Vastus Lateralis Free Flap for Soft Tissue Coverage of a Lower Extremity Diabetic Ulcer

The use of free tissue transfer with muscle flaps, followed by coverage with skin grafts, is currently an accepted treatment for lower extremity diabetic ulcers in need of soft tissue coverage. Despite the increased incidence of arteriolar occlusive disease in diabetic patients, it has been shown that peripheral microsurgical free flap anastomosis provides a sufficient blood supply for flap survival until neovascularization at the recipient site occurs.[1] Flap survival in such cases is comparable to that of free flap surgery in nondiabetic patients, and effective infection control can be achieved.[2] Among the free muscle flaps described for such a purpose are the rectus abdominis, gracilis, latissimus dorsi, and the cross-leg pedicled free scapular flap.[3] [4] [5] We describe a case of a partially amputated foot secondary to diabetic ulcer, treated successfully with debridement and an ipsilateral free vastus lateralis muscle flap. Subsequent muscle coverage was provided by a split thickness skin graft.

A 45-year-old male with new onset non-insulin-dependent diabetes mellitus presented to our institution for treatment and reconstruction of a right foot surgical defect. Two days prior to this, he presented to an outside hospital with a 15 cm × 20 cm necrotic ulcer on the lateral dorsum of his right foot, which had progressed to wet gangrene of the involved area. There, he was taken to the operating room, where the wound was acutely debrided, and the lateral three distal phalanges, proximal phalanges, and metatarsals were all amputated. A JP drain was placed, and the wound was closed primarily. Intraoperative cultures grew Escherichia coli, and the proper antibiotic coverage was started. The patient was then transferred to our hospital for further debridement and reconstruction. He was taken to the operating room, where examination under anesthesia revealed an odorous and wet gangrene on the lateral dorsal aspect of the right foot. All sutures were removed, as was the drain, and the involved skin, subcutaneous tissue, muscle, and bone were debrided extensively to provide a bed of healthy granulation tissue (Fig. [1]). Following this, the wound was closed with vacuum-assisted closure device placement. The patient was then maintained on this wound closure device, while being treated with vancomycin, rocephin, and metronidazole.

Figure 1 Foot wound, preoperatively.

He was then returned to the operating room on day 5 for wound reconstruction with an ipsilateral vastus lateralis free tissue transfer. Consideration was given to performing a cutaneous free flap reconstruction; however, due to the size of patient and the thickness of the ALT skin paddle (which was greater than 4.0 cm), a free vastus lateralis muscle flap was decided upon. Initial anatomic exposure of the dorsalis pedis vessels showed these vessels to be involved in the infection of the dorsal foot. Thus, the anterior tibial vessels were identified more proximally, and chosen as the recipient vessels for anastomosis. On the anterior thigh, an incision was made to the level of the junction between the vastus lateralis and the rectus femoris muscles. This was dissected down to the descending branch of the lateral circumflex femoral artery and veins, which were visualized to have several branches supplying the vastus lateralis muscle (Fig. [2]). A 15 × 25 cm portion of the muscle was harvested distally, along with a 13-cm long vascular pedicle consisting of the arterial and venous lateral circumflex femoral system, as well as the supplying motor nerve branch from the femoral nerve (Fig. [3]). Microanastomosis was then performed, using the anterior tibial vessels as the recipient vessels. The vein was anastomosed in an end-to-end fashion, followed by the artery in an end-to-side fashion. Once adequate blood flow was achieved, the muscle was contoured to fill the bony defect, and sutured into place over the pedicle. A 14/1000 inch split-thickness skin graft was harvested from the ipsilateral thigh, and placed over the muscular free flap on the lateral dorsum of the foot. The foot was bandaged, and immobilized in an orthosis.

Figure 2 Exposure of vastus lateralis and supplying descending lateral circumflex femoral artery and vein 1 Descending branch of the lateral circumflex femoral artery/vein. 2 Antero lateral thigh (ALT) vascular pedicle. 3 Motor branch of femoral nerve. 4 Vastus lateralis. 5 Vastus intermedius. 6 Rectus femoris.

Figure 3 Elevation of vastus lateralis flap with attached pedicle.

The immediate postoperative period was uneventful. University of Rochester monitoring protocol with Doppler checks was instituted and indicated a healthy blood supply. Two weeks later, the flap was viable, with well-healing skin edges, and 100 percent take of the overlying skin graft (Fig. [4]).

Figure 4 Healing, viable free tissue coverage of original foot defect 3 months postoperatively.

