Amniotic band syndrome (ABS) is a congenital disorder characterized by limb constrictions. The disorder lacks precise definition, and its exact pathogenesis is unknown. Though theories have been advanced to explain the condition’s origin, none have been scientifically validated. The “exogenous” theory, popularized by Torpin, is the most widely accepted. It suggests that early amniotic rupture leads to formation of amniotic strands, which by means of progressive compression induce formation of extremity bands. In this disorder, histological examination of the excised bands demonstrates them to be composed of fibrous tissue. Multiple clinical and experimental data reveal this theory has only low plausibility. Our purpose is to assess whether annular external compression of a fetal rabbit limb will produce a band of subcutaneous fibrous tissue characteristic of amniotic band syndrome.

We operated on one limb of 10 different rabbit fetuses, each at 21 days of gestation. The extremity was ligated with a nylon suture at the infracondylar level. At 30 days gestation, each fetus was delivered by caesarean section. Limbs were analyzed histologically using different techniques. Histological analysis did not show subcutaneous fibrous tissue in the mechanically constricted zone. The distal segment showed dilatation of lymphatic vessels and edema of soft tissue.

Annular external compression of a fetal rabbit limb does not induce development of new fibrous tissue; therefore this experimental study does not support the theory of a mechanical exogenous pathogenesis in amniotic band syndrome.

Introduction. With the use of fetoscopy (minimally invasive surgery), the indications for foetal surgery have been expanded. Extremities at risk of amputation by EAB are amenable to foetal surgery. A previous model of in uterus reparation of moderate EAB has been reported. The purpose of this study is to evaluate the feasibility of intrauterine foetal release of amputating EAB.

Material and methods. Right limbs of fifteen 60-days gestational age pregnant sheep were ligated with silk suture at the infracondilar level. Left limbs were used for paired comparison. Foetuses were randomized in three groups: early repair group (n=5), late repair group (n=5) and no-repair group (n=5). The limbs of repaired groups underwent foetal release. The limbs obtained from at term foetuses were analyzed morphologically, functionally, radiologically, and histologically. Statistical analysis with paired test was used to compare data.

Results. Non-repaired limbs showed amputation or quasi-amputation; the repaired ones did not. However, those late repaired had significantly reduced passive ankle range of motion, shorter limb length, and mild residual changes.

Conclusions. In uterus release of potentially severe EAB avoids limb amputation and permits its morphological and functional recovery. Early release shows better results.