SURGICAL RECONSTRUCTION TECHNIQUE OF TWO PATIENTS WITH TARSAL TYPE PREAXIAL POLYDACTYLY: TWO TRUE PREHALLUCES
INTRODUCTION: Limb anomalies are relatively common and of these, polydactyly of the foot occurs in 1.7 cases per 1000 live births, comprising 45% of congenital abnormalities of the foot. The majority of reported polydactyly cases of the foot are postaxial, only 15% are preaxial polydactyly and tarsal type preaxial polydactyly (a true prehallux) occurs in only 3% of preaxial polydactyly cases. Due to the rarity of tarsal type preaxial polydactyly, there is minimal literature available to guide management. Potential treatment options include observation, shoe modification to accommodate the extra digit, a simple surgical resection of the extra digit by cutting all attaching structures, or a surgical resection with identification of the extra extensor tendon going to the extra digit and transfer of this tendon to the remaining foot near its normal insertion.
CASE HISTORY: Two newborns presented with similar tarsal type preaxial polydactylies in the context of VACTERL syndrome at a single institution. Patient 1 initially presented at birth with an accessory digit arising medially from the right foot at what appeared to be the level of the medial malleolus. Two weeks later, seemingly unrelated, patient 2 presented at birth with an accessory digit arising medially from the right foot at what appeared to be the level of the navicular. Due to concerns regarding interference with shoewear and cosmesis, both patients underwent resection of the extra digit and reconstruction including transfer of the accessory anterior tibial tendon arising from the preaxial extra digit to the remaining first ray. Two years following surgery both patients are walking well with preserved dorsiflexion strength. One patient utilizes a supramalleolar foot orthesis to support flexible hindfoot valgus, and both are able to wear shoes without difficulty.
DISCUSSION: Given the rarity of publications of similar cases with surgical treatment and outcomes reported, this case report demonstrates the management of these two patients to better guide future patient care. While nonsurgical treatment with shoewear modification is an option, surgical reconstruction facilitated wearing typical shoes while preserving ambulatory ability. It is important to note that both patients in this series had an accessory anterior tibial tendon, and this tendon appeared to be the dominant dorsiflexor of the ankle in one patient. Transferring this tendon during surgical reconstruction, rather than simply releasing it, prevented loss of dorsiflexion strength and foot drop postoperatively.