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Current Insights On The Surgical Treatment Of Pediatric Polydactyly
Addressing questions of foot function and cosmesis, these authors describe operative techniques for removing a sixth toe in a 14-month-old girl.
What happens to the sixth little piggy?
Polydactyly, the most common congenital hand anomaly, is a condition in which a person has more than five fingers on one hand or more than five toes on one foot.1 Polydactyly is ubiquitous in nature and reportedly occurs in other species, including cats, horses, pigs and chickens.2 Polydactyly of the fifth toe is the most common congenital malformation of the forefoot and Watanabe and colleagues have classified polydactyly of the fifth toe as fifth ray duplication.3
Some things to consider when identifying this condition are that it can occur on its own and other diseases or symptoms do not necessarily need to be present. Researchers have also linked polydactyly to a trait involving only one gene that has multiple variations within itself.4 Families may pass down the trait as an isolated, benign condition, like having a hitchhiker's thumb or being double jointed, which is considered non-syndromic. When looking at certain ethnic groups, there are some types of polydactyly that show up more often than others. African-Americans can inherit this supernumerary digit without genetic disease and it most commonly presents as postaxial polydactyly.5
Polydactyly can also occur with some genetic diseases and often the trait may exist as part of a syndrome. Some syndromes that might present with polydactyly include Greig cephalopolysyndactyly syndrome or Bardet-Biedl syndrome.
We can broadly classify polydactyly as pre-axial (which adds an extra digit medially), post-axial (extra digit laterally) and central (which involves one of the middle three digits).
A Closer Look At The Epidemiology
The estimated incidence is different for pre- and post-axial polydactyly.6 For post-axial polydactyly, the incidence is an estimated 1 in 3,000 people while pre-axial polydactyly happens less frequently, occurring about 1 in 7,000 people. Central polydactyly is the most rare of these conditions.
There are different presentations of this extra digit including those involving skin and soft tissue, and others that include bone that may or may not have joint involvement. Wassel proposed the most widely used and accepted classification system of pre-axial polydactyly in 1969 (see chart at right).7 Authors classified the seven groups based on the level of the bifurcation. Starting from distal to proximal, types I, III and V refer to bifid phalanges, and types II, IV and VI refer to complete phalangeal duplications.
A 14-month-old Caucasian female presented to the office with a sixth toe on her right foot. The mother stated that many males in her family have this lucky digit but she would rather have it removed for her daughter. The mother stated that her daughter has started to walk recently but has not noticed the extra toe altering the way she walks. The toddler was healthy and did not take any medications. Her history was unremarkable for genetic diseases and syndromes.
The image at left shows a preoperative view of the right foot. In this photo, you can see the sixth toe deviated from the rest of the foot and that it was not part of the normal metatarsal parabola. An AP radiograph of the right foot shows a bifid metatarsal with both being underdeveloped and a delay in the ossification centers (type V in the Wassel classification)
After identifying this, I scheduled the surgery and discussed consent with the mother. The surgical plan involved the resection of the supernumerary digit as well as the lateral bifid head of the fifth metatarsal. This would ensure adequate skin for closure and a normal contour to the lateral aspect of the foot.
The photo at left shows the right foot seven days post-op. The normal parabola of the foot is apparent during physical examination. The last image, an AP radiograph of the right foot seven days post-op, shows the successful resection of the metatarsal head.
In Conclusion
There are controversies among surgeons as to which toe to excise in postaxial polydactyly. Nakamura and coworkers asserted that lateral toe excision was advantageous in terms of obtaining a natural form of the reconstructed toe and reported no complications of poor blood circulation or eventual corn formation.8 There are also controversies among surgeons regarding the treatment of polydactyly with various flap techniques.
This surgery for postaxial polydactyly was for functionality as well as cosmetic surgery. The most important concept in polydactyly cases is the importance of a comprehensive physical and radiological examination in pre-operative planning. Cosmesis is certainly a component of surgical correction but functionality for shoe fit becomes the driving factor for surgical intervention.
Dr. DeHeer is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Podiatric Surgery. He is also a team podiatrist for the Indiana Pacers and the Indiana Fever. Dr. DeHeer is in private practice with various offices in Indianapolis and is the founder of Step by Step Haiti.
Dr. Leshikar is a second year resident at St. Vincent Hospital in Indianapolis.
References
1. Bunnell S. Surgery of the Hand, Fourth Edition. Lippincott, Philadelphia, 1964.
2. Gorbach D, Mote B, Totir L, et al. Polydactyl inheritance in the pig. J Hered. 2010;101(4):469-75.
3. Watanabe H, Fujita S, Oka I. Polydactyly of the foot: an analysis of 265 cases and a morphological classification. Plast Reconstr Surg. 1992;89(5):856-877.
4. Hosalkar HS, Spiegel DA, Davidson RS. Toe deformities. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF (eds.). Nelson Textbook of Pediatrics, 19th Edition. Saunders Elsevier, Philadelphia, 2011, pp. 666.
5. Yochum TR, Rowe LJ. Essentials of Skeletal Radiology. Lippincott Williams and Wilkins, Philadelphia, 2004.
6. Entezami M, Albig M, Knoll U, et al. Ultrasound Diagnosis of Fetal Anomalies. Thieme Medical, New York, 2003.
7. Wassel HD. The results of surgery for polydactyly of the thumb. A review. Clin Orthop Relat Res. 1969;64:175-93.
8. Nakamura J, Kubo E, Maesawa N. Our repair procedure for polydactyly of the fifth toe ray. Jpn J Plast Reconstr Surg. 1991;34:1071.
9. Bromley B, Benacerraf B. Abnormalities of the hands and feet in the fetus: sonographic findings. AJR Am J Roentgenol. 1995;165(5):1239-43.
10. Tore HG, Mckinney AM, Nagar VA et al. Syndrome of megalencephaly, polydactyly, and polymicrogyria lacking frank hydrocephalus, with associated MR imaging findings. AJNR Am J Neuroradiol. 2009;30(8):1620-2.
11. Bowerman RA. Anomalies of the fetal skeleton: sonographic findings. AJR Am J Roentgenol. 1995;164(4):973-9.
12. Poretti A, Brehmer U, Scheer I et al. Prenatal and neonatal MR imaging findings in oral-facial-digital syndrome type VI. AJNR Am J Neuroradiol. 2008;29(6):1090-1.
13. Son SH, Kim YJ, Kim ES et al. A case of McKusick-Kaufman syndrome. Korean J Pediatr. 2011;54(5):219-23.
