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Acs0627 Lower Extremity Ulcers


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Acs0627 Lower Extremity Ulcers

  1. 1. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 1 27 LOWER-EXTREMITY ULCERS Robert D. Galiano, M.D. A lower-extremity ulcer presents a unique window into a patient’s conditions, the involvement of a lower-extremity surgeon is crucial health. The term ulcer implies a nonhealing wound, meaning that for ensuring that a patient is offered a comprehensive set of man- an ulcer is most likely to be present in a patient with an underlying agement options. One potential obstacle to such involvement, pathophysiologic derangement. Accordingly, the surgeon treating a however, is that most surgeons complete their surgical residencies leg wound is obliged to address any impediments to healing that and fellowships without a thorough grounding in wound care. exist, whether local or systemic, with a well-designed therapeutic Many, in fact, are still unaware of any dressings other than wet-to- plan. Although there are literally scores of different types of lower- dry dressings. Today, routine management of leg wounds is often extremity ulcer [see Table 1], it is neither practical nor necessary for left to nurses, physical therapists, and other nonsurgical specialists. the surgeon to learn a specific treatment for every single type. In Although these practitioners are certainly capable of treating most cases, it is better to develop a logical framework that empha- patients with uncomplicated lower-extremity ulcers, it is important sizes the common features shared by most leg ulcers (rather than to recall that an understanding of how the body heals in response the differences). Such a focus on the shared causal factors of lower- to injury lies at the heart of all surgical care. It is time that surgeons extremity ulcers, coupled with a knowledge of modern wound care reengaged themselves in the management of wounds, particularly and an appreciation of the unique anatomy of the leg and foot, will lower-extremity wounds: surgery is the discipline that is best suit- facilitate patient understanding, enhance communication between ed, by both training and inclination, to assume the care of these consultants and primary care physicians, and, most important, complex, challenging, and often frustrating problems. There is enable efficacious patient care. much room for improvement in this rapidly evolving field, and the The following characteristics are common to most lower- intellectual and professional rewards to be gained from increased extremity ulcers.1,2 integration of surgeons into the care of patients with leg wounds are enormous. 1. Ischemia. Several factors, including peripheral arterial disease The goal of modern leg wound care should be expeditious clo- and edema, contribute to the prevalence of tissue ischemia in sure and long-term durable coverage, followed by carefully tailored the lower extremity. Ischemia may be local or regional, or it may preventive measures. Unfortunately, prevention is relatively be dependent, associated with episodic ischemia-reperfusion neglected in this discipline. For example, a patient with a diabetic injury. Cells require oxygen to carry out basic metabolic func- foot ulcer may require an Achilles tendon–lengthening procedure tions, fight infections, and heal wounds.3-5 Edema contributes to deal with the ankle equinus and the resulting tendinous to tissue hypoxia by increasing the distance between a cell and derangements that shift the weightbearing pressures to the area the nearest capillary.6 under the metatarsal heads. A program of offloading and local 2. Age. Most leg ulcers occur in elderly persons. Many comorbid wound care may heal the ulcer, but recurrence is predictable, often conditions (e.g., diabetes, venous stasis, and peripheral arterial even with the best orthotics, unless the stiff, foreshortened tendon disease) are age dependent, and aged cells lose much of their is lengthened and gait biomechanics are restored.The high risk of ability to respond to sublethal ischemia.7-9 Consequently, a recurrence—and the easiness of the operation that prevents it— given degree of ischemia typically has a greater impact on an will not be appreciated by a clinician who is not familiar with elderly person than on a young one. lower-extremity surgery. Many wounds can be healed by means of 3. The presence of bacteria. Most chronic ulcers are colonized by offloading and dressing changes, but it is probable that in the bacteria in the form of a biofilm, which is difficult to treat and future, best-practice management of these lesions will include perpetuates the inflammatory response within a wound.10 interventions aimed at minimizing ulcer recidivism, often by Although the adverse effects of bacteria on wound healing have addressing any anatomic derangements that may have given rise to long been noted, those of biofilm, which does not always give the ulcer in the first place. rise to an overt phenotype or infectious picture, have been Before surgical measures or advanced dressings are even con- underappreciated. Indeed, a stalled, nonhealing wound is one sidered, much can be done to enhance the healing potential of a of the more common presentations of biofilm. Many of the cur- lower-extremity ulcer.2,11-13 The main goal of any intervention rent advances in wound care practice and dressing use focus on should be to ensure that oxygen and nutrients are reaching the management of the bioburden borne by the wound. cells within the wound. For most wounds, the most important Acknowledging and addressing each of these common factors will steps toward this goal are offloading and control of edema. With allow the surgeon to heal the vast majority of leg ulcers, either sur- good wound care, appropriate antibiotic therapy (when indicated), gically or nonsurgically; ignorance of these factors will result in a and complete bed rest, even a large ulcer may heal without further haphazard approach to leg ulcer care that will inevitably be associ- treatment. Indeed, it is the dependent position of the lower extrem- ated with inferior outcomes. ity and the absolute requirement of most patients to ambulate that Wound care practitioners may come from any of several medical indirectly accounts for failed ulcer healing in many cases. If the specialties. In my view, however, lower-extremity ulcers are best dependent position can be changed and the patient can elevate the treated when the expertise and know-how of an interested surgeon leg, the edema will be diminished and local tissue perfusion will be are closely integrated into patient care. Given that the majority of improved. Another step that is often neglected is ensuring ade- problem leg wounds occur in patients with significant comorbid quate hydration, particularly in patients who are hospitalized or
  2. 2. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 2 Table 1 Types and Causes lessly prolonged courses of therapy, it may be used to deny of Lower-Extremity Ulcers advanced treatments to patients, and it fails to take into account the dynamic nature of wound healing, whereby wounds may improve, stall, and then improve again. Venous Arterial A better definition of a chronic wound is one that has fallen off Mixed the trajectory of expected healing.14 This newer definition has Vascular malformations implications for clinical practice, in that it emphasizes the impor- Vascular Lymphatic tance of measuring the wound periodically.The wound should be Primary lymphedema measurably smaller during each office visit: typically, an actively Secondary lymphedema healing wound should show a reduction in area or volume of Pyoderma gangrenosum approximately 10% per week.15 If the wound is healing at a lesser Systemic lupus erythematosus rate or is scarcely healing at all, an immediate effort should be Rheumatoid arthritis made to investigate the reason for the delay. There is no time for Vasculitic Wegener granulomatosis complacency (e.g., “Let’s see how it’s doing next month”), Scleroderma because the stalled wound is symptomatic of a significant under- Polyarteritis nodosa lying problem. It is imperative for the surgeon to consider possible Diabetic neuropathic ulcer causes—for example, infection or bacterial colonization. Often, an Neuropathic office debridement is necessary at this stage to reduce the accu- Peripheral neuropathy, with or without ischemia mulation of tenacious biofilm. If the wound shows no evidence of Frostbite healing despite vigilant wound care, a biopsy should be consid- Burns ered, particularly if the wound has been present for more than 3 Traumatic Factitious months. Other potential