Materials and Methods
Between December 2009 and December 2012, 18 patients (10 males) at the Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology (Wuhan, China) underwent surgery for soft-tissue defect reconstruction using a proximally based sural fasciocutaneous flap. All patients gave written, informed consent, and the study was approved by the ethical committee of the hospital. All surgeries were performed by the corresponding author. The average age of the patients at the time of surgery was 38.6 years, and the median follow-up time was 16 months (range: 4–24 months). Defects were located around the knee in 3 cases and on the proximal half of the lower leg in 15 cases. Road traffic accident was the cause of the soft-tissue defects, including acute soft-tissue necrosis in 12 cases and postoperative internal hardware exposure in 6 cases. Associated risk factors were diabetes, advanced age, cigarette smoking, and high blood pressure. The flap size ranged from 8 x 7 cm to 16 x 12 cm and the pedicle length ranged from 12 cm to 18 cm (Table 1).
Surgical Technique
Patients were positioned prone or lateral and a tourniquet was placed in the proximal thigh and pressurized without exsanguination. The venous congestion could facilitate the identification and dissection of the neurovascular structures. A radical debridement of the recipient region should be performed before flap transplantation.
Anatomically, the proximally based sural fasciocutaneous island flap consisted of an islet of skin and subcutaneous fat, the superficial and deep fascia, sural nerve, lesser saphenous vein, and the superficial sural artery. The flap circulation mainly depended on the median superficial sural artery, which mostly originated from the popliteal artery.
Initially, a line was drawn on the posterior calf to indicate the course of the sural nerve and adjacent lesser saphenous vein, usually extending from the midpoint of the lateral malleolar tip and Achilles's tendon to the midpoint of the popliteal skin crease. The donor site was centered on this line, which also roughly marked the course of the pedicle. The pivot point of the pedicle was usually set on the line 1.5 cm to 2 cm distal to the popliteal skin crease, where it was about 1.5 cm away from its origin of the sural artery. A skin islet was drawn by 15% enlargement of the dimension of defects in the form of a paddle, with 2 cm increment of pedicle length and with about 3 cm pedicle width (Figure 1).
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Figure 1.
After measurement of the size and shape of the recipient site, the pivot point and pedicle length were determined and the donor site was designed centered on the line on the posterior calf indicating the course of the lesser saphenous vein and sural nerve.
Thereafter, the entire flap was dissected and elevated from distal to proximal. Initially, the skin and subcutaneous fascia were dissected distally to incorporate the deep fascia, the ligated lesser saphenous vein, and the sural nerve together. The lesser saphenous vein is always superficial, but the sural nerve penetrates the deep fascia at the midpoint of the lower leg and then follows a course between the 2 heads of the gastrocnemius muscle. The proximal neurovascular structures should be always carefully dissected so as not to damage them, especially the proximal sural nerve. Sometimes, the central axis of the flap and its pedicle were adjusted so as to include the sural nerve, the lesser saphenous vein, and the nearby sural artery when any of the neurovascular structures significantly diverged from the course line. Interrupted suture between the skin and the subcutaneous deep fascia was required to prevent sliding of both layers. Finally, the entire flap was elevated between the deep fascia and the aponeurosis of Achilles's tendon or gastrocnemius muscular fascia on the posterior calf until reaching the pivot point.
A blunt dissection near the pivot point should be carefully performed so as not to damage the incorporated median sural artery. Once the flap was entirely evaluated, the tourniquet was deflated and the flap circulation was checked. Occasionally, a hot pack with warm normal saline was used to relieve spasm of the vessels incorporated in the pedicle. After verifying good circulation of the flap, an open tunnel was incised and, through the tunnel, the flap and its pedicle were transposed laterally or medially to the recipient defects by careful rotation over the pivot point, avoiding both torsion and tension. After attachment to the recipient defects, the flap was sutured with no tension.
The donor sites were all closed in one stage with split-thickness skin graft. The vacuum sealing drainage technique was routinely used to achieve effective compression to the grafted skins. The drainage strips were put around the flap and its pedicle to allow bleeding. Generally, external supports were not used due to possible compression to the flap, however, patients were not permitted to vigorously move their knee joints during the first 5–7 days following surgery. The drainage strips were taken away 48 hours postoperatively and the vacuum sealing drainage dressing was removed 7–10 days postoperatively.