The distally based sural flap is especially useful for reconstruction of complicated open wounds to the lower leg, ankle, and/or foot. The elevation of this flap is quick and easy to determine, however, it has been associated with complications, for example, postoperative venous congestion. There have been various studies and interpretations regarding the hemodynamics1–7. This flap, first described as the sural neurocutaneous flap by Masquelet et al8, is a skin-island flap supplied by the vascular axis of the sural nerve. Masquelet and colleagues popularized and renamed this flap the “sural neurocutaneous island flap,” in an anatomic study describing how the arteries accompanying superficial sensory nerves provide nutrient vessels to the skin as a source for the flap donor site1. Although the distally based sural flap is frequently preferred and is fairly reliable, some complications arising from poor circulation may be encountered with large flaps or with diabetic patients9–11.
Specifically, large flaps have been classically associated with a greater incidence of venous congestion leading to necrosis, despite adequate arterial perfusion10.
We report a modified distally based sural flap in the shape of a pedicle based on deep fascia, which we call a “round Japanese folding fan-like flap,” that decreases our complication rate because the modified flap promotes reverse venous return through existing adipofascial tissue.
Patients and methods
A retrospective chart review was conducted on patients who underwent distally based sural flap reconstruction from 1994 to 2018 in Saga university hospital and related hospitals. We treated 25 patients (17 men and 8 women) who had different etiological causes such as malignant tumors, trauma, osteomyelitis of the heel, and/or diabetic foot ulcers/gangrene.
The patients varied from 6 to 84 years old with a mean age of 50.8 years. There were 16 fasciocutaneous flaps and 9 fascial flaps. The recipient sites were distal to the lower one third of the leg, ankle and/or foot such as the plantar region including the heel and the dorsum of the foot in all patients. There were 5 patients who smoked, 6 diabetes mellitus patients, no venous insufficiency patients, and 2 peripheral artery disease patients (Table 1).
Table 1 -
Characteristics of patients and results
|Sex: male, n (%)
|Age (range) (y)
|Smoking history, n (%)
|Diabetes mellitus, n (%)
|Peripheral artery disease, n (%)
|Venous insufficiency, n (%)
|Etiology of defect, n (%)
| Malignant tumor
| Diabetic foot ulcer/gangrene
| Osteomyelitis of the heel
|Location of defect, n (%)
| Anterior side of the leg
| Dorsum of the foot
|Size of flap: length, mean (SD) (cm)
|Width, mean (SD) (cm)
|Survival of flap, n (%)
|Delayed procedure of flap, n (%)
|Complication, n (%)
| Partial loss: in standard manner before 2000
Surgical procedure: flap design and surgical technique
This flap can be planned anywhere in the lower two thirds of the leg. With the patient in prone position, the dimensions of the defect are measured, and a line is drawn from the popliteal fossa to the Achilles tendon on the posterior aspect of the leg as a flap axis, preoperatively. Lateral malleolus and pivot points located 5 cm above the tip of the lateral malleolus are marked as previously described8,10–12.
The distance from pivot point to the nearest border of the defect determines pedicle length and flap location. From now on, it is easy to place the flap on the flap axis. Standard distally based sural flap reconstruction before 2000 had dimensions equal to the defect (Fig. 1). Since 2000 flap dimensions have been enlarged to make it a little bigger than the defect. For example, the fascia around the island skin area is enlarged by 2–3 cm from the distal to the proximal area and is recentered over this new line. The shape of this design is a so-called, “round Japanese folding fan-like flap”(Fig. 2 left). Doppler testing may be useful for predetermining the septocutaneous perforators of the peroneal artery in the distal part of the tibiofibular space. It is necessary to check the perforator’s sound because when the patient suffers from peripheral arterial disease, the Doppler sound is missing or weak. A skin incision is begun on the upper border of the flap and dissection can be performed without a pneumatic tourniquet. It should be remembered that the medial sural nerve and its accompanying artery, called the median superficial sural artery, and the lesser saphenous vein, course through the subfascial plane in the upper third of the leg. With the incision made through the underlying deep fascia, which is included in the flap, these two anatomical structures are identified and severed (Fig. 2 middle). Although the accompanying artery is not always seen, it is vital to determine the location of the medial sural nerve and to include it in the flap. Failure to do so creates a flap lacking a nerve and artery elevated as an unipedicled venous flap based on the lesser saphenous vein. The skin island is incised circumferentially and the flap subfascial dissection proceeds from a proximal to distal direction (Fig. 2 middle). In the distal portion, a skin incision over the pedicle is performed to the pivot point, although the pedicle can be transferred with the skin bridge over itself. The pedicle width should be at least 4 cm. Although the pedicle can be exteriorized, we prefer to transport it via an incision between the pivot point and defect (Fig. 2 right). The surface of a pedicle and flap donor site is usually skin-grafted to prevent postoperative venous congestion of the flap.
The mean flap size was 12.0 cm×7.0 cm (range: 7–20 cm×3–13 cm). All flaps from among the 5 patients treated with standard distally based sural flap reconstruction before 2000 survived although one flap suffered from partial necrosis due to venous congestion. None of the other 20 patients treated with the round Japanese fan-like flap developed either partial or complete flap necrosis because of venous congestion. No other complications concerning the flap or donor site were observed (Table 1).