The flap survived completely, indicating successful neovascularization in the recipient site. The only postoperative complication was noted 6 weeks postoperative after compression dressings were initialized and a small portion of the skin graft was lost. However, the underlying muscle flap was healthy and viable, and the area was treated with local wound care. The patient at this time was tolerating small weight transfers on the right foot, but was not yet advanced to weight-bearing activity. He went on to full recovery and ambulation never requiring a second operation. He currently is actively employed.

Diabetic patients with neuropathic foot ulcers benefit greatly from soft tissue free flap coverage to involved areas, particularly when underlying bone is exposed. Despite a compromised peripheral blood supply secondary to arteriolar occlusive disease, free flaps remain viable to a high degree when provided with an adequate anastomosis.[2] The transplanted muscle serves both to decrease the risk of underlying osteomyelitis, as well as to provide a rich blood supply for antibiotic penetration. Such lower extremity defects have in the past most commonly been treated with free rectus abdominis or latissimus dorsi flaps. We believe that this is the first description, although certainly not the first use, of the free vastus lateralis flap for such a lower extremity reconstruction. With regard to its use as a free flap, the vastus lateralis has been described primarily for use in the head and neck region. Common uses include correction of cranial base defects such as exposed dura and cerebrospinal fluid leaks, as well as intraoral reconstruction following tumor ressection.[6] [7]

The vastus lateralis free flap has several advantages as a free flap for lower extremity reconstruction. Because of its location, supine positioning of the patient can be advantageous for anterolateral defects, which are often in need of free tissue transfer without changing the positioning of the patient. The vastus muscle also has a long consistent vascular pedicle with very large vessels for anastomosis. The average pedicle length is between 13 and 20 cm and the vessels are the largest branch off the profunda femoris in the thigh, with the artery measuring 2 to 2.5 mm and the vein(s) 2.5 to 4.0 mm. These portions can be further debulked by primary thinning of the epifascial fatty tissue, resulting in an extremely versatile free flap.[8]

Similarly, the use of the vastus lateralis free flap for lower extremity reconstruction carries many advantages. If skin graft coverage of a free muscle flap is not the preferred method, the muscle can also be raised with the overlying subcutaneous tissue and skin, to provide an anterolateral thigh myocutaneous flap. The use of such a flap for reconstructive use in many parts of the body has been widely described. As a member of the quadriceps femoris muscle group, the vastus lateralis carries out an action synergistic to that of the vastus intermedius, the vastus medialis, and the rectus femoris muscles. Thus, harvesting this muscle for its use in free flap reconstruction leads to minimal incidence of any functional impairments at the donor site, and the stability of the ipsilateral knee is not affected. Functional assessments of the muscle function in patients following vastus lateralis harvesting have shown no significant change in the ability of the quadriceps group to produce power or torque, and only a slight impairment in force of contraction.[9] Furthermore, in the event of poor perforator vessels to the ALT skin island, the muscle supplied by the descending lateral circumflex femoral vessels can be used reliably. One may also note that if problems arise during the harvest of this flap, there is no need to raise additional free flaps from other anatomic sites.

The vastus lateralis free flap provides an excellent option for reconstruction of lower extremity ulcers in diabetic patients. Its long neurovascular pedicle offers the surgeon a great deal of flexibility with potential recipient vessels in the legs, and its large size offers the potential for coverage of various sizes and numbers of defects.

REFERENCES

• 1 Oishi S N, Levin L S, Pederson W C. Microsurgical management of extremity wounds in diabetics with peripheral vascular disease.  Plast Reconstr Surg. 1993;  92 485-492
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• 3 Musharafieh R, Macari G, Hayek S, El Hassan B, Atiyeh B. Rectus abdominis free-tissue transfer in lower extremity reconstruction: review of 40 cases.  J Reconstr Microsurg. 2000;  16 341-345
• 4 Rainer C, Schwabegger A H, Meirer R, Perkmann R, Ninkovic M, Ninkovic M. Microsurgical management of the diabetic foot.  J Reconstr Microsurg. 2003;  19 543-553
• 5 Hamdi M, Weiler-Mithoff E M, Webster M H. Cross-leg pedicled free scapular flap for neuropathic foot ulcer: case report.  J Reconstr Microsurg. 2000;  16 597-601
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• 7 Wolff K D, Howaldt H P. Three years of experience with the free vastus lateralis flap: an analysis of 30 consecutive reconstructions in maxillofacial surgery.  Ann Plast Surg. 1995;  34 35-42
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• 9 Wolff K D, Grundmann A. The free vastus lateralis flap: an anatomic study with case reports.  Plast Reconstr Surg. 1992;  89 469-475