higher than 180 mg/dL. In patients with or without diabetes, perioperative hyperglycemia (>180 mg/dL) carries a significantly increased risk of postoperative wound infection.1 The hemoglobin A1C is a blood test used to assess the long-term control of blood glucose. Because hemoglobin molecules remain in the blood for 3 months, it is possible to gauge glucose control over a 120-day period (not 180 days) by measuring glycosylated hemoglobin levels. A normal hemoglobin A1C is around 6%. Tight blood glucose control with intensive insulin therapy and normoglycemia (<110 mg/dL) has shown a reduction in hospital deaths in some trials.2 However, where glucose control is <7 mg/dL, there is an increased risk of death in critically ill patients.3 Although postoperative hyperglycemia and undiagnosed diabetes increase the risk of surgical site infections, elevated hemoglobin A1C does not linearly correlate.4,5
Albumin can provide a useful indication of nutrition. Its half-life is 20 days, and a normal value is 3.6–5.4 g/dL. A value of 2.8–3.5 g/dL suggests mild malnutrition, 2.1–2.7 g/dL suggests moderate malnutrition, and less than 2.1 g/ dL indicates severe malnutrition. A large study published in 1999 involving more than 50,000 patients showed that as preoperative albumin levels decreased, early postoperative mortality and morbidity increased exponentially.1 The authors concluded that albumin was a useful predictor of outcome in major surgical procedures. Prealbumin, rather than albumin, has a half-life of 3 days and can be assessed by the rule of fives. A normal value is greater than 15 mg/dL, mild deficiency is less than 15 mg/dL, moderate is less than 10 mg/dL, and severe is less than 5 mg/dL. Prealbumin, also known as transthyretin, is a transport protein for thyroxine and is actually unrelated to albumin. It earned its name because it runs faster than albumin on gel electrophoresis. Although prealbumin levels can be a useful marker of nutritional status, they are less reliable during infective or inflammatory processes as prealbumin is an acute phase protein.
A systemic review of imaging in the lower limb confirmed that peripheral arterial disease is best imaged using magnetic resonance angiography (MRA) because this has an overall better diagnostic accuracy than computerized tomography angiography (CTA) or ultrasonography. It also showed patients’ preference of MRA over standard contrast angiography.1 MRA uses magnetic fields to evaluate blood vessels. It requires no radiation dose (in contrast to CTA) and can be performed with or without intravenous (IV) delivered contrast (normally gadolinium). This has a lower risk of contrast reaction in terms of anaphylaxis or renal injury compared with the iodine-based contrasts generally used for computed tomography (CT). MRI will visualize the surrounding soft tissues more effectively than CT, but is generally less useful for bony imaging. In the trauma setting, patients with long bone fractures such as this patient, with metal hardware (external fixation devices, internal plates, or intramedullary nails), may not be able to have MRI if the hardware is not MRI compatible. In such circumstances, CT or plain film angiography may be required as an alternative. Plain film radiography is more invasive than CT or MRA because it involves cannulation of the arterial tree, usually from the groin. Dye is then injected directly into the arterial system. Plain radiographic films can demonstrate calcification of vessels and may be useful for assessment of fractures, foreign bodies, and osteomyelitis, rather than vascular imaging. In spite of the usefulness of imaging, clinical examination with palpation of distal pulses and the use of handheld Doppler machines can provide accurate assessment of limb vessels and are still preferred by many surgeons as the primary modality for assessment. Maintaining skills in this assessment is vital for plastic and reconstructive surgeons.
The ankle-brachial pressure index is a noninvasive test used to investigate the lower limb vasculature. It compares a patient’s lower limb arterial pressure with that of the upper limb and expresses it as a ratio. A normal ankle- brachial pressure index is between 0.9 and 1.2. A value greater than 1.2 suggests calcification as vessels become noncompressible. A value of 0.5–0.9 is associated with mixed arteriovenous disease. A value of less than 0.5 suggests critical arterial stenosis, and a value of less than 0.2 indicates that ischemic gangrene is likely. The clinical picture is consistent with the appearance of an arterial ischemic ulcer, and referral for a vascular opinion is recommended. TISSUE RECONSTRUCTION AND WOUND CLOSURE 5. What was the main limitation of the original reconstructive ladder concept? D. The reconstructive process was performed in a stepwise manner. The reconstructive ladder was a concept described by Mathes and Nahai1 to categorize options for wound closure, progressing in a stepwise manner of complexity from healing by secondary intention to free tissue transfer, with the simplest option being preferentially used first. The major conceptual understanding of the original concept was that each rung was mandatory to climb before hitting the next rung. This was corrected by Gottlieb and Krieger2 who coined the term “reconstructive elevator,” which they described in the Editorial section of Plastic Reconstructive Surgery in 1994 to emphasize that reconstruction is flexible and does not have to proceed in a stepwise fashion. Reconstruction should immediately proceed to the best option in any given scenario, taking into consideration the patient, the wound, and the resources available. The original reconstructive ladder did not include negative pressure dressings or dermal matrices; however, this was not its major caveat. Janis et al3 refined the reconstructive ladder to include dermal matrices and negative pressure wound therapy. Other models for reconstruction have included the reconstructive triangle1 and the reconstructive matrix.4 The reconstructive triangle includes tissue expansion, local flaps, and free tissue transfer. The reconstructive matrix contains three axes representing technological sophistication, surgical complexity, and patient’s surgical risk (see Figs. 2.1 and 2.2, Essentials of Plastic Surgery, third edition).