diagnoses besides malignancy should be Injury considered as well, including vasculitis, pyoderma gangrenosum, Acute and fungal or mycobacterial infection. Radiation-induced Chronic A number of clinical trials have shown that the rate of healing in Sickle cell ulcers the first 30 days after the initiation of good wound care is strongly Polycythemia vera predictive of an ulcer’s ultimate fate, especially in the case of dia- Hematologic/dyscrasias Thalassemia betic and venous stasis ulcers: the lesions that eventually heal are Thrombocythemia the ones that show the highest initial healing rates.16-20 This obser- vation, though perhaps intuitively obvious, is not always appreciat- Basal cell carcinoma Squamous cell carcinoma (Marjolin ulcer) ed, nor are its lessons always correctly applied. Part of the problem Malignancies Malignant melanoma is that many ulcers are not evaluated frequently enough in the out- patient setting. Weekly measurement is essential for evaluation of Cutaneous tuberculosis healing potential. In fact, it is likely that in the future, the bench- Syphilis mark measured by patients, peers, and insurance companies to Tropical ulcers Parasitic infections evaluate a wound care practitioner’s success will be time to ulcer Fungal infections healing. If an ulcer eventually heals after 9 months, this is still a suc- Sarcoidosis cess in some ways, but one may reasonably wonder whether the time away from work, the cost of dressings, and the multiple office visits might have been substantially reduced if the wound care have recently undergone surgery. Hydration enhances preload and practitioner had more frequently evaluated the rate of healing, had ensures that arteriovenous shunting does not occur to divert blood aggressively and preemptively rethought his or her approach, and away from the cutaneous tissues. Control of pain is also important perhaps had resorted to different therapeutic measures. to minimize sympathetic-induced vasoconstriction. Smoking ces- Instead of thinking in terms of acute wounds versus chronic sation is beneficial: smoking impairs vascular flow, reduces vasodi- wounds, as has been traditional, it may be more useful to think in latation, and accelerates the formation of atherosclerotic disease in terms of uncomplicated wounds versus problem wounds.2 The vessels. Counseling should therefore be offered to all patients who use tobacco.The extremity should be kept warm so as to open up capillary beds and enhance tissue perfusion. Supplemental oxygen may be helpful for patients with a regional or systemic malperfu- Table 2—Conditions That Interfere with Healing sion state. Immunosuppressive medications Transplant patients Arthritic patients Chronic Wounds and Problem Wounds Autoimmune diseases As discussed elsewhere [see 1:7 AcuteWound Care], wounds nor- Steroid use, including inhalers mally progress through several temporally overlapping phases of Recent major surgery healing. A chronic wound, however, does not progress through all Smoking of these phases but is arrested in one of them, usually the inflam- Malnutrition (particularly acute malnourishment or a recent catabolic state) matory phase. For practical purposes, a chronic wound can be Infection defined—and, until comparatively recently, generally has been Age defined—in strictly temporal terms, as a wound that has not Diminished tissue perfusion healed after 3 months.This once-standard definition is now being Radiation reconsidered, on the grounds that it may subject patients to need-
  3. 3. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 3 category of problem wounds encompasses not only chronic and the limitations and compromises attendant on this evolution wounds but also wounds occurring in persons whose comorbid are evident in the predisposition of the legs and feet to ulcerate. conditions will almost certainly result in a protracted course of The characteristics of the skin of the lower extremity play a role healing. Such persons include most elderly and hospitalized in ulceration. The skin in this area is taut, with minimal intrinsic patients, but there are numerous other conditions besides laxity, and this tautness has implications for flap design.24 Foot skin advanced age and hospitalization that can impair healing [see Table is extremely thick, and calluses form readily in response to pres- 2]. For example, a week-old Wagner stage 2 ulcer in a diabetic sure. Unfortunately, excess callus formation can exacerbate pres- patient is a problem wound and should be treated promptly and sure in the sole of a diabetic person’s foot. Obesity and lymphede- comprehensively with offloading, moist wound care, and frequent ma can alter the barrier function of the skin, as well as diminish cel- inspections. A dehiscence at a saphenous vein harvest site in a lular perfusion25; lymphedema is particularly damaging, in that the patient who underwent a cardiac bypass is also a problem wound, accumulation of fluid in the interstitial space causes a relative both because of the swelling typically present and because of the hypoxia coupled to altered macrophage function in conjunction likelihood of bacterial colonization in the relatively hypovascular with the induction of a chronic inflammatory state and tissue fibro- subcutaneous tissue of the thigh. The mode of injury also plays a sis.26 Contact sensitivities are common and may influence compli- role in determining whether a wound is a problem wound; for ance with the wearing of dressings and compression garments. example, a heavily devitalized wound in an 18-year-old patient will Lipodermatosclerosis may develop as the result of chronic extrava- heal as poorly as a chronic wound if it is not adequately debrided sation of red blood cells into the skin and deposition of hemo- and wound perfusion is not ensured. By preemptively addressing siderin within macrophages. Either hypo- or hyperpigmentation potential impediments to healing, the surgeon can minimize com- may occur, along with the characteristic “woody” firmness of sub- plications, shorten the time to healing, and help the patient return cutaneous fibrosis.27-29 Venous eczema is common in patients with to work in an expeditious fashion. venous ulcers; it is probably an inflammatory process and can gen- erally be distinguished from cellulitis on the basis of its chronicity, its poorly demarcated borders, and its pruritic, scaly nature. Incidence and Epidemiology The tendons also play a significant role in the etiology of dia- It is estimated that at any point, the incidence of lower-extrem- betic forefoot ulcers, and their functional relations must be ity ulcers in the United States may be as high as 1%.21 The actual addressed when an amputation is to be performed. Dysregulation number of afflicted patients will rise as a consequence of the exten- of the tendons is a frequent finding in limb ulcer patients. Chronic sion of the expected average lifespan, the proportional increase in hyperglycemia leads to glycosylation of collagen, with subsequent atherosclerotic vascular disease, and the growing epidemic of obe- loss of elasticity in connective tissues, including muscle, tendons, sity and associated diabetes mellitus. and skin; an example is glycosylation of the Achilles tendon, which The transition of baby boomers from middle age to the ranks of destroys its flexibility and prevents adequate dorsiflexion during the elderly (over the age of 65) is already occurring, and it is esti- normal gait. The forefoot then bears the brunt of the person’s mated that by 2030, the elderly will constitute 20% of the U.S. weight during walking, and the accumulated stress, particularly in population.22 Persons older than 85 years constitute the most the setting of underlying neuropathy, culminates in a stereotypical rapidly growing segment of the population. As noted (see above), diabetic forefoot ulcer (the so-called mal perforant ulcer). Correc- by far the greatest number of ulcers occur in the elderly, both tion of underlying biomechanical abnormalities and treatment of because of the increased incidence of atherosclerosis and because underlying medical conditions are as important to the overall treat- of the parallel increase in venous stasis disease. ment plan as debridement and wound care are. In parallel with the increase in the elderly population, there is The cutaneous innervation of the leg skin must also be taken also a substantial increase in the diabetic population. The United into account. The nerves to the lower extremity include the com- States is witnessing (and leading) the dual global epidemics of dia- mon peroneal nerve, the superficial peroneal nerve, the deep betes and obesity.There are nearly 21 million people with diabetes peroneal