All patients began to walk again, during the follow-up period and there were no subsequent ulcerations of the flap. All flaps revealed good durability and no debulking procedure was required. Donor areas in 15 cases were closed with skin grafts. All donor areas healed with moderate scaring. As for major donor site morbidity rates, numbness on the lateral side of the foot was observed in all patients. There was no need for a secondary procedure to divide the pedicle and return it to the donor site after the initial flap inset.
A 52-year-old men was admitted with a large wound defect of the foot caused by diabetic foot gangrene (Fig. 3A). After the patient was transferred to our hospital, negative pressure wound treatment was performed for debridement of the gangrene (Fig. 3B). A round Japanese fan-like flap as a distally based sural flap measuring 13 cm×8 cm was used with a delayed flap procedure that raised and applied bone exposure with a good wound bed (Figs. 3C, D). The flap donor site and distal area of foot defect after pressure wound treatment were covered with a split-thickness skin graft (Fig. 3E) and the entire flap survived. The patient became ambulatory, with footwear, at 4 weeks, postoperatively. The antero-lateral view of the right lower leg and foot shows the positive result of the procedure (Fig. 3F and Supplemental Digital Content, Video 1, http://links.lww.com/IJSGH/A7).
No complications were encountered in the postoperative follow-up. (Patient has provided informed consent for publication of the case.)
A 61-year-old man was admitted with an acute traumatic defect of the anterior aspect of his right leg after a road-traffic accident. There was exposure of the anterior tibial muscle-tendon (Fig. 4A). A round Japanese fan-like flap, as a distally based sural flap measuring 10 cm×4 cm, was raised and used to cover the surrounding tendon area with deep fascia (Figs. 4B–D). The flap donor site, including the pedicle of the flap, was covered with a split-thickness skin graft (Fig. 4E). The entire flap survived. Postoperative complications such as edema or venous insufficiency were not observed. The antero-posterior view of the bilateral lower leg shows positive results with full dorsal flexion of the ankle at 4 months, postoperatively (Figs. 4F, G). (Patient has provided informed consent for publication of the case.)
Elevation of the distally based sural flap is quick and easy to determine, even if the total size and/or shape of a flap that can be elevated safely is still uncertain12. One interesting aspect of the distally based sural flap is its arterial supply and venous return pathways. The distally based sural flap flap relies on its retrograde blood supply by means of distal sources rather than the proximal anterograde supply. There are at least 4 sources of this retrograde blood supply: fasciocutaneous perforators from the peroneal artery; fasciocutaneous perforators from the posterior tibial artery; venocutaneous perforators from the lesser saphenous vein; and, neurocutaneous perforators from the sural nerve2,5,6,13.
Inclusion of the sural nerve and lesser saphenous vein in the flap provides 2 sources of arterial supply. This is in addition to the fascial plexus supplied by the 2 groups of septocutaneous perforators. Although the lesser saphenous vein contains numerous valves that prevent retrograde blood supply, there are one or more collateral veins, with relatively weak valve resistance, that can be used as drainage pathways. These veins run parallel to the lesser saphenous vein and have anastomic connections that allow blood to flow in a retrograde manner bypassing the valves of the lesser saphenous vein7. Because drainage pathways for the flap are provided entirely by these concominant veins of the lesser saphenous vein, it is important to plan a distal-based sural flap that prevents venous congestion. In cases were the width of the flap is >4 cm, the size of the venoadipofascial pedicle distal from the flap should be as large as possible.
The round Japanese fan-like flap (shaped from the pedicle to the distal area of the flap) promotes reverse venous return through existing adipofascial tissue thus preventing flap necrosis from developing. Another option is to use the anastomosing lesser saphenous vein. It is separated proximal to the skin paddle to a subcutaneous vein and this technique has been proven effective for the survival of the flap. Venous congestion of the flap can be prevented because venous anastomosis allows venous blood to flow through the venous valves. The effectiveness of this anastomosis have been reported by Tan and colleagues2,9. Recently, Kishi et al14, reported its significance in a distally based greater saphenous venoadipofascial-sartorius muscle combined flap with venous anastomosis.
The round Japanese fan-like flap (distally based sural flap) increases reconstructed ankle function and can also result in fewer complications, for example, postoperative venous congestion. It is also useful for reconstruction of open wounds of the leg and/or foot. Because it promotes reverse venous return through existing adipofascial tissue, development of flap necrosis is prevented. Another merit of this flap is that ankle function can be restored by using deep fascia in a wrapping technique of exposed muscle-tendons. This blood circulation-enriched fascia is also useful for treatment of bone exposures and/or osteomyelitis of the ankle.
Sources of funding
Conflicts of interest disclosure
The authors declare that they have no financial conflict of interest with regard to the content of this report.
Research registration unique identifying number (UIN)
The authors thank Dr Yoshikawa A. in Kumamoto rehabilitation hospital and Yokota K. in Hiroshima University hospital for affirmative review about clinical cases.
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