5. Latham R, Lancaster AD, Covington JF, Pirolo JS, Thomas CS Jr. The association of diabetes and glucose control with surgical-site infections among cardiothoracic surgery patients. Infect Control Hosp Epidemiol 2001;22(10):607–612
Negative pressure wound therapy is commonly used to accelerate wound healing either as a sole means of wound closure or to prepare a wound for skin grafting. Argenta and Morykwas1 first described the term in 1997 after their clinical experience. It is believed to cause deformation of cells that leads to an increase in their mitotic activity. Fluid exudate is removed during negative pressure therapy, but the production of fluid per se is not affected. Production of granulation tissue is increased. Use of negative pressure therapy should be avoided in wounds with exposed vessels, fistulas, active infection, or malignancy. It can safely be used after wound debridement providing that hemostasis is adequate and the points described above are addressed with respect to the other contraindications.
Traditional approaches to surgical debridement are based on clinical examination of the wound to assess for nonviable and viable tissues with the intention to surgically remove all nonviable tissues, while preserving all viable tissues. In general, sharp debridement is performed progressively with a scalpel, scissors, curette, or high- powered water jet stream (hydrosurgery) until bleeding healthy tissues are visualized in the wound bed. With clinical experience, this can be performed accurately and consistently to a high level. However, in order to help accuracy of debridement, a technique of using methylene blue dye has been described as a particularly useful adjunct. Using this approach, methylene blue dye is applied to the wound bed and the peripheral wound edges are also marked. The wound edges are sharply refreshed, and the wound base is debrided such that all of the blue stained tissues are removed. Once the blue stained tissues have been removed, there should remain only healthy tissues. Further assessment of this can be via a colorimetric approach where three colors will signify healthy tissue: Red (muscle), white (fascia and paratenon), and yellow (fat, bone). Other colors such as gray, green, purple, or black are not normally found in healthy wound beds and should be further debrided.1 Quantitative tissue cultures are considered by some to be an important adjunct to wound debridement, especially where there is or there has been a prosthesis or chronic wound. For example, in cases of orthopedic metalwork infection and associated osteomyelitis, multiple tissue samples of bone and soft tissue can be sent for culture before and after wound debridement to assess infection status and obtain microbiologic characterization. However, this will not provide on-table results to guide debridement. Most microbiological testing requires at least 36 hours to process. Furthermore, there may be difficulties in ensuring accuracy, which is affected by many factors.2 Frozen section biopsy is another useful assessment tool for characterizing tissue and is most commonly performed to assess for tumor presence. Key diagnostic indications are to prove or disprove malignancy and confirm a tissue diagnosis. Frozen section biopsy is also strongly indicated to assess for tumor clearance at the margin where larger, more complex tumors have been resected. In principle, it is possible to have frozen section to assess tissue normality and viability, but in reality, it is not used in this form.3 Iodine solution is commonly used as a skin preparation for its microbial effects and so is important in surgical wound preparation, but it is not specifically helpful to guide the surgical debridement process per se. Indocyanine green (ICG) dye is generally indicated for use in plastic surgery to assess flap perfusion intraoperatively, for example, when planning and executing a perforator flap design. It forms part of an angiographic imaging modality. Intravenous ICG is delivered so that tissue perfusion can be assessed using dynamic laser fluorescence videography. It uses a digital video camera system and a near-infrared light. It has been used to help assess wounds following trauma and burns so it may have a role in cases such as that described in future practice. However, it may be best used to plan surgery prior to reaching the operating room and at present still remains more experimental than in mainstream use.4
Osteoradionecrosis (ORN) is a condition where bone death occurs secondary to radiation and is most commonly seen in the mandible following treatment of head and neck cancers. Symptoms of ORN can be severe with significant impact on patients’ quality of life. Key problems include chronic pain, nonhealing wounds, limited mouth opening, and mouth ulcers. It is related to high doses of radiation and occurs because of the damaging effects of radiation on tissue vascularity. The condition is difficult to treat and the main approaches include hyperbaric oxygen therapy and surgery to remove the affected bone. Hyperbaric oxygen therapy involves breathing pure oxygen in a pressurized room. It is used for many conditions ranging from decompression sickness, carbon monoxide poisoning, infections, and wound healing problems. Patients are positioned in a chamber either individually or with other patients and the air pressure in the chamber is increased to three times the normal air pressure