nerve, the sural nerve, the saphenous nerve, and the tib- in the United States, 6 million of whom are unaware that they have ial nerve. The branches in the foot are the medial plantar nerve, the disease.23 Approximately 15% of these 21 million are at signif- the lateral plantar nerve, and the calcaneal branch.The foot is pre- icant risk for the development of a foot ulcer. Indeed, 60% of disposed to neuropathy for unknown reasons, one of which is lower-extremity amputations unrelated to trauma are performed in almost certainly local-regional ischemia. This predisposition is diabetic patients.23 Most of these amputations are preventable.The particularly relevant to the pathogenesis of diabetic neuropathic continuing increases in the incidence of atherosclerotic disease, foot ulcers; chronic tissue hyperglycosylation and fibrosis probably diabetes, and venous stasis disease make it essential for surgeons to play roles as well. The medial and lateral plantar nerves travel improve their awareness of and competence in the management of through the tarsal tunnel, a tight anatomic space just under the wounds in the lower extremity. flexor retinaculum. Division and release of the retinaculum serves a purpose analogous to that served by carpal tunnel release in the hand. In diabetic patients with forefoot ulcers, this procedure can Anatomic Considerations reduce ulceration. Although tarsal tunnel release evolved as a Several unique anatomic and functional factors predispose the means of treating neuropathic foot pain, it has been shown, in lower extremity to ulceration. These factors include the relentless properly selected patients, to prevent foot ulceration by restoring effects of gravity and the repetitive trauma of ambulation. Another foot sensibility.30 factor is the formidable challenges involved in transporting blood A solid grasp of the structural anatomy of the lower-extremity from the heart to the foot and back.The vascular tree of the foot is vasculature is, of course, essential for surgeons treating patients a terminal capillary bed, like that in many other organs, but it is with leg ulcers. Perhaps even more important, however, is an exposed to an enormous pressure gradient that is not present in understanding of precisely how the various blood vessels are relat- other parts of the body. In humans, the lower extremities evolved ed to one another, as well as to the specific structures and areas differently from the upper extremities (to enable a bipedal gait), that they supply. Such an understanding may be facilitated by
  4. 4. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 4 Table 3 Angiosomes (Vascular Territories) of Foot that call for emergency triage in the operating room. One such sur- gical emergency is a leg or foot wound that is also acutely ischemic. The priority in this situation is prompt revascularization of the leg. Artery Vascular Territory Supplied Another emergency is a gangrenous leg or foot wound that has over- come host resistance and is associated with ascending sepsis (often, Anterior tibial artery Anterior aspect of lower leg, anterior ankle necrotizing fasciitis).The priority in this situation is urgent debride- Dorsalis pedis artery Dorsum of foot ment of the devitalized and infected tissues; in some cases, emer- gency guillotine amputation may be required. All other wounds are Peroneal artery Posterolateral aspect of lower leg not emergencies and may be evaluated in a more systematic fashion. Anterior perforating branch Upper portion of lateral ankle Calcaneal branch Lateral plantar heel Each patient encounter should commence with a vascular examination. Diligent evaluation of the blood supply to the lower Posterior tibial artery Posteromedial aspect of lower leg Calcaneal branch Medial heel Lateral plantar artery Lateral aspect of plantar foot, plantar forefoot (usually extends to hallux) Medial plantar artery Medial instep region between heel and forefoot viewing the blood supply to the foot and lower leg through the con- cept of angiosomes—that is, the specific vascular beds supplied by Figure 1 Shown are the angio- major named arteries. Angiosomes have been well described by somes of the anterior tibial artery and the dorsalis pedis artery. Taylor,31 and their application to the foot has been advanced by Attinger and associates.32,33 The significance of the angiosome con- cept (which is frequently employed by plastic surgeons but is less familiar to other surgeons) lies in its ability to relate the major nutritive blood vessels to the surface anatomy, to the physical examination, and to the planning of operations.The lower extrem- ity has several angiosomes [see Table 3]. Most of them reach water- shed status in the ankle and foot, which explains why most ischemic ulcers occur below the midcalf area. Although the major leg arteries supply distinct angiosomes of the foot and ankle in a consistent manner [see Figures 1 through 5], they are not immutably segregated from each other and in fact are Anterior Tibial linked by anatomically reliable connections. The links are the so- Artery Angiosome called choke vessels, which represent anastomotic connections between adjacent angiosomes.The significance of these choke ves- sels is twofold: first, they serve as an alternate route of blood flow Anterior Tibial from one angiosome to another in situations of low or impaired Artery flow (e.g., stenosis), and second, they can be used by the surgeon in designing flaps and predicting healing status. It is important to be aware of these connections when treating a wound that may be burdened by local ischemia. As an example, the heel is supplied by two distinct angiosomes, the calcaneal branch of the posterior tib- ial artery and that of the peroneal artery, and native anastomoses exist between these two areas. If there is a necrotic wound in the plantar heel, it follows that both vascular trees must be diseased, because if only one were diseased, the native anastomoses between the two angiosomes would prevent the ulcer from forming.33 As another example, connections normally exist between the anterior perforating branch of the peroneal artery and the anterior tibial artery at the lateral ankle. The astute surgeon can exploit this knowledge to map blood flow to distinct areas of the foot for the Dorsalis Pedis purposes of diagnosis and subsequent reconstructive flap de- Artery sign. 32,33 By alternately compressing flow above and below the arteries, the surgeon can determine whether retrograde blood flow to an adjacent angiosome is occurring (through choke vessels). If it is not, that area should not be used for a distally based flap. Dorsalis Pedis Artery Angiosome Clinical Evaluation and Investigative Studies When confronted with a lower-extremity ulcer, the surgeon should proceed with the physical examination in a systematic, goal- directed manner. It is important to recognize those presentations
  5. 5. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 5 blood pressure cuff. As many as 30% to 40% of diabetic leg ulcer patients have falsely elevated ABIs that may mask an ischemic foot. In nondiabetic patients, an ABI lower than 0.5 mandates further Figure 2 Shown is the angio- imaging to search for possible stenosis or occlusion. In diabetic some of the peroneal artery, patients, measurement of the toe-brachial index (TBI) may be along with the angiosomes of more useful.36,37 Because toe vessels are less frequently affected by the anterior perforating atherosclerotic disease (pedal sparing), toe pressures are a more branch and the calcaneal reliable diagnostic tool in this setting. A value lower than 30 mm branch. Hg is indicative of ischemia. In addition, measurement of the transcutaneous oxygen tension (PtcO2) is extremely helpful, particularly for patients with distal foot ulcers that may be prone to impaired oxygenation from local microangiopathy. PtcO2 levels are also useful for evaluating the Peroneal Artery response to therapy and may help predict healing.13,38 Ischemia is present if the PtcO2 is lower than 30 mm Hg. Peroneal Artery Angiosome Transverse Communicating Branch to Posterior Tibial Artery Anterior Perforating Branch of Peroneal Artery Angiosome TIbioperoneal Trunk Figure 3 Shown is Calcaneal Branch the angiosome of the of Peroneal Artery posterior tibial Angiosome artery, along with the angiosome of the calcaneal branch. Posterior Tibial Artery Angiosome extremity is essential in all patients with problem wounds. Comparison to the contralateral leg (if present) can be very useful. The first step is to assess the appearance of the leg, evaluating such data as color, skin texture, swelling, and temperature. Pulses are then palpated, as is capillary refill. If impaired tissue perfusion seems to be a possibility, these examinations should be supple- mented with more objective diagnostic studies. As a practical mat- ter, pulses in the foot are notoriously difficult to evaluate: different examiners not infrequently report different findings. Among other variables, the skin in the area may be edematous or fibrotic, hin- dering assessment. A pulse may appear diminished to one exam- iner but normal to another. Finally, blood flow may be impaired distal to the ankle, where pulses are typically evaluated. Various modalities are available for diagnosis in this setting; the following Calcaneal Branch are among the more commonly employed and useful ones.34,35 of Posterior Tibial Determination of the ankle-brachial index (ABI) is generally Artery Angiosome helpful, except in diabetic patients.The reason for the exception is that diabetes is associated with increased calcification of the arter- ial wall in the calf, which renders the vessel incompressible by the
