Introduction

Deep multicomponent wound defects of the distal leg, ankle and foot are traditionally considered as ones of the most difficult types of injuries requiring plastic closure [1, 2]. These defects may be caused by various lesions (trauma including gunshot wounds, postoperative necrotic and infectious complications, tumors, thermal injuries and vascular diseases) [3–5]. Common injury of deep anatomical structures (tendons, neurovascular bundles, joints and bone) excludes closure with free split or full-thickness skin grafts [1–6]. Despite the multiple available methods in plastic surgery, choice of optimal surgical strategy is still debatable. This is associated with advanced variability of defect characteristics (localization, area, depth, severity of damage to osteoarticular structures), deficiency of integumentary tissues in the distal parts of the lower limb, high functional requirements to foot supporting surfaces, prevalence of peripheral circulatory disorders [1–6]. Distally based sural flap is one of perspective options for repair. This approach was first described by P. Donski and I. Fogdestam in 1983, and then presented in detail by A. Masquelet et al. in 1992 [7, 8]. Incidence of postoperative complications is still high although a significant number of reports are devoted to refinement of angioarchitectonics and improvement of surgical technique [1, 2, 9–14]. The above-mentioned data inspired us to analyze own experience in closure of deep distal defects of the lower limbs with a sural flap.

The purpose of the study was to analyze closure of multicomponent distal defects of the lower extremity with a distally-based sural flap.

Material and methods

There were 21 patients who underwent closure of deep wound defects of the lower limbs with a distally-based sural flap. The sample included 19 (90.5%) men and 2 (9.5%) women aged 39.6±4.7 years (range 18–58). The defects were caused by high-energy mechanical injuries (n=8, 38.1%), gunshot explosive wounds (n=9, 42.9%), complications after osteosynthesis (n=2, 9.5%), complications of Achilles tendon suture (n=2, 9.5%). Injury following high-energy trauma was observed in 17 (81%) cases. In case of complications following osteosynthesis, an infected implant (plate) was visualized in the wound. Distal third defect of the lower leg (anterior ²/₃ of circumference) was observed in 9 (42.9%) cases, ankle joint — 4 (19.0%) patients, Achilles tendon area — 2 (9.5%) patients, heel area (back and plantar surface) — 4 (19.0%) cases, middle and forefoot — 2 (9.5%) patients. The defect area was 87±6.7 cm² (range 56-164). Bone fractures in different phases of reparation were observed in 16 (76.2%) cases. Closure was performed in 9-23 days after defect formation in patients with injuries and within 18 months in cases of postoperative complications. Risk factors of complications included smoking (n=15, 71.4%) and metabolic syndrome (n=4, 19.0%).

Preoperative examination included analysis of blood and urine, biochemical and X-ray data. Preoperative Doppler mapping was performed to verify patency of perforating vessels of the distal pedicle of the flap.

Prior to surgery, all patients were informed about interventions, possible risks and complications. Informed consent for surgeries, use of treatment data in research work and professional reports was obtained in all cases.

We used a standard technique of mobilization of a distally-based sural flap. Axial line of the flap was marked between the popliteal fold center and the line connecting posterior edge of the fibula and external edge of the Achilles tendon (Fig. 1).

Fig. 1. Preoperative mapping of a sural flap using a traditional technique.

Rotation point was marked at a distance of 5–6 cm proximal to the apex of external malleolus on the axial line of the flap. Flap dimensions were determined in accordance with dimensions of recipient defect with an excess of the outer border by 1–1.5 cm. Flap dissection was performed in patient’s prone position or lateral position under limb exsanguination. A transverse incision was made at the level of fusion of gastrocnemius muscle heads (border between the upper and the middle third of the leg). Dissection of superficial fascia was followed by identification, ligation and transection of small saphenous vein, superficial sural artery and sural nerve. A bordering incision outlined the flap skin area. Further dissection was subfascial. Pedicle of the flap 4–6 cm wide was formed up to the rotation point. The donor wound was closed via dissection of its edges in case of small defect or using combined skin grafting with a split flap. The limb was fixed by a plaster cast or an external fixation device. Lateral position was ensured in postoperative period to prevent flap compression. Infusion, antiplatelet, spasmolytic and phlebotropic therapy was performed for 3–5 postoperative days. Activation and verticalization of patients was carried out after 5–7 postoperative days.

All patients were divided into 2 groups depending on the method of flap pedicle dissection and its movement. In the 1^st group (n=9), traditional technique of dissection of fascial-adipose pedicle with subcutaneous delivery of the flap into recipient zone was used. In the 2^nd group (n=12), we used a modified technique of dissection of elongated fasciocutaneous pedicle and flap delivery through an open access (Fig. 2).

Fig. 2. Modified configuration of a sural flap with elongated fasciocutaneous pedicle.

Early and long-term (> 6 months) postoperative outcomes, incidence and structure of postoperative complications were analyzed. Statistical analysis was carried out using standard methods for small samples and Statistica 6.0 software package.

