Necrotising fasciitis is a life-threatening infection that requires radical debridement, usually accompanied by antibiotic therapy and physiologic support. Patients are often left with disabling or disfiguring soft tissue defects. Traditionally, simple reconstructive methods such as skin grafting and local flap coverage have been used to address these defects, due to concerns that free tissue transfer may increase the risk of thrombosis where there has been recent infection and inflammation. We argue that once the infection has been cleared and the patient regains physiological stability, free tissue transfer is a viable reconstructive option that may provide better functional and cosmetic results in selected cases.
A previously healthy 32-year-old male presented with a three-day history of tenderness and spreading erythema of the left arm after a fall. He was septic on admission, requiring transfer to the intensive care unit for inotrope support. Initial examination revealed an erythematous and tender forearm with soft compartments. White cell count on admission was 11 x 109/L with a CRP of 279.
The following morning, he remained septic, requiring ongoing inotropes and with spreading erythema and new skin mottling. He was taken to theatre where necrotic fascia and pus at the medial aspect of the arm extending down the medial intermuscular septum to the neurovascular bundle was noted. Radical surgical debridement was performed and temporary cover achieved with negative pressure wound therapy. Microbiological analysis revealed group A streptococcus and Staphylococcus aureus. Triple intravenous antibiotic therapy was administered in consultation with the infectious diseases team.
Serial debridements and dressing changes were performed on days two, four, eight, 11 and 14 post- admission, leaving a large defect over the volar forearm and medial arm with exposure of the brachial artery, median nerve, ulnar nerve and biceps tendon insertion (Figure 1).
On day 17 post-admission, with a systemically stable patient and serial negative microbiological tests on wound cultures, definitive reconstruction with an ipsilateral anterolateral thigh (ALT) fasciocutaneous free flap and split skin graft was performed (Figure 2). Priority was given to coverage of the neurovascular structures, biceps tendon and elbow flexural crease. The radial artery and venae commitantes were explored under brachoradialis in a freshly dissected plane and confirmed to be suitable recipients under microscopic examination prior to raising the flap. Arterial anastomosis was performed with 9-0 nylon sutures and venous drainage accomplished with anastomoses using venous couplers. All anastomoses were end-to-end. Follow-up one month after reconstruction revealed a movement range of –100 to 1000 at the elbow and 500 to 750 at the wrist (Figure 3).
Discussion and review
Wound closure after necrotising fasciitis is most commonly achieved with skin grafting, local flaps or amputation. Free tissue transfer is less commonly performed. One concern has been the potential for thrombosis due to a systemic inflammatory state with elevated levels of circulating pro-thrombotic mediators that may predispose the affected area to anastomotic occlusion. A hallmark of these necrotising soft tissue infections is thrombosis of the small vessels as a result of endotoxin and inflammatory mediator release, leading to necrosis—seen pathologically as microvascular occlusion, arteritis and intimal thickening.1,2
A number of documented cases report free flap reconstruction following necrotising fasciitis (Table 1). The largest published series reports on 12 successful free flap reconstructions within a population of 224 necrotising fasciitis cases.3 It should be noted that in this series most of the defects were small and the mean number of debridements prior to definitive coverage was 1.1. This contrasts with the experience at our institution where severe soft tissue infections are treated by serial debridement. We consider a clean wound bed and negative microbiology as prerequisites to definitive reconstruction.
The use of a fasciocutaneous free tissue transfer tends to replace what is lost due to necrotising fasciitis. The ALT has proven to be a reliable reconstructive option with minimal donor site morbidity and is the most commonly used donor site. For larger and more central locations, latissimus dorsi musculocutaneous and chimeric free flaps have been used to cover chest and abdominal wall defects.
This case highlights the successful use of free tissue transfer following necrotising fasciitis in order to facilitate coverage of neurovascular structures and bare tendon, while minimising the chance of long-term contracture. While traditional reconstructive options involve skin grafts or amputation, free tissue transfer provides a viable option that may optimise functional and aesthetic results. When performing such procedures we suggest a clinically clean wound with negative tissue culture, a physiologically stable patient where the systemic inflammatory response has been resolved and, wherever possible, anastomoses performed outside of the immediate zone of infection with recipient vessels ideally identified in a virgin plane and examined prior to raising the flap.
Patients/guardians have given informed consent to the publication of images and/or data.
The authors have no conflicts of interest to disclose.
The authors received no financial support for the research, authorship and/or publication of this article.
Revised: May 21, 2018 AEST