  6. 6. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 6 PREPARATION OF WOUND FOR HEALING OR RECONSTRUCTION The first step in wound management is to establish a clean and healthy base. This can be accomplished in a variety of ways. A wound with a heavy eschar and grossly contaminated tissue requires surgical debridement in the OR [see Surgical Treatment, Surgical Debridement, below]. A wound with a mild amount of slough may be effectively debrided with an enzymatic dressing or Lateral Plantar Artery Angiosome even a water jet device (e.g.,Waterpik;Water Pik, Inc., Fort Collins, Colorado). All wounds (except arterial and, usually, vasculitic ulcers) should be debrided down to healthy tissue. This measure resets the clock, so to speak, by effectively converting a chronic wound into an acute one. Because debridement is such a basic step, it tends to be underappreciated, even by surgeons. There are three components of a leg ulcer that must be removed by means of debridement: (1) biofilm and bacteria, (2) callus, and (3) nonviable tissue.39-41 Whereas the role of bacteria in wound infections has long been recognized, it is only comparatively recently that the contributions of biofilm to wound chronicity have come to be appreciated.10,42 Biofilm consists of a sessile communi- ty of multiple bacteria species encased by a protective carbohy- drate-rich polymeric matrix that is resistant to antimicrobial and Lateral immune cell penetration.43 Most wounds are in fact colonized by Plantar Artery bacteria that set up residence in a biofilm. Unfortunately, biofilm is exceedingly tenacious and readily reaccumulates after debride- ment. Thus, proper dressing care consists of dressings that both treat the wound and minimize biofilm accumulation. Bacteria, whether free-floating or (more commonly) incorporat- ed within a biofilm, are extremely detrimental to wound healing, Figure 4 Shown is the angiosome of the lateral plantar artery. Figure 5 Shown is the angio- If the quality of the flow is questionable, either a formal nonin- some of the medial plantar vasive Doppler evaluation or angiography should be performed. If artery. arterial inflow is found to be inadequate, the patient should be referred to a vascular surgeon—ideally, one who is trained in endovascular techniques and distal revascularizations. A careful neurologic examination should be done to evaluate sensation and motor function. This is a particularly crucial in the Medial Plantar management of a compartment syndrome (whether traumatic or Artery Angiosome resulting from a vascular accident). In diabetic patients and those with neurologic disorders, the neurologic examination can deter- mine whether neuropathy contributed to the development of the wound. Lack of protective sensation is diagnosed by tonometry: if the patient is unable to feel 10 g of pressure applied by a Semmes- Medial Seinstein 5.07 monofilament, significant sensory loss has Plantar Artery occurred. This sensory loss prevents patients from registering skin damage that occurs as a result of excessive local pressure from a prolonged decubitus position; tight shoes, clothes, or dressings; biomechanical abnormalities; or the presence of foreign bodies. In neuropathic patients with biomechanical abnormalities, the repet- itive trauma inherent in normal ambulation leads to ulceration as a consequence of the high focal plantar pressures generated during walking. Management: General Principles Current surgical education includes little formal training in the proper management of wounds. Accordingly, it is worthwhile to address some of the basic elements of wound care.
  7. 7. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 7 a INJURY Wound Figure 6 Schematic representation depicts inter- Hypoxia Break in Skin Integrity, play between bacterial levels, oxidative stress, and Bacterial Inoculation parameters of healing in a wound. (a) In the typi- Bacterial cal self-limited inflammatory response in a Colonization healthy healing wound, bacteria are cleared rapid- ly by the body, inflammation is minimized, and Inflammatory the wound progresses to complete healing. (b) In Mediators states of impaired healing (e.g., from local or Resolution (Healed Wound) regional hypoxia, advanced age, presence of a Neutrophils, large eschar, presence of biofilm, or diabetes), Oxidative Burst Macrophages bacterial overgrowth occurs, usually in the form of Reactive Oxygen Species biofilm, and an exaggerated inflammatory Progression of response develops that, instead of being self-limit- Wound to Later ed as in (a), persists, causing cellular bystander Stages of Healing damage and impairing progression of the wound Clearance to later stages of healing. A vicious circle often of Bacteria ensues. Reactive Angiogenesis, Oxygen Reversal of Species Ischemia Resolution of Proteases Inflammation Inflammation Persistent Hypoxia b from Regional Ischemia Insufficient Bacteria Oxidative Burst (as Result of Regional INJURY Wound Hypoxia Ischemia and Immune + Dysfunction) Bacteria Regional Ischemia (Peripheral (Critical Colonization) Vascular Disease, Diabetes, Radiation) Elaboration Perpetuation and of Biofilm, Amplification of Hypoxia Pseudoeschar Proinflammatory State Inflammation, Persistence of Proteases Neutrophils Reactive Oxygen Species Wound Growth Stasis Factors Edema Proangiogenic Exudate Milieu Proteases Cellular Damage Acidity in Wound Free Radicals Zone of Injury particularly when they reach the level of critical colonization.44 use of antibiotics, adequate debridement, and proper dressing Wounds may be classified as contaminated, colonized, critically choices can decrease bacterial numbers and reduce the competi- colonized, or infected.45 These classifications are useful in that they tion for nutrients and resources occurring in wounds contaminat- detail the relation between the bacteria and the patient (or host) ed by bacteria.44 As noted (see above), because most leg wounds and define the level of bioburden (i.e., the cost exacted by bacteria are found in ischemic, aged tissue beds, reduction of the biobur- from the resources of the wound and the patient). All wounds are den can enable healing by restoring the balance between bacterial contaminated to some degree, either by skin flora or by environ- numbers and the nutrients available to healing cells. mental pathogens. It is likely that this level of bacterial contamina- Callus is formed in response to repetitive high pressure, usually tion stimulates wound repair mechanisms by upregulating the over bony prominences on the foot. Once formed, it can further inflammatory response.When the contaminating bacteria begin to concentrate and propagate this excessive pressure on the underly- proliferate, the wound is said to be colonized; however, there is still ing tissues. In addition, the grossly hyperkeratotic skin can act as a no overt reaction by the host at this point. When the proliferating functional barrier to dressings and to migrating healthy ker- bacteria begin to overcome host responses, the wound is said to be atinocytes.Therefore, callus should be removed whenever present. critically colonized. Finally, when the wound provokes an inflam- This can be done with a sharp, heavy scissors or a No. 10 blade; matory reaction by the host to the proliferating bacteria, the wound anesthesia is not required. is said to be infected. It is important to keep in mind that the host’s Nonviable tissue plays no necessary role in ulcer healing. The inflammatory reaction can contribute as much to a wound’s fail- old paradigm of allowing wounds to heal under an eschar is obso- ure to heal as the bacteria themselves do [see Figure 6].2,46 Judicious lete, and the importance of moist healing is now appreciated.
