Malformation associated with constriction ring syndromeThe percentage of associated anomalies varies from 40% to as high as 80%
Constriction ring deformities are as common on the lower extremity as on the upper, almost all of these involve the musculoskeletal system, with clubbed feet being the most common in up to 30% of reported cases. Large reported series reveal an incidence between 5% and 15% of craniofacial malformations with clefting of the lip or palate. Prevention
Amniotic band syndrome is considered an accidental event and it does not appear to be genetic or hereditary, so the likelihood of it occurring in another pregnancy is remote. The cause of amnion tearing is unknown and as such there are no known preventative measures. Treatment
Surgical correction is recommended when a constriction ring results in a limb contour deformity, with or without lymphedema. Surgical technique
At the beginning of the surgery a tourniquet will be applied to the limb. A tourniquet compresses and controls local arterial and venous circulation for about 2 hours. The constriction band must be dissected very carefully to avoid damaging the underlying neurovasculature. When the constriction band is excised, there will be a direct closure. This allows the fatty tissue to naturally reposition itself under the skin. "With complete circumferential constriction bands, it is recommended that a two-stage correction approach be used. At the first operation, one-half of the circumference is excised and the other one-half can be excised after three to six months.
Expanding over subdivision in depth of the clefts for every classification is not necessary because the principles of treatment and technique for correction are the same.There are four categories:

simple constriction rings
constriction rings associated with deformity of the distal part with or without lymphedema
constriction rings associated with acrosyndactyly
uterine amputationPatterson divided the constriction ring associated with acrosyndactyly into three types:

Type I: conjoined fingertips with well-formed webs of the proper depth
Type II: the tips of the digits are joined, but web formation is not complete
Type III: joined tips, sinus tracts between digits and absent websPatterson IThere are simple constriction rings which are strands most commonly around the distal extremities as fingers and toes. In general, the thumb is not likely to be affected by a constriction ring because the fetus typically holds the thumb in tight adduction flexion, making entanglement with strands less likely. These malformations need to be surgically removed which must be executed in different stages and can done by different techniques (see also treatment). Patterson IIThe CRS involves strands which obstruct the lymphatic vessels and thus causing fluid retention, distal of the affected extremity. This utters itself with swollen parts distal of the constriction. Patterson IIIIn this form there is a complex form of syndactyly named acrosyndactyly, the fingers (or toes) were initially separated but due to the constriction they are formed back together. Sometimes multiple fingers can be involved. The distal fusion between digits or toes never initially involves a skeletal coalition. The digits are usually hypoplastic if multiple digits are involved.