When An Adult Presents With Postaxial Polydactyly Of The Foot

Presenting an unusual case of an adult with bilateral postaxial polydactyly, these authors outline the pertinent clinical science, case workup and treatment options.

Polydactyly describes a group of pathologies characterized by the presence of one or more additional digits than the standard five.^1-12 These supernumerary digits may present medially (pre-axial), laterally (post-axial) or centrally.⁴ Most cases are treated during childhood with adult cases being far less common.

We present the case of a 37-year-old male with post-axial polydactyly of the bilateral feet. The patient’s primary complaint was the inability to wear enclosed shoes without pain on the left foot. The patient did not experience any pain on the right foot and did not want any treatment for the right foot. He denied a family history of any similar condition. The patient had a history of Herpes zoster and was taking valacyclovir (GlaxoSmithKline) 500 mg for this infection. He had no history of allergies or hypersensitivity.

Upon physical examination, it was clear the patient had two fully developed fifth and sixth digits with separate nail plates. There was no webbing of the interdigital spaces (see first photo above), which clinicians see in approximately 10 percent of polydactyly cases.³ The patient had no neurovascular or additional musculoskeletal abnormalities.

Dorsoplantar and medial oblique radiographs were taken to classify the deformity as well as identify any other bony abnormality or joint involvement. Radiographic imaging revealed an extra fully developed sixth toe (see second image above), With confirmation of the soft tissue plane of the accessory bone on radiographs and no evidence of coalition or arthrosis, we decided that a computerized tomography (CT) scan was unnecessary.

After preoperative evaluation, we decided to remove the most lateral digit to leave the most natural-appearing and functional toe. Employing a semi-elliptical incision, we utilized a #15 blade to take the incision down to bone at the metatarsophalangeal joint, taking care to preserve all vital neurovascular structures. We amputated the sixth toe in total and sent it to pathology for evaluation. The report showed no malignancies or suspected pathology outside of an accessory digit.

Due to the patient’s age, growth arrest of the fifth toe and fifth metatarsal was not a concern. We closed the incision and the patient was discharged on the same day in a compressive dressing with a surgical shoe (see third and fourth images above). We removed sutures two weeks after the surgery. At three weeks post-op, the patient transitioned to regular shoes and at four weeks, the patient returned to normal daily activity, free of pain or complications related to surgery.

What You Need To Know About Polydactyly

Polydactyly may exist as a single structural abnormality that can be inherited or it may be associated with various morphologic phenotypes as part of a syndrome (syndromic polydactyly).¹ It is commonly associated with musculoskeletal syndromes.^2-4 Thirty percent of affected patients have an autosomal dominant family history inheritance pattern.^6,12  Duplication may occur only at the distal and intermediate phalanx, or may occur at the whole digit and metatarsal. In 50 percent of known cases, the deformity occurs bilaterally and in 33 percent of the cases, patients may have polydactyly of the foot and hand.^7,12

Polydactyly can be categorized according to its location in the foot. Preaxial (tibial) polydactyly is defined as a supernumerary digit of the first ray and/or the first interspace. Central polydactyly is referred to as an extra digit involving the second through the fourth ray. Finally, a postaxial (fibular) polydactyly, the most common type of polydactyly, is an extra digit of the fifth ray and/or the fourth interspace.⁵

There are three structural forms in which the extra digit can appear. Rudimentary polydactyly is a structural form that refers to the incomplete development of a digit without bone and may appear as a small, wart-like tumor. Complete polydactyly refers to a digit that is fully developed with full osseous development. The third structural form is polysyndactyly, which is defined as two adjoining digits that are fused together and one of the digits is supernumerary. Polysyndactyly also may be subcategorized based on the complexity of the deformity. When all of the bones are separated and all of the nail plates are separate, it is referred to as simple syndactyly. Complex syndactyly refers to bony fusions of adjacent structures and/or the nail plates have merged together.¹

Surgery is indicated in most cases of polydactyly to help alleviate pain, facilitate shoe gear, prevent toe deformities and for cosmesis. While one may perform surgery for a patient at any age with this condition, the ideal age for surgical intervention is between eight and 10 months.^10,12 At this stage, the patient is large enough to have surgery while allowing ample recovery time before the infant begins walking.

The most common surgical complication in all three types of polydactyly is removal of the wrong structure. One can avoid this through careful preoperative surgical planning.¹¹ Hematoma may occur if any segment of a metatarsal is removed. Clinicians can avoid hematoma by elimination of the dead space, use of a compressive dressing and intra-operative bleeding control. Necrosis may occur due to removing too much skin, thus causing excessive tension upon closure. Vascular compromise may occur by damage to the vessels of the toe or by a thrombosis of the vessels caused by careless dissection or rotation of the toe. Medial subluxation or valgus rotation is a common complication associated with post-axial polydactyly.² If a biphalangeal toe is present, surgeons should take care to salvage the larger and most functional segment of the two digits, usually the peripheral accessory bone. Foot function and stability should be the main goals of surgery, rather than salvaging the most cosmetically acceptable toe.²

Closing Thoughts

Although polydactyly is more common in the pediatric population, there are rare cases of the condition in adults.³ While surgical correction is common for all three types of adult polydactyly, it is important that the physician be aware of treatment challenges associated with surgery to allow proper pre-operative planning and prevent avoidable surgical complications.^1-12

Dr. Meneely is a third-year foot and ankle surgical resident at the Mount Sinai/Captain James A. Lovell Federal Health Care Center in Chicago.

Dr. Wu is the Dean, and Professor of Surgery at the Dr. William M. Scholl College of Podiatric Medicine, and Professor of Stem Cell and Regenerative Medicine at the School of Graduate Medical Sciences at the Rosalind Franklin University of Medicine and Science in Chicago. She is also the Director of the Center for Lower Extremity Ambulatory Research (CLEAR) in Chicago.

Dr. Lucas is the director of the Podiatric Surgical Residency at Mount Sinai/Captain James A. Lovell Federal Health Care Center in Chicago. He is a Fellow of the American College of Foot and Ankle Surgeons.

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