  8. 8. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 8 AMOUNT OF EXUDATE TYPE OF DRESSING for surgery or anesthesia or whose wounds might be exacerbated by surgical trauma (e.g., patients with infected wounds and critical None or Minimal Film, Hydrogel limb ischemia). Enzymatic debridement employs proteolytic agents to break up Mild Hydrocolloid the proteinaceous debris that accumulates within the wound. These agents are efficacious in breaking up limited amounts of necrotic tissue but do not penetrate eschar very well. Some ten- Moderate Alginate derness is associated with their use. The role of ultrasonography in wound debridement is being Large Foam, Other actively investigated. Currently, the MIST Therapy System (Celleration, Inc., Eden Prairie, Minnesota) is approved and reimbursed as a noninvasive debridement device.52,53 Although Copious NPWT the mechanism of action is still not fully known, it is likely that the device works by breaking up biofilm; it may also have other cel- Figure 7 The type of dressing used for a wound is influenced lular effects, such as stimulation of blood flow and direct cell by the amount of exudate present. stimulation. Negative-pressure wound therapy (NPWT) is an important addition to the surgeon’s armamentarium. It acts to encourage Eschars are nature’s biologic dressings, but in the settings of granulation tissue ingrowth through multiple mechanisms—in ischemia, diabetes, and certain other diseases, they can give rise to particular, edema reduction, mechanotransduction, and removal an excessively proinflammatory state characterized by high levels of proteases.54,55 NPWT must be employed properly: it should ide- of free radicals and proteases.47,48 This proinflammatory state is ally be applied to relatively clean wounds, should be applied very hostile to healing, propagates cellular damage, and competes with cautiously to ischemic wounds, and should not be applied at all to host cells for scarce resources. Therefore, all eschar and nonviable wounds with known malignancies. It is useful in converting emer- tissues should be removed. gency wounds for which flap coverage is required into wounds that can be treated more simply. Care must be taken not to overuse or DRESSINGS AND ADJUNCTS TO HEALING misuse NPWT. For example, it should rarely be used before the There are literally thousands of dressings on the market. The wound is completely closed. At some point, the wound will be vast majority of these products have not yet been proved superior small enough that it either can heal with simpler, less expensive to gauze by well-designed, randomized, prospective, controlled dressing changes or can be closed primarily or with a simple skin clinical trials.This is not to say that they are useless; rather, it is to graft. remind practitioners that there are intense commercial and clinical Hyperbaric oxygen (HBO) is a useful, albeit often maligned, needs driving the marketing of wound dressings and that claims of wound care modality. The lingering suspicion surrounding its use efficacy should therefore be taken with a grain of salt. Most today results not from lack of utility but from inappropriate use in wounds will heal, even if the dressing does not have the efficacy the past. The benefits of HBO include improved cellular oxygen claimed. The main goal of a dressing should be maintenance of a delivery, maintenance of cellular metabolism through preservation moisture level optimized to facilitate wound healing and encourage of cellular adenosine triphosphate (ATP) levels, increased angio- autolytic debridement.49 Other goals include coverage of the genesis, reduced oxidative stress from persistent ischemia, in- wound (to prevent soilage) and delivery of antimicrobial agents creased perfusion, increased collagen synthesis and fibroblast func- (e.g., silver ions and cadexomer iodine). It is important to use the tion, and reduced infection.56 It is likely to be of particular value in proper dressing for a given wound [see Figure 7]: if the wound dries patients with irradiated ulcers or diabetic feet. Broadly speaking, out, the healing cells may die, and if it is too moist, bacterial over- HBO will be useful if an increase in tissue PtcO2 can be demon- growth and skin maceration may result. strated when the patient is given supplemental oxygen57-59; typical- Autolytic debridement consists of facilitating the body’s removal ly, an increase of 10 mm Hg suggests that HBO may be worth try- of dead tissue and cells by providing an optimal (usually moist) ing. HBO does require a facility with dedicated staff, and there are wound environment. If a proinflammatory eschar is prevented risks associated with its use, some of them life-threatening. from forming (by preventing biofilm accumulation and minimiz- Another option is a tissue-engineered dressing, such as Apligraf ing slough buildup and desiccation), the body’s own phagocytic (Organogenesis Inc., Canton, Massachusetts), which is a cultured mechanisms will gradually remove the impediments to healing. bilayered dressing of human foreskin–derived fibroblasts and ker- Wound healing will then follow a normal trajectory. Film dressings, atinocytes grown on a bovine collagen matrix.60 Because the cells hydrogels, and other moist products may be used to accomplish are not autologous, they are not ultimately incorporated into the autolytic debridement. wound but may persist within it for several weeks. Like the cells in A particularly effective debridement method that is enjoying a a skin graft, the cells in Apligraf appear to produce a panoply of resurgence in popularity is the use of maggots.50,51 Because of the growth factors, which accounts for the efficacy of this dressing in strong propensity of these organisms for ingesting dead tissue, this ulcer care. In addition, Apligraf is easy to apply. Apligraf is form of debridement is extremely selective. The maggots are approved for use in both diabetic foot ulcers and venous stasis placed on the wound and contained within the wound’s confines ulcers, and it is widely used off label in other types of wounds.61,62 with net gauze; every 2 to 3 days, they are changed. Although mag- Another useful tissue-engineered dressing is Integra Bilayer Matrix gots cause considerable social discomfort among caregivers, they Wound Dressing (Integra, Plainsboro, New Jersey), an acellular are actually a very good option for wound bed preparation in scaffold of glycosaminoglycans and collagen. Integra serves as a patients with severe comorbid conditions, and in most cases, they three-dimensional matrix within which cellular ingrowth takes are remarkably well tolerated. Candidates for maggot debridement place, and it eventually becomes completely incorporated within a include patients with severe limb ischemia who are not candidates wound or defect; once incorporated, it is covered with a thin auto-
  9. 9. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 9 logous skin graft. Integra may be used to resurface exposed bone, management of foot wounds, particularly in diabetic patients, that tendon, and orthopedic hardware, and in some case, it may render must be taken into account. a flap procedure unnecessary.63 One caveat to the use of tissue- Three main types of flaps are employed in the lower extremity: engineered dressings is that they must be applied only to wounds local random-pattern flaps, local pedicled flaps, and free tissue that are free of infection or significant bacterial colonization. transfers [see 3:3 Open Wound Requiring Reconstruction and 3:7 Another drawback is that they are expensive and thus must be Surface Reconstruction Procedures]. used strategically. Local random-pattern flaps Local random-pattern flaps SURGICAL TREATMENT include such flaps as Z-plasties, advancement flaps (e.g., V-Y), rotation flaps, and transposition flaps.24 These are extremely use- Surgical Debridement ful for closing small defects of the foot. One limitation to their use Debridement is not always a surgical procedure. In fact, the is the tautness of the skin in this area, which limits flap mobility. majority of leg ulcers can be effectively managed with nonsurgical With imaginative design and careful execution, local random-pat- debridement, typically