Unusual case of a free anterolateral thigh flap partial necrosis in a COVID-19 positive young male following extremity reconstruction

Abstract

Free flap procedure provides an overall success rate of 97%, which decreases to 85% in hypercoagulable states. COVID-19, as a pro-thrombotic disorder, therefore seems detrimental to free flap survival. We encountered a case of unique pattern of free flap partial failure in a young male who underwent extremity reconstruction. The patient was diagnosed as COVID-19 positive on the 3rd day post-reconstruction. The flap survived well for the first 7 days post-operatively, but gradually the skin got necrosed and the subcutaneous fat layer was preserved when debriding. To our knowledge, this is the only case in which the skin of the free flap of a COVID-19 positive patient was necrosed almost entirely subsequently, while the subcutaneous fat was relatively preserved.

Introduction

COVID-19 has been associated with both macrovascular¹ and capillary² thrombus formation leading to organ failure. This implies that COVID-19 might be an independent risk factor for free flap failure. However, after an extensive literature search, we could find only one article reporting on free flap failure in a head and neck reconstruction for a COVID-19 positive patient.³ We encountered an unique case of partial free flap failure a few days after extremity reconstruction in a young male who tested positive for COVID-19 and had no other co-morbidities.

Case report

A 16-year-old male patient presented with post-traumatic right-side foot and ankle defect with exposure of extensor tendons and ankle joint. After necessary evaluation and planning, we performed debridement of the defect (Fig. 1) and reconstruction with a free anterolateral thigh perforator flap (harvested from the right thigh). Donor artery and vein was anastomosed with recipient-site anterior tibial artery and vein respectively, in an end-to-end anastomosis. The patient was started on low-molecular weight heparin post-operatively. The flap survived well after an uneventful surgery.

Fig. 1.

Defect of dorsum of the right foot and ankle following debridement.

On the 3rd post-operative day, the patient developed a high fever (Fig. 2). The nasopharyngeal swab polymerase chain reaction test for COVID-19 was positive (cycle threshold value was 18), and then he was sent to isolation and treated as per the existing guidelines for COVID-19. The chest X-ray findings, blood counts, ferritin levels, prothrombin time, and international normalised ratio values were normal, while D-dimer value had raised 6-fold (3.1 mg/L). The flap was healthy for the first 7 days, however on the 8th post-operative day congestion started appearing over the distal flap, and surface scratch was bleeding slowly and darkly. After exploration, there was no thrombosis in both vessels, and the anastomotic function was normal. D-dimer value fell to 2.5 mg/L. But mild patchy discoloration of the flap started developing on the 13th post-operative day (Fig. 3). Flap started becoming edematous. Exsanguination of the flap for decongestion was done. Gradually, the entire skin became dark and there was no bleeding on dermal scratching (Fig. 4), while on deep puncturing there was very slow bleeding on the 21st post-operative days. On re-exploration, it was observed that only the skin was necrosed and deep layer of fat had healthy bleeding. Therefore, tangential excision was performed, in which only the dermis and superficial layer of fat in some areas were removed (Fig. 5). As there was no exposure of bone or other vital structures, negative pressure wound therapy was given for 10 days. After removing vacuum assisted closure devise, the defect was covered with split thickness graft harvested from the right thigh (Fig. 6, Fig. 7). Finally, the patient healed uneventfully.

Fig. 2.

Healthy free anterolateral thigh flap on the 3rd post-operative day.

Fig. 3.

Patchy necrosis of skin of the free anterolateral thigh flap with dark and slow bleeding on surface scratch.

Fig. 4.

Complete necrosis of the skin of the free flap.

Fig. 5.

Bright bleeding from deep fat layer of the flap following tangential excision of the skin, with take-up of some part of the skin along the proximal and medial border.

Fig. 6.

Healthy granulations over the fat layer following negative pressure wound therapy.

Fig. 7.

Skin grafting over the granulating fat layer of the free flap.

Discussion

Benmoussa et al.³ were the first one to report a case of free fibula flap and thoracodorsal artery perforator flap failure after 7 days post-operatively. The reconstruction was done in head and neck oncology surgery for a 56-year-old female patient with COVID-19. Based on their observation, they recommended using heparin in such cases for at least 15 days and performing pathological analysis for all patients with flap failure for up to 6 months. In a reply to this article, Al-Benna et al.⁴ suggested that pre-existing endothelial dysfunction is a common underlying condition among people with an increased risk of severe COVID-19 and free flap failure. The author recommended the use of heparin prophylaxis due to its anticoagulant and anti-inflammatory functions. Inouye et al.⁵ reported 2 cases of head and neck reconstruction using free tissue transfer with severe infection at the donor and recipient sites after post-operative infection of COVID-19. Other than that, it was a successful procedure. Eventually the flaps survived in both cases.

Our case with subsequent mild infection of COVID-19 after the successful survival of the free flap for 7 days, only the skin was lost and the subcutaneous fatty tissue was preserved. This implies that only microvasculature was compromised, and no flow across the anastomosis of donor and recipient vessels was found. The patient had no co-morbidity such as obesity, hypertension, diabetes, cardiovascular disease, cancer or aging, which could increase the risk of endothelial dysfunction. Prophylactic heparin was also started even before the diagnosis of COVID-19 and continued for 21 days. Therefore, it seems that COVID-19 itself is an independent risk factor for the partial free flap failure, although this warrants further exploration.

There were certain limitations. We were unable to send the debrided skin tissue for histo-pathological analysis. And with only one case, association between partial or complete free flap failure and COVID-19 infection could not be calculated.

After 7 days of uneventful survival of the flap, only the skin was necrosed but the subcutaneous fat was preserved. There is no any other similar reference to this unique pattern of free flap partial failure in a subsequent COVID-19 positive patient. We recommend exploring further to determine whether microvasculature is more affected than macrovasculature in COVID-19 patients.

Funding

Nil.

Ethical statement

Informed consent was obtained from the patient included in the study. There is no information (names, initials, hospital identification numbers, or photographs) in the submitted manuscript that can be used to identify patients. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008.

Declaration of competing interest

There is no conflict of interest.

Author contributions

All the authors had contributed in collecting data, preparing and proofreading the manuscript.