Results

Surgery time was 127±18 min (range 65–175) without significant between-group differences. No intraoperative transfusions were performed. Successful closure of wound defects was achieved in 20 (95.2%) cases. Subtotal flap necrosis occurred in 1 case of the 1^st group 1. There were no amputations. In the 1^st group, signs of venous insufficiency were detected in 4 (44.4%) patients after 2–3 postoperative days, that required partial removal of sutures and anticoagulant therapy. In 2 (22.2%) cases, we observed subepidermal blisters and partial desquamation of the epidermis. Marginal flap necrosis was formed in 3 (33.3%) cases, that necessitated redo surgery. In the 2^nd group, venous congestion occurred in 2 (16.7%) patients including 1 (8.3%) case of marginal necrosis followed by redo surgery. No infectious complications were observed. Partial wound dehiscence occurred in 3 (33.3%) patients of the 1^st group and 2 (16.7%) patients in the 2^nd group. Mean length of hospital-stay was 36.8±4.2 days (range 18–45) in the 1^st group and 23.2±3.7 days (range 18–27) in the 2^nd group (p<0.05). Long-term postoperative complications and negative treatment outcomes were absent. Anatomical and functional restoration of limbs was achieved in all cases.

Discussion

In recent decades, two approaches to plastic closure of deep distal tissue defects of the lower limbs have been formed (free microsurgical autotransplantation and plastic surgery with displaced regional axial flaps). Efficiency of free microsurgical autotransplantation is obvious and reaches 95% in specialized centers [3, 4, 15]. Its main disadvantages are technical complexity, need for expensive equipment, instruments and suture material, surgery time, necessary functional monitoring of the graft. As a result, these procedures may be performed only in few specialized centers with available material, technical and human resources [4, 5, 10]. The real need for closure of these defects in everyday clinical practice significantly exceeds the capabilities of single specialized microsurgical centers. An alternative is closure with the flaps mobilized from adjacent segments. This approach does not require microvascular anastomoses. However, this method has the advantages of free vascularized grafts (“guaranteed” blood supply and ability to vascularize the recipient zone, as well as innervation, multicomponent structure and wide variability of shapes and dimensions in some cases) [1, 2, 4, 5]. The advantages of this approach are relative technical simplicity depending on surgeon’s qualification rather technical equipment, no distant donor defects, less surgery time and lower costs) [1, 2, 16]. In this context, there are several possible options: insular compound flaps on the main arteries of the leg and foot, neurovascular cutaneous and fasciocutaneous flaps, “propeller” cutaneous and fasciocutaneous flaps, perforating cutaneous and fasciocutaneous flaps [12, 13]. Importantly, various authors attribute certain type of flap to different categories that results contradictions in terminology and understanding the peculiarities of blood supply and mobilization of the graft. Sural flap is one of the most common in modern clinical practice [1, 2, 10].

It is believed that a distally-based sural flap is supplied via the perforator vessels communicating posterior tibial and peroneal arteries with superficial sural artery accompanying sural nerve and saphenous vascular system [7–9]. Venous outflow is achieved via small saphenous vein and perforator veins. Obviously, retrograde venous outflow determines high likelihood of venous insufficiency. Indeed, venous insufficiency is the most common cause of postoperative complications after sural flap surgery [8, 9, 17]. Therefore, adequate venous outflow largely determines effective surgery. This objective can be realized via maximum decompression of the pedicle and imposition of additional veno-venous anastomoses [19]. The last method is described in the literature, but it is not clinically widespread. Traditionally, pedicle decompression can be realized via open passage of the flap through the wound with split skin grafting of pedicle, use of pedunculated configuration of pedicle or flap passage through a wide subcutaneous tunnel (Fig. 3) [18, 19].

Fig. 3. Passage of a sural flap through a subcutaneous tunnel.

a — subcutaneous passage of the flap; b — fixation of the flap during subcutaneous passage.

Our technical modification (group 2) implies an elongated fasciocutaneous pedicle of the flap that minimizes the risk of possible compression (Fig. 4).

Fig. 4. Closure of extensive calcaneal defect with a modified sural flap on elongated fasciocutaneous pedicle.

a — wound defect after secondary surgical debridement; b — displacement of the flap on elongated fasciocutaneous pedicle; c — result of plastic surgery.

Conditions for wound healing seem to be more favorable compared to fasciocutaneous pedicle covering with a split autologous dermal graft. Analysis of treatment outcomes in both groups revealed the advantages of the modified technique compared to traditional one. Thus, this approach may be recommended for further application.

The limitation of this study is small sample size that justifies further accumulation of clinical data and thorough study of this problem.

Conclusions

1. Sural flap is effective for closure of multicomponent distal defects of lower extremities.

2. The most common postoperative complication is venous insufficiency of the flap following compression of its pedicle.

3. Passage of the flap towards recipient wound through a subcutaneous tunnel is accompanied by significant risk of postoperative complications due to compression-induced venous insufficiency.

4. Elongated fasciocutaneous pedicle reduces the risk of possible complications and improves postoperative outcomes.

The authors declare no conflicts of interest.