in the form of dressing changes or wound tern flaps can be employed for any small foot wound. ointments that encourage the body to heal (see above). Often, however, surgical debridement is the best option. It is Local pedicled flaps Local pedicled flaps are employed for extremely effective, but it is also the most invasive type of debride- coverage in both the leg and the foot, especially for closure of larg- ment, the most likely to cause bleeding, and the most painful er foot wounds and deeper wounds that expose bone, capsule, or (except when done in an insensate foot, such as that of a diabetic hardware. They are reliably based on axial vessels, typically patient).Whether performed in the OR or in the clinic, the goal of branches of angiosomes.The following are among the more com- debridement is to remove all nonviable, infected tissue and reach monly used local pedicled flaps.68,69 bleeding tissue or viable fat, tendon, or fascia. The benefits of a well-performed debridement are tremendous, including excision 1. Gastrocnemius flap.This flap is used to cover proximal defects of callus (which augments pressure during ambulation), removal in the knee and the proximal third of the leg. As a rule, half the of biofilm and necrotic tissue (which amplifies the inflammatory muscle is used.The medial gastrocnemius is generally preferred host response and competes with the healing tissue for oxygen and unless the wound or defect is laterally based. nutrients),44 conversion of a chronic wound to an “acute” wound, 2. Soleus flap.This flap (preferably from the medial portion of the stimulation of cell proliferation (by injuring healthy cells and muscle) is used for coverage of deep wounds in the middle third releasing growth factors into the wound environment), and rid- of the leg. ding the wound bed of senescent cells and chronic wound fluid 3. Reverse sural fasciocutaneous flap. This flap is an option for (which has been demonstrated to contain growth factor–neutraliz- defects of the lower leg and ankle.70 A delayed procedure is pru- ing proteases).64,65 dent in patients with impaired or uncertain vascular status or A novel form of surgical debridement is hydrosurgery (VersaJet; comorbid conditions (e.g., diabetes or renal failure).71 Some Smith & Nephew, Hull, United Kingdom), which involves using a surgeons will not use a reverse sural flap, because the donor site “water knife” for selective removal of infected or devitalized tis- in the proximal calf must be covered with a skin graft, which sue.66 It is expensive, but its benefits are formidable, and it is like- could hinder the wearing of a prosthesis if a below-the-knee ly to see expanded use in the future. amputation proves necessary. This limitation can, however, be addressed by using an anteriorly based skin flap for the ampu- Reconstruction with Grafts or Flaps tation to cover the calf muscles. The reverse sural flap is an The optimal closure technique for a given wound depends as extremely versatile one that usually covers heel defects well, much on the wound type as on the patient. In evaluating different particularly in patients with tenuous vascular inflow, without reconstructive options, plastic surgeons often rely on the concept requiring microsurgical skills or facilities. of a reconstructive ladder (or elevator). In general, the simpler or 4. Other flaps for the leg. Other options in the leg include wide- less invasive techniques are considered first (representing the low- based adipofascial flaps that can be rotated to cover a defect est rungs on the ladder). If simpler techniques prove unsuitable or and skin grafted to achieve cutaneous coverage.72,73 These do inadequate, decision-making proceeds to consider increasingly not have a reliable axial blood supply, particularly in patients complex and morbid options (successively higher rungs), culmi- with vascular disease74; they mostly have a random pattern of nating in microvascular free flaps or transfers (the top rung). As blood flow. may be apparent, this schema is simplistic and does not always 5. Medial plantar flap.75 This flap is particularly well suited to cov- apply to the lower extremity, where often the first choice (or the erage of calcaneal defects. It brings thick, glabrous skin that will only real choice) is a complex free flap.The concept of the recon- resist breakdown and the shearing forces affecting the heel. If structive elevator is more useful in the leg, where the surgeon can the medial plantar nerve is incorporated, the flap will be sen- directly choose the option best suited for a particular wound or sate.The medial plantar flap can also be advanced distally into defect.67 the forefoot if necessary, typically in the form of a V-Y advance- Skin grafts are often used to close shallow wounds or wounds in ment flap. the non–pressure-bearing instep of the foot. If a decision is made 6. Abductor digiti minimi flap.69 This flap is best used for small to close a foot or leg wound surgically, several principles should be defects of the lateral ankle and heel, particularly wound dehis- kept in mind. The main one is that the simplest solution is usual- cences after orthopedic procedures. It is dissected in a distal-to- ly, but not always, the best. It is important to leave room for cre- proximal direction and transposed to cover proximal defects. ativity in the use of flaps.There are numerous different local flaps The donor site is closed primarily and requires a skin graft for that are extremely useful (see below). Most wounds do not require coverage. microsurgical flaps, but occasional ones do benefit from micro- 7. Abductor hallucis brevis flap.With this flap, as with the abduc- surgery. There are also important issues related to orthopedic tor digiti minimi flap, the dominant arterial pedicle is situated
  10. 10. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 10 rather proximally, allowing the distal abductor hallucis brevis to cedure that preserves as much of the foot’s length as possible while be dissected completely free and rotated to cover defects of the also maintaining a well-balanced walking surface with thick plan- medial heel and ankle. Again, a skin graft is required for cover- tar skin. Fundamentally, it is a reconstructive procedure: the vas- age of the donor site. cular supply to both the plantar and the dorsal flap must be 8. Extensor digitorum brevis flap. This flap is a multipennate flap ensured prior to closure, and the balance of the foot tendons must consisting of several slips of muscle that inserts via tendons on be addressed.76 The plantar metatarsal arteries, which supply the the second through fifth toes. It is used for coverage of dorsal plantar flap, must be kept intact by avoiding excessive undermin- foot and ankle defects. ing or indiscriminate use of the electrocautery. If the flap appears compromised after closure, the flap sutures should be released, Other useful muscle flaps include the flexor digitorum brevis and completion of the flap procedure should be delayed for sever- flap (for heel defects) and the flexor digiti minimi musculocuta- al days to encourage increased neovascularization. NPWT may be neous flap. used as a temporizing measure to bridge the wound before formal closure. After a transmetatarsal amputation, the triceps surae may Free tissue transfers The rich variety of flaps available for be lengthened to compensate for the loss of ankle dorsiflexion that coverage of leg and foot wounds has led to a decline in the use of results from removal of the attachment points to the toe extensor microsurgical free flaps in the lower extremity.The development of tendons.24 NPWT has also contributed to the declining need for free flaps, in that many wounds are currently being downstaged with NPWT to enable eventual closure with a technique farther down the recon- Management of Specific Types of Lower-Extremity Ulcer structive ladder. Nevertheless, there remain certain wounds in all In the early stages of management, it is important to focus on areas of the leg and foot for which free flaps may still be useful or the patient’s overall health status, with a particular emphasis on the even preferable, such as large defects and wounds characterized by