The results of this study show that the reverse sural neurocutaneous flap is an effective method to resurface soft tissue defects around the foot and ankle region.
We would recommend some measures that we adopted in our cases and which have been advised in the literature to ensure safe flap elevation and improve the venous congestion of the flap, hence decrease the risk of failure.
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1)
Preoperative identification of the peroneal artery perforators by Doppler should be performed and the peroperative search for a perforator should be avoided which can be potentially dangerous [1].
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2)
A 'modified plaster of paris boot' (Figure 1), that we describe in our cases can be used to avoid pressure on the pedicle in the postoperative period. This helps the patients to remain supine, allows assessment of the flap circulation and assists in the elevation of the foot to relieve venous congestion.
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3)
The pedicle should be kept wide (3 to 4 cm.) [1, 3] and skin grafting should be done on the pedicle if the subcutaneous tunnel becomes tight and impairs circulation. In our series, in nine out of ten patients the pedicle was passed through an open tunnel and skin grafted. Although skin grafting added slightly to the donor site morbidity, it prevented pressure on the pedicle in the post operative period.
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4)
The lesser saphenous vein should be included in the pedicle in all cases [2].
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5)
There are a few studies in which this flap is used to cover defects in the distal part of the foot by slight modification of the flap design, by inclusion of the midline cuff of gastrocnemius muscle, in flaps harvested from proximal calf area [4]. We performed one flap in this manner to cover the medial aspect of the midfoot in an old lady with diabetic ulcer (Figure 2A and 2B). We postulate that the whole skin of the posterior calf can be harvested without any major problem. Sural neurofasciocutaneous flaps as large as 17 × 16 cm. have been reported [5].
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6)
Leech therapy can also be used to decrease venous congestion [6]. We did not require the use of leech therapy in cases of reverse sural neurocutaneous flaps but did found it of use in a reverse flow saphenous neurocutaneous flap.
Anastomosis with one of the donor veins from the foot may also be an alternative, but we do not see the need for this intervention at the moment.
The vascular anatomy and clinical application of the reverse sural neurocutaneous flap has been well studied [2, 7–10]. The artery existed as an axial pattern vessel in only 50 percent of our patients.
Self limiting numbness in the distribution of sural nerve is not a major concern. The patients should be counselled preoperatively and the problem is usually resolved on an average in three months in all patients. To avoid a painful neuroma, the nerve stump needs to be buried in the deep muscular plane.
Donor site morbidity was minimal in our patients. Unaesthetic donor site, perhaps, may be a major concern to the young female patients. It can potentially be avoided by using an adipofascial flap, rather than harvesting skin island in larger flaps.
Future Concern
Based on the sensate character and same quality skin, medial plantar flap has been proposed to be superior for heel coverage over sural artery reverse flow flaps [11, 12]. However no substantial clinical or laboratory data is available for reinnervating the reverse sural artery flaps. Reverse flow homodigital island flaps for finger tip injuries have been rendered sensate by including a segment of palmar digital nerve in the flap design and anastomosing it to the opposite side digital nerve [13–15].
Based on the above observations we postulate end to side anastomosis of the sural nerve to a plantar digital nerve, in order to provide sensory reinnervation to the flap especially in cases of weight bearing heel reconstruction.
