The Wraparound Flap

It has been devised for improving appearance of the reconstructed thumb thus giving the possibly to create a «custom made» new thumb.

This is feasible through a combined tissue flap including part of the distal phalanx with the corresponding part of the nail, an extended flap with dorsal and plantar skin narrowed down to the size in which the soft tissue flaps can wrap it around. No joint or epiphysis is incorporated and has no growth potential. Therefore this procedure is not indicated in children. It is also a prerequisite for the stump to have a functioning MCP joint if we want to retain mobility of the reconstructed thumb (Fig. 9.1).

The wraparound procedure is performed in four steps. First, after measuring the length and the circumference of the normal thumb and the size of its nail, we transfer these dimensions on the lateral side of the ipsilateral toe. The incisions are marked on the skin and the nail, and the cutaneous strip is left on the medial side of the great toe.

Secondly the dissection starts at the dorsum of the foot with identification of the dorsalis pedis artery. Then, following its course it descents down to the first dorsal metatarsal artery until it reaches the base of the great toe. Following, the skin flap is dissected and detached from underlying tissues as a degloving, including the digital nerves and the whole nail phalanx.

Particular attention should be paid to avoid disruption of the germinal matrix at the dissection of the nail with the underlying bone. The dorsal venous system should also be protected into the dorsal skin flap. At the donor site, the paratendon should be retained on the extensors thus allowing coverage with skin grafts.

The final wraparound transplant should include a composite tissue flap made out of the most part of the great toe skin, nail and distal phalanx with a dorsal venous system, two digital nerves and the lateral digital artery as an extension dorsa-lis pedis and the distal branches of the dorsal peroneal nerve (Figs. 9.2 and 9.3).

To create a «custom made» thumb, a tricortical bone graft from the iliac crest is harvested sized and shaped up so that the length of the contralateral thumb is accomplished. The skeleton of the new thumb will be completed now with the base of the 1st phalanx proximally, the trimmed part of the distal phalanx of the great toe distally and an interposed graft from the iliac crest. Adequate fixation with either 2 K.

Fig. 9.1. Thumb amputation near the base of the 1st MCP.

wires or miniature plates and screws, is necessary to secure stability until bone healing and graft incorporation is achieved

The nail of the transplant also needs trimming until its size approximates the contralateral one. The nerves, veins and arteries are suture to the previously prepared recipient site structures and finally the skin is closed. The paronychial skin folds at the radial side of the transplant is shaped and sutured with the skin edge inverted towards the nail edge thus covering its radial side (Fig. 9.4 and Fig. 9.5).

Closure of the Donor Site after Dissection of the Wraparound Flap

The remaining skin at the medial side of the donor great toe is inadequate to cover the soft tissue defect. We prefer to shorten the remaining skeleton down to the middle of the 1st phalanx so that this skin flap covers the distal and the plantar aspect

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