presence or absence of sepsis. It is also vital to determine whether significant exposure of bone or hardware. Flow-through free flaps adequate vascularity is present to enable healing. Most wounds are also commonly used to achieve revascularization and wound benefit from debridement, whether biologic (i.e., dressings and coverage simultaneously. Occasionally, free flaps are used for wound care) or surgical. At the same time, normalization of sys- wounds with venous insufficiency or lymphedema in an attempt to temic derangements is undertaken. A decision is made whether to improve these conditions by restoring lymphatic channels or com- treat the wound surgically. In most instances, this does not have to petent venous drainage.The free flaps used in the lower extremity be done right away. Surgical wound closure, when feasible, is best may be either fasciocutaneous or muscle flaps. Most studies have done after a period of optimization. not found either type of flap to be superior to the other for treat- In addition to these considerations, which are common to all ment of areas of infection. In general, however, fasciocutaneous leg ulcers, there are aspects of care that are specific for different flaps are preferred for wounds on the sole of the foot, which are ulcer types. Accordingly, in what follows, I focus on specific care exposed to pressure and shearing forces, whereas muscle flaps are of the most prevalent types of leg ulcer—namely, those resulting preferred for deep wounds. from arterial insufficiency, those associated with diabetic neu- Amputation rarthopathy, those resulting from venous stasis, and those of inflammatory origin. On occasion, amputation proves necessary [see 6:20 Lower- Extremity Amputation for Ischemia].76 Factors such as advanced age, ULCERS RESULTING FROM ARTERIAL INSUFFICIENCY uncontrolled diabetes, sepsis and gangrene, unreconstructable Most arterial leg ulcers occur in the elderly. A nonhealing ulcer blood vessels, and renal failure are all associated with a higher risk is one of the most common presentations of peripheral vascular of amputation. Nevertheless, a focused, multidisciplinary approach disease, the incidence of which is highest in men older than 45 to wound care should be able to reduce amputation levels sub- years and women older than 55 years. Modifiable risk factors for stantially and achieve limb salvage rates higher than 90%. Overall, peripheral vascular disease include smoking, hyperlipidemia, the most frequently performed amputations are toetip amputa- hypertension, diabetes, and obesity. tions. Of these procedures, the most common is amputation of the In most instances, the diagnosis is suggested by the physical tip of the great toe. This operation is done to treat the claw-type examination. Arterial leg ulcers generally occur in a stereotypical deformity seen in diabetic patients with an intrinsic-minus foot, distribution that is well explained by the angiosome concept men- whereby the toe becomes permanently flexed as a result of the pull tioned earlier [see Anatomic Considerations, above], most com- of the flexor hallucis longus tendon.The tip amputation may have monly developing over the toes, heels, and bony prominences of to be closed with a fishmouth-type incision or a V-Y advancement the foot. It is worth noting that a heel ulcer typically results if there flap from the plantar surface. In addition, it may be necessary to is disease in the distributions of both the peroneal artery and the advance the flexor hallucis longus tendon and perform a volar cap- posterior tibial artery, as a consequence of the dual blood supply sular release to minimize recurrence. to the posterior heel from these vascular territories.33 Ulcers in the Amputations of the toe rays are frequently performed, most toes result from the diminished distribution of blood to these ter- commonly in diabetic patients but also in patients with minal vascular beds. An ulcer in the setting of arterial insufficien- osteomyelitis of the metatarsal heads. Rebalancing the pull of the cy is a symptom of the decreased blood flow and may be associat- extrinsic tendons is crucial for preventing redistribution of the mal- ed with rest pain or claudication.The metabolic demands of intact adaptive forces to adjacent rays and subsequent propagation of ser- skin are less than those of an open wound, but even so, the ial ulcers in these areas.Therefore, the peroneus brevis and tibialis impaired blood flow renders the skin thin, atrophic, hairless, and anterior insertions should be reattached to the cuboid or the cunei- dry in the affected extremity. Patients usually experience significant form for proximal fifth and first ray amputations, respectively.24 pain, which is relieved by dangling the leg over the bed at night. Most amputations of the foot are performed at the trans- The ulcer has a sharply demarcated appearance, with a paucity of metatarsal level. Transmetatarsal amputation is a very useful pro- granulation tissue. The wound bed is pale or pink and typically
  11. 11. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 11 Patient has possible arterial insufficiency ulcer Establish diagnosis of arterial insufficiency (pulses, ABI, PtcO2, toe pressures, Doppler examination, arteriography, magnetic resonance angiography). Establish presence or absence of comorbid conditions (e.g., diabetes, venous disease, renal failure), and address these conditions when possible. Perform revascularization when it is warranted and possible (i.e., ABI < 0.5, chronic limb ischemia, rest pain and/or gangrene), using bypass techniques (including distal bypass), angioplasty, or, in selected cases, endovascular techniques. Control of bioburden Optimization of perfusion Care of wound Give systemic antibiotics Ensure adequate hydration, control pain, Choose dressings so as to ensure if signs or symptoms of keep limb warm, control edema, and moist healing. Promote autolytic infection are present. provide supplemental O2. debridement. Remove biofilm. Consider hyperbaric oxygen only after If wound bed is otherwise prepared revascularization or if PtcO2 > 10 mm Hg and healing is stalled or slow, consider with patient breathing 100% O2. growth factors or biologic dressings. Debridement Optimization of systemic parameters Surgical treatment Perform selectively. If dry gangrene Options include or dry eschar is present, leg should Encourage smoking cessation, treat other comorbid conditions, and ensure adequate nutritional status. • Grafts • Flaps first be revascularized. Provide patient education and initiate preventive • Amputation (for dry gangrene measures as appropriate. or osteomyelitis) In most cases, surgery is deferred until local blood flow is restored. Full restoration after Figure 8 Algorithm illustrates management of arterial insufficiency ulcers. revascularization may take 2 to 4 weeks. lacks the red color associated with a hypervascular healing bed. At the tissue level, chronic regional ischemia results in atrophic Pulses are usually diminished. Any patient with decreased pulses changes to the skin and soft tissues.The terminal nature of the vas- at the ankle (signaling insufficiency of the dorsalis pedis, the pos- cular tree in the foot, with the distal foot and toes being less well terior tibial artery, or both) should be referred for vascular studies. perfused than the calf and thigh, along with the effects of gravity In practice, given the wide interindividual variation in the ability to and the rigors of ambulation, means that these downstream areas palpate a pulse accurately, it is advisable to set a fairly low thresh- bear the brunt of the effects of upstream atherosclerosis. In the set- old for obtaining studies such as an ABI or a TBI. In general, arte- ting of a minor injury, the atrophic skin is more liable to progress to rial leg ulcer patients with an ABI lower than 0.9 or higher than 1.2 a full-thickness injury in the distal foot and toes than in more prox- or with a PtcO2 lower than 30 mm Hg should be referred to a vas- imal locations and, indeed, is more likely to tear in the first place. cular surgeon. As mentioned (see above), synthesis of new tissues and deposition Quite often, the etiology of an arterial leg ulcer is not purely of matrices and collagen, along with collagen crosslinking, are nec- ischemic but includes contributions from other conditions, such as essary for ulcer healing. These are all rate-dependent processes, diabetes, venous insufficiency, neuropathy, and renal failure.These with oxygen being the necessary variable. Unfortunately, the ulcers of mixed etiology are particularly challenging to treat, and it impaired tissue perfusion means that the ulcer bed will not receive is all too common to find a supposedly chronic wound whose an adequate supply of oxygen and nutrients to support tissue chronicity actually resulted from an earlier failure to establish the growth. In addition, because oxygen is necessary for the neutrophil leg’s vascular status. burst, arterial ulcers are especially predisposed to infection.11 At the cellular level, the cause of an arterial ulcer goes beyond These considerations help explain the typical appearance of the simple lack of sufficient oxygen supply to a cell. For example, ulcers resulting from arterial insufficiency: the sharply demarcated it is known that sublethal ischemia is much more detrimental to boundaries (attributable to the “on/off” borders between the aged cells and diabetic cells than to young cells.77,78 Lack of ATP defect and unwounded skin, with a minimal healing interface); the and inadequate clearance of metabolites result in poor healing and dry wound beds, with minimal transudate and exudate; the pale aberrant inflammation. Because healing is an anabolic process, granulation tissue, indicative of a hypovascular state; the changes much more energy is needed for healing than for tissue mainte- in the appearance of the surrounding skin (see above); and the nance and homeostasis. The persistence of noxious metabolic reduced capillary refill time. byproducts that are not cleared by the circulation may be a cause In the treatment of a wound with an arterial component [see of the pain commonly associated with these wounds.79 Figure 8], the sine qua non is revascularization: a wound typically
  12. 12. © 2008 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 27 Lower-Extremity Ulcers — 12 will not heal if the leg’s blood supply is not improved.11 Therefore, DIABETIC ULCERS the urgent decision to be made at this point is whether revascular- There is a growing tendency to misapply the term diabetic foot ization is feasible. It should be kept in mind that the decision as to ulcer. Many practitioners use this term to describe any wound that whether an extremity is a candidate for revascularization should be occurs in the leg of a diabetic patient, but strictly speaking, it refers made only by a vascular specialist who is comfortable with or has only to a neuropathic plantar ulcer that originally results from pres- access to newer modalities and procedures (e.g., distal bypasses sure necrosis. Diabetic patients also have ischemic wounds and and endovascular techniques). Noninvasive means of revascular- venous insufficiency ulcers, but these lesions are not true diabetic ization are useful in high-risk patients. foot ulcers. It is important to keep in mind that diabetic foot ulcers After revascularization, there is a lag phase before the ischemia is may have several different presentations. For example, some are reversed in the distal leg and foot.Typically, a rise in PtcO2 is seen 1 due solely to neuropathy, whereas others are due to ischemia in to 2 weeks after surgical revascularization and is delayed after conjunction with neuropathy. Diagnosing a diabetic foot ulcer is angioplasty.15 In patients with foot ulcers, foot pulses must be straightforward; however, evaluating the vascular supply to the foot restored if the ulcers are to heal.The wound must be managed dur- and determining how much neuropathy and functional microan- ing the weeks after revascularization, and indeed for months to giopathy contribute to the wound’s failure to heal are not always so years afterward. It should be noted that techniques associated with straightforward. Evaluation of the diabetic foot is addressed in lower long-term patency rates can nevertheless be useful if they greater detail elsewhere [see 6:7 Diabetic Foot]. enable healing of an open wound or amputation site. Once the Currently, two diabetic foot ulcer classification systems are wide- ulcer is healed, the likelihood that a new wound will develop in the ly used, the Wagner system and the University of Texas (UT) sys- area diminishes (because of the lower energy requirements of tem [see Table 4].83-85 At present, the UT system appears to be a bet- healed skin in comparison with those of a healing wound). ter predictor of ultimate wound and foot outcome86 and is more Any significant comorbid conditions, such as diabetes or venous widely used in wound centers. A major shortcoming of the Wagner stasis disease (see below), should be addressed. Steps must also be system is that the presence of ischemia is not a part of early-stage taken to prevent or control infection, which can cause rapid deteri- ulcers. oration in an arterial ulcer. If signs of local or systemic infection are The pathology of diabetic foot ulceration is multifactorial. noted, treatment with systemic antibiotics should be initiated Chronic hyperglycemia leads to advanced glycosylation end prod- promptly. Unless grossly infected tissue (e.g., wet gangrene) is pre- ucts and crosslinking of proteins, everntually resulting in foreshort- sent, it is best to defer debridement until the vascularity of the area ening of tendons. Relative ischemia (particularly in the vasa vaso- is ensured: debridement while the blood flow to the area is still rum), coupled with the glycosylated protein buildup, leads to sen- impaired may promote further ischemia and lead to the formation sory and autonomic neuropathy. The autonomic neuropathy leads of a larger ulcer.11 Dressings applied to ischemic ulcers typically to anhidrosis and ultimately to fissuring, which affords bacteria a must have moisture added in the form of hydrogels as the hypo- means of entry through the skin. In addition, it leads to hyperker- vascular wound bed desiccates. An enzymatic dressing can also be atosis, which increases the pressure over pressure points and useful for gentle debridement of nonviable tissue. Systemic factors (e.g., global hypoxia, enhancement of cardiac output, pain control, and warmth) are important as well. In patients who respond to an Table 4 Staging Systems for Diabetic Foot Ulcer oxygen challenge, HBO should be considered and offered if avail- able; however, it should not be employed in place of surgical revas- Grade 0: impending skin lesion, presence of predisposing cularization if the latter is an option. bony deformity, or healed ulcer Final surgical treatment, in the form of flaps or skin grafts, is Grade 1: superficial skin ulcer that does not involve subcutis deferred until blood flow is ensured. Occasionally, it is possible to Grade 2: full-thickness ulcer that exposes bone, tendon, perform what is termed extended limb salvage, wherein a bypass Wagner classification ligaments, or joint capsule graft to the leg is performed at the same time that a microvascular system Grade 3: full-thickness ulcer with presence of osteitis, free flap is used to cover a large defect.80-82 With advances in osteomyelitis, or abscess Grade 4: gangrenous digit wound care products and the introduction of NPWT, however, Grade 5: gangrene severe enough to necessitate foot most procedures can be staged. Flap procedures are typically amputation undertaken after a period of days to weeks, once the oxygen sup- ply is restored. Grade I-A: noninfected, nonischemic superficial ulceration Grade I-B: infected, nonischemic superficial ulceration These patients are nevertheless at high risk for amputation, typ- Grade I-C: ischemic, noninfected superficial ulceration ically as a consequence of progressive atherosclerotic disease. Grade I-D: ischemic and infected superficial ulceration Patients with unreconstructable peripheral vascular disease (partic- Grade II-A: noninfected, nonischemic ulcer that penetrates ularly common in the setting of renal failure) or extensive tissue loss to capsule or bone or gangrene usually require a major amputation. