One of the most disastrous complications of a trans-tibial amputation, besides death, is gangrene and opportunistic infection, necessitating a transfemoral amputation. This gives not only a higher mortality rate1 but also reduced ambulation rates.2 Wound complications occur in 5% to 22% of lower extremity amputations.1–3 Conversion rates to transfemoral amputation are estimated to be between 9% and 19%.1,3
Maggot debridement therapy (MDT) is an efficacious method to combat severe infection and remove necrotic slough. Its first use in hospitals was in the early 1920s.4 MDT of infected trans-tibial amputation has been described before, but not in a large series.5 In modern surgery, MDT has proven to be a valuable treatment option.6,7 The basic mechanism for the beneficial effects of maggot therapy lies largely in the fact that the maggots have an extracorporeal digestive system. Enzymes such as tryptase, peptidase, and lipase are produced by maggots and released into their environment. Debris and necrotic tissue are broken down, whereas healthy tissue is left unharmed.
Since the first report of vacuum-assisted closure (VAC) therapy in 1997, more than 100 articles on the subject have been published.8 The technique is simple: a subatmospheric pressure is applied to a wound by means of an open-cell foam in the wound connected with a tube to a vacuum source. The fluid is then collected and removed.9 The technique removes interstitial fluid and potential harmful inflammatory mediators.10 Furthermore, it lowers interstitial pressure, thereby promoting the expansion of vessels. There is also a presumed reduction of bacterial load, although the latter is debated.11
From August 2002 to December 2004, five patients with infected transtibial wounds were treated with MDT in our hospital (Table 1). All patients (3 male, 2 female; mean age, 71 years; range, 59 to 85 years) had vascular insufficiency. None of the patients was on dialysis. Two patients were diabetic. Four patients had a severe infection of the transtibial amputation, with visible bone. Two patients were treated while admitted, two while in a nursing home, and one patient was treated ambulatory. All applications were performed in our outpatient department, including our admitted patients. We used two application techniques: the contained technique in which the maggots are placed in a biobag containing an average of 20 maggots, and the free-range technique, in which maggots are placed freely on the wound, covered only by a net. This net is taped to a skin adhesive, which is applied to the periwound skin. This adhesive together with the covering net acts as a barrier to reduce maggot migration. Over the net, wet gauze and a light bandage are wrapped. Patients are well instructed on how to treat the wound at home. Every 3 to 4 days, new maggots are placed on the wound until thorough debridement is reached. The patients do not need to change their gauze at home.
Of the five patients, one was treated with the biobag technique. Eventually, four wounds healed completely; one needed conversion to a transfemoral amputation. Three patients are ambulating now with prostheses.
A 59-year-old man with no relevant medical history was treated for a painful ingrown toenail with a complete nail resection. This was complicated by severe infection of the hallux, unresponsive to antibiotic treatment. A stenosis of the superficial femoral artery was successfully treated with radiological percutaneous transluminal angioplasty. The condition of the patient suddenly deteriorated, necessitating intensive care admission. He needed several laparotomies for a perforation of his colon, necessitating resection of the left colon and the creation of a colostomy. In the same period, a transtibial amputation was performed. The amputation wound deteriorated, with a severe infection unresponsive to antibiotic treatment (Figure 1). We advised the patient to undergo a transfemoral amputation, which the patient refused. He urged us to try maggot debridement therapy. We performed a stump revision, removing the black eschar on removing 1 to 2 cm of the tibia. We started treating the wound with maggots incorporated in a polyvinyl alcohol biobag (Figure 2). In this biobag, the maggots can still act as necrophages. The biobag was placed in the wound, which was subsequently covered with a nylon net and attached to the skin through several adhesive layers to prevent the maggots from escaping and prevent further damage to the skin. The total maggot treatment time was 4 weeks, with two weekly changes. In total, 240 maggots were used. Eventually, the wound closed secondarily, and the patient is now ambulating with a prosthesis.
A 71-year-old man with a history of insulin-dependent diabetes was treated in our hospital for an osteomyelitis of the fourth toe of the left foot. The patient was obese and had a history of hypertension, hypercholesterolemia, and a cerebrovascular accident. Angiography revealed a complete stop of the popliteal artery just proximal to the trifurcation. A femoral-pedal bypass seemed feasible, but the infection progressed and we feared a possible infection of the distal anastomosis. Adequate debridement had to be performed first. The toe was amputated. Despite adequate debridement and appropriate antibiotic therapy, a plantar abscess developed, necessitating a transtibial amputation. Unfortunately, this wound did not heal. There was a wound dehiscence with necrosis and pus, but muscles seemed viable. At this time, MDT was started. The maggots were put freely on the wound, covered only by a net, to prevent the maggots escaping. The patient was treated in the outpatient department. After 1 week of MDT (200 maggots used), the wound was fully clean and VAC was started (Figure 3). VAC was also performed in the outpatient department, and after 2 weeks, the wound (Figure 4) could be secondarily closed. After removal of the stitches, the patient started ambulating and is now ambulating well with a prosthesis.
It is not clear how MDT works. In clinical settings, however, sterile maggots (larvae of Lucilia sericata) can act as necrophages and can destroy bacteria. They appear to be especially useful in the treatment of infected wounds with Gram-positive bacteria.12,13 The larvae can be incorporated in a small polyvinyl alcohol bag. Incorporated in this bag, they still act as necrophages, but there is a less painful sensation on the wound. The maggots are less effective if contained14,15; therefore, the free-range technique is our standard application technique. Every 3 to 4 days, new maggots were placed on the wound until thorough debridement was reached. Although not immediately expected, MDT appears to be an acceptable treatment modality for patients if the patient and family are well instructed.16,17
There are numerous indications for VAC, including complicated surgical wounds, laparostomies, and many chronic wounds.8,18,19 The complication rate of VAC is low; there is a low incidence of localized superficial skin irritation when a portion of the vacuum sponge overlaps the normal skin. This latter complication will not occur if the skin is protected with Duoderm thin (ConvaTec, Woerden, The Netherlands). Lethal complications, such as toxic shock syndrome or anaerobic sepsis, however, have been described.20,21 The number of sponges applied in the wound should be carefully noted in the patient chart.22 Prolonged applications, frequently several weeks, at the expense of early surgical reconstruction, might compromise the outcome in selected cases.23 Contraindications to the VAC are known allergies for any of the components. The use of oral anticoagulation is a relative contraindication.24 Exposed vascular structures are not a contraindication for VAC.25,26
In this article we have described five patients with severe infection of transtibial amputations in which the use of MDT and VAC resulted in fewer conversions to transfemoral amputation, with positive effects on mortality and morbidity.
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