Why The Presentation Of Amniotic Band Syndrome Can Be Misleading

Amniotic band syndrome is a congenital condition in which early amniotic rupture leads to the formation of the mesodermal fibrous strands that entangle limbs and appendages. This occurs in utero with the congenital deformity reaching its final form before birth. It most commonly involves the distal aspect of extremities such as the fingers or toes. Researchers have noted the prevalence of the condition ranges from 1:1,2000 to 1:5,000 births.¹ Physicians have referred to amniotic band syndrome as the most common cause of terminal congenital malformations of a limb.²

Amniotic bands can construct, entangle or amputate fingers or toes that protrude the farthest such as the hallux in the foot. The bands can present with variable width and depth, ranging from shallow indentations of the skin to deep grooves extending down to deep fascia or bone. The malformations can present in a variety of ways and authors describe them as never appearing more than once with the same presentation.¹

In the photo at the left, note a traumatically detached great toenail from an otherwise healthy 3-year old. The great toenail, as well as the second toenail, on the left foot had been deformed since birth.

Upon clinical examination, it was apparent that the second digit itself was also deformed. The distal aspect of the toe had a much smaller circumference than the proximal portion of the toe with reference to the proximal interphalangeal joint. The nail was barely present and the proximal portion was significantly dystrophic. The parents confirmed the second toe had this appearance since birth, which prompted many questions at pediatrician visits without any definitive answers. 

More than likely, this is a case of amniotic band syndrome that has clearly affected the second toe but also has caused deformation of the nail plates. The history of these deformities being present since birth makes the likelihood of this being amniotic band syndrome even greater as it would explain the dystrophic appearance of the toenails as a result of the nail or matrix trauma from the bands. This particular case is an example of phalangeal hypoplasia in which the distal digit had been "lassoed," resulting in malformation.  With this patient, I avulsed the hallux nail to resolve the inflammation from the trauma to the nail.

Final Notes

As foot and ankle specialists, we should become familiar with amniotic band syndrome so if that condition presents, one can reassure the parents on what the condition is and why it has occurred. In the absence of trauma, one could very easily mislead the parents into a workup for onychomycosis and possibly even a treatment that would be unnecessary.

The diagnosis of amniotic band syndrome typically occurs with the use of three-dimensional ultrasonography. Physicians can diagnose this condition at as early as 12 weeks of gestation.³

The treatment of amniotic band syndrome depends on the type and severity of the deformity. If syndactyly is present, one can perform a desyndactylization procedure to reduced webbed toes. Surgeons can address a short digit or digits with a distraction osteotomy depending on the severity. In severe cases, amputation may be necessary. Researchers have also described preventative options such as in utero surgery.⁴ Authors have also noted that clubfoot can be associated with amniotic band syndrome and describe Ponseti casting as an effective treatment option.⁵ 

References

1. Walter JH Jr., Goss LR, Lazzara AT. Amniotic band syndrome. J Foot Ankle Surg. 1998;37(4):325-33. 
2. Goss L. Amniotic band syndrome. Podiatry Network. Available at https://www.podiatrynetwork.com/document_disorders.cfm?id=240 .
3. Turğal M, Ozyüncü O, Yazıcıoğlu A, Onderoğlu LS. Integration of three-dimensional ultrasonography in the prenatal diagnosis of amniotic band syndrome: A case report. J Turk Ger Gynecol Assoc. 2014;15(1):56-9.
4. Sala P, Prefumo F, Pastorino D, Buffi D, Gaggero CR, Foppiano M, De Biasio P. Fetal surgery: an overview. Obstet Gynecol Surv. 2014;69(4):218-28.
5. Carpiaux AM, Hosseinzadeh P, Muchow RD, Iwinski HJ, Walker JL, Milbrandt TA.  The effectiveness of the Ponseti method for treating clubfoot associated with amniotic band syndrome. J Pediatr Orthop. 2015; epub May 6