bands of ruptured amnion adhere to and entangle the normal developing structures of the fetus. Diagnosis is made clinically at birth with the presence of bands perpendicular to the longitudinal axis of the digit or limb with normal anatomy proximal to the constriction ring. Treatment is usually the release of the bands or digital reconstruction depending on the severity of digital compromise. Epidemiology Incidence 1:15,000 live births Demographics affects males and females equally Anatomic location occurs in hands and fingers 80% of the time greater than 90% occur distal to wrist Etiology Pathophysiology no firmly established etiology most accepted theory is that the disrupted amnion releases fibrous membranous strands which wrap around the developing limb in a circumferential fashion Genetics inheritance pattern sporadic and not hereditary Associated conditions orthopaedic clubfoot syndactyly nonorthopaedic cleft palate cleft lip craniofacial defects cardiac defect Encephalocele Classification Patterson Classification Type I Simple constriction ring Type II Deformity distal to ring (hypoplasia, lymphedema)Edema may or may not be present Type III Fusions distally (syndactyly, acrosyndactyly) Type IV Amputation Degrees of Constrictive Ring Syndrome Simple constriction rings Mild ring with no distal deformity or lymphedema Rings with distal deformity Ring may cause distal lymphedema in association with deformity Acrosyndactyly Fusion between the more distal portions of the digits with the space between the digits varying from broad to pinpoint in size. Amputations Loss of limb distal to ring Presentation Symptoms most patient asymptomatic and diagnosed at birth Physical exam normal anatomy proximal to constriction ring bands perpendicular to longitudinal axis of the digit or limb most common presentation central digits more commonly affected amputations distal to constriction site can be found when no amputations present look for secondary syndactyly bony fusions may observe sinus tracts proximally between digits Imaging Ultrasound intrauterine diagnosis can be made with ultrasound at end of first trimester Treatment Nonoperative observation indications Type I (simple constriction ring) Operative excision or release of constriction band indications Type I with compromise of digital circulation circumferential Z-plasties indications Type II distal deformities present surgical release of syndactyly indications Type III with distal fusions reconstruction of involved digits or limb (i.e., lengthening of bone, deepening of web space) indications Type IV to improve function Complications Extremity amputation Prognosis Related to location and severity of constricting bands