How To Treat Polysyndactyly And Syndactyly Of The Foot

Edwin Harris, DPM, FACFAS

   The concern here is damage to the physis of the fifth metatarsal located distally. With careful resection, the physis will probably continue to function normally. The possibility of lateral growth arrest with subsequent lateral deviation of the fifth toe is a real possibility. If the fifth metatarsal is Y-shaped, the medial portion may be adducted in relation to the proximal segment and its shaft components may be somewhat diminutive.

   There could also be some sagittal plane malpositioning with unacceptable plantarflexion or dorsiflexion. Resecting the lateral portion leaves a substantial amount of lateral cortical deficiency and makes additional corrective osteotomy at the same time somewhat risky since the osteotomy will occur near the “watershed” area of the metatarsal shaft. Fixation is difficult because of the loss of substantial lateral cortex and the possibility of delayed union or nonunion is very real because of its location in the shaft.

When Skin Grafting Is Necessary

In the separation of digital syndactyly and repair of the various forms of polydactyly, the surgeon must be prepared to perform a skin graft. There is usually enough skin to design a flap to cover one side of one of the toes but the adjacent side of the other toe will require a full thickness skin graft. Skin over the dorsolateral aspect of the sinus tarsi or the lateral ankle just anterior to the tendo-Achilles is a good cosmetic match. The groin is a good site as well but harvesting should happen in an area sufficiently lateral of midline so there is little risk of transplanting pubic hairs.

   Researchers have described many separation techniques that use multiple flaps plus a skin graft.29-31 Authors have described a technique for repair of polysyndactyly without the need for skin grafting.32,33 There are several reports in the literature describing the technique of allowing the exposed surface of the toe to granulate in.34,35

   In repairs that need skin grafting, a major concern is loss of the graft. This may occur because of excessive movement of the parts, the development of a hematoma or seroma under the graft, or failure to prepare the graft by appropriate debridement of all of the subcutaneous fat. It is advantageous to immobilize the part for several weeks in order to allow for vascularization of the graft. This can be very difficult in young children who are incapable of following postoperative protocol because of their age. Immobilization in a cast to minimize or prevent weightbearing is helpful. It is also helpful to operate when the patient is at an age when immobilization can be easily secured (perhaps before the patient begins ambulating or when the child is old enough to appreciate the gravity of the situation and is capable of cooperation).

   On rare occasions, keloid formation may occur. This is very difficult to manage.36-38 A possible solution is the use of methotrexate to minimize scar formation.39

   The surgeon must also consider the potential negative effects that harvesting the skin graft can have on the donor site. Unsightly scars can be a problem. Contractures of the scar at the donor site can be a major issue. Hyperpigmentation can also occur. Many skin grafts are harvested from the bikini area in the groin. There is a possibility of color and texture mismatch at the recipient site. The dorsolateral sinus tarsi followed by the areas between the tendo-Achilles and the malleoli match well, and morbidity is minimal as long as the surgeon avoids major nerves.

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