at sea level, providing supranormal levels of oxygen. There is a substantial research evidence base to support its use, but not all centers will have access to this treatment modality. For ORN, patients will need multiple episodes in the hyperbaric chamber.1 Transcutaneous oxygen tension (TcPO2) is a measure (not a treatment) of a response to oxygen administration as a surrogate marker for reversible ischemia. Normal levels are 400 mm Hg or greater. It has been used to provide a measure of lower limb peripheral vascular insufficiency. Stem cell therapy has a number of potential uses in plastic and reconstructive surgery including the potential for regeneration of skin, cartilage, and bone. However, its use in general wound healing presently lacks high level evidence. There have been small studies evaluating the effects of stem cells in ORN as well as animal models in rats, which may, in future, provide some benefit for ORN patients.2 Platelet-rich plasma contains high concentrations of growth factors and is used in a number of situations including sports medicine, orthopedics, general surgery, dermatology, and plastic surgery. It is thought to help in wound healing and have beneficial effects on skin quality as a rejuvenation procedure. It may also help male pattern baldness. However, its use still lacks high level evidence in terms of precise usage and outcomes. One study assessed the benefits of platelet-rich plasma in prevention of ORN, but failed to show any significant benefit.3 A diagnosis of ORN is made on clinical grounds with the exposure of necrotic bone (sequestra) with ulceration of the skin and/or mucous membranes in the absence of evidence of tumor recurrence. In a patient with a clinical diagnosis of ORN, although tissue biopsies and cultures can be helpful to exclude tumor, to prove evidence of necrosis, and provide information on infection, they would not specifically help treat the condition.
A number of biologic skin substitutes are available. They can be classified according to composition: human derived, animal derived, synthetic, or a combination of these. All of the products listed contain animal derivatives, with the exception of AlloDerm (LifeCell, Branchburg, NJ). This is a regenerative tissue matrix derived from cadaveric human dermis. It has been used successfully in burn patients to reduce joint contracture.1 It has also been used in breast and abdominal wall reconstruction. Biobrane (Smith and Nephew, London) is a biologic skin substitute comprising of silicone, nylon, and porcine collagen. It is used in the acute setting for management of partial-thickness burns, especially in children. It can accelerate healing, decrease pain, and reduce dressing changes. ACell line of products (Columbia, MD) are comprised of porcine urinary bladder matrix and are available in powder and sheet formations. They are intended for use in burn wounds, and pressure and venous ulcers. Integra is a bilayer of outer silicone combined with inner bovine collagen and glygosaminoglycans. It is used in burn surgery in both the acute and elective settings. SurgiMend (Integra LifeSciences, Plainsboro, NJ) is a bovine-derived acellular dermal matrix and is used in abdominal wall reconstruction. (See question 8 answer and Chapter 9, Essentials of Plastic Surgery, third edition.)
Apligraf (Organogenesis Canton, MA) is a bioengineered skin substitute marketed for use in diabetic foot and venous leg ulcers. It has FDA approval for use in both of these conditions. It comprises a bilayer of bovine collagen and human foreskin-derived fibroblast matrix under human foreskin-derived keratinocytes. It therefore provides both cells and matrix for the nonhealing wound.1 Matriderm (Medskin Solutions, DR, Suwelack AG, Billerbeck, Germany) is a dermal matrix with bovine dermal collagen (Types I, III, and IV), elastin, and silicone sheeting. It is used beneath split skin grafts to provide a thicker soft tissue cover with the intention of providing superior cosmetic results than split skin graft alone. ReCell (Avita Medical, Cambridge, UK) is an autologous noncultured cell therapy delivered as a cellular suspension. It is marketed for use in acute thermal burn injury and involves harvesting cells from the patient intraoperatively (as a very small split skin graft) which can then be sprayed as a suspension onto the burn injury following chemical and mechanical breakdown. The spray is then applied instead of using a split-thickness skin graft. A proposed benefit of ReCell is the very significantly reduced donor site, which in one trial was reduced by 40 times.2 Acelagraft (Celgene Cellular Therapeutics, Cedar Knolls, NJ) is a decellularized, dehydrated, frozen human amniotic membrane product that is marketed for use in wounds including the corneal and conjunctival surfaces of the globe. Epicel (Genzyme Biosurgery, Cambridge, MA) is a cultured epidermal autograft derived from the patients’ own skin. It is intended for use in management of deep dermal or full-thickness burns and has FDA approval for this. Epicel grafts are made by harvesting skin cells from a patient and growing them in an incubator on mouse cells. The skin sample is typically the size of a postage stamp. The finished grafts are used to provide skin cover either with split skin grafts or instead of them. Epicel grafts can be grown in a relatively short time frame with 100% of total body surface area (TBSA) in less than 4 weeks.