Abstract
Soft tissue defects of the lower extremity pose an important surgical challenge, often because of inviability of primary covering. Therapeutic modalities of choice comprise of local perforator flaps, as well as of free flaps created with the use of microsurgical skills. However, these methods cannot be applied in patients with important comorbidities, and it is in such cases where the reverse sural flap proves to be the best solution. the aim of the study was to present the results of treating lower extremity defects with various modifications of the reverse sural flap. material and methods. Sixteen patients, males aged 17-56 years, were operated on from 2007 to 2013. Diabetes with multiple complications, disseminated atheromatosis, and extensive soft tissue trauma involving the arteries crucial for microsurgica anastomoses were the most common reason disqualifying from the free and perforator-based flap techniques. results. All of the patients achieved very good results; in two cases distal and marginal flap necrosis was observed which, once exiced, covered with granulation, and was successfully covered with a partialthickness skin graft. conclusions. The reverse sural flap, technically easy, offers a viable, low-risk alternative to free and perforator-based flaps.

The reverse flap based on the median sural superficial artery accompanying the cutaneous sural nerve and the sural vein is an old, timeproven method still in use. Although Hamilton pioneered its application in 1854, it was not until 1932 when Gillies described it as a modality for covering defects of the lower third of lower extremities with a pediculated fasciocutaneous flap from the contralateral limb (1) . Eversince, various modifications of this technique have been described in both Polish and international medical literature. The most common modifications comprise of: 1) cross-leg / crossed pediculated fasciocutaneous flap from the contralateral limb covering the defects of the other limb, 2) pediculated reverse flow fasciocutaneous flap covering the defects of the ipsilateral limb,

3) island reverse flow fasciocutaneous flap as big as 10x12 cm covering the defects of the lower third of the ipsilateral limb. Virtually all of the abovementioned varieties are used in the reconstructive surgery of the lower limbs. The ease of operative technique makes it the method of choice in nonhealing wounds of the distal calf, with the pedicled flap from the contralateral limb being the most inconvenient for the patient due to the unnatural positioning for ca. 3 weeks. Thanks to its long pedicle the reverse flow sural flap can be transferred as far as the dorsal part of the foot, as well as the proximal part of the sole. Usually simple partial-thickness skin grafting suffices to cover the donor site.

The superficial sural intermediate artery comprises the main vascular axis of the flap; however, the supply of the peroforators of the posterior tibial and sural artery play some role. The superficial intermediate sural artery courses along the cutaneous sural nerve and the sural vein between the two heads of the gastrocnemius muscle, where the neurovascular pedicle is cut off and subsequent distalward dissections produces a long, mobile, easily rotated flap. In case of the island flap, the donor site can be closed primarily if the defect does not exceed 3 cm; greater defects must be covered with partial-thickness skin graft. Moreover, the pedicle of this flap may additionally be based on the perforators of the tibial posterior and sural arteries. The two other flaps virtually always require the donor sites to be covered with partial-thickness skin graft. After 3 weeks the pedicled flap should be remodelled in such a way as to prepare the pedicle to cover the distal part of the donor site, a procedure which ensures that the donor site partially recover its original tissues. As for the first variety, several methods of immobilizing the lower limbs were described: initially, the legs were fixed with plaster cast; other method involved an external stabilizer for 3 weeks. We decided to apply a soft immobilization which provides better comfort and tolerance.
MATERIAL AND METHODS
Sixteen males, aged 17-56 years, were operated on from 2007 to 2012 using the first and second modification of the flap because of the patients' significant comorbidities or. Almost in all of the cases there were defects of the lower third of the lower limb accompanying posttraumatic disfigurations, bone/tendonexposing wounds, bedsores, ulcers, and diabetic feet.
MATERIAL AND METHODS
In our opinion this therapeutic modality was the best solution, carrying the lowest risk of complication and failure. Our observations confirm good tolerance of 3-week-long unnatural leg positioning. Table 1 provides detailed description of defect localization and the type of flap used.
RESULTS
All of the patients achieved good results. Two cases where distal marginal necrosis of the flap developed were managed by central necrosectomy and defect coverage with a partial thickness skin graft. The cross-leg flaps resulted in stricture-free healing, and the three-week immobilization period was tolerated very well.
DISCUSSION
The method of covering limb defects with pedicled cross-leg flap from contralateral limb has been accepted by modern medicine in 1946, when it was described by Stark (2). Its main advantages include the technical ease, well tolerance by the patients, and the low rate of complications. The medical literature abounds with studies evaluating this method and its results in patients with post-traumatic softtissue defects of the distal third of the lower limb (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) . Later on, with the progress of microsurgical skills and better understanding of the versatility of local pedicled, free, as well as perforator flaps, the cross-leg flap lost its label "of choice", and became either a means of the last resort, or, in select cases only, an alternative to other reconstructive methods (18) (19) (20) (21) (22) (23) . In some instances, the cross-leg flap bases on other vessels (24, 25, 26) , a fact which enabled this flap to cover limb defects at various levels. The method of immobilization, for the commonly accepted 3 weeks, varied from plaster cast, through external fixator, to traditional soft dressing.
DISCUSSION
Some studies report even earlier cutting the flap off with no complications (27). Another variation of the classic method comprises of the cross-leg venous anastomosis of Fig. 1 . The case of a 17-year-old boy following the fracture of both tibia and fibula, subsequent compartment syndrome, and fasciotomy. A -completely exposed tibia and its internal fixation, Bafter transferring the cross-leg flap, C -the donor site covered with a free partial-thickness skin graft, D -end result 2) good esthetic results, 3) no need for unnatural immobilization, 4) capability of being used as a rotated, perforator-based local flap, or a free one to cover distal defects, 5) capability of being used in pediatric patients (36) (37) (38) (39) (40) .
CONCLUSIONS
1. Soft-tissue defects of the lower limb still poses a significant therapeutic challenge. 2. The method of choice in case of soft-tissue defects of the distal third of the lower limb are perforator-based and free flaps, tranferred microssurgically. However, whenever this method is associated with high risk of failure, the local pedicled as well as cross-leg flaps based on the sural neurovascular pedicle should be considered as the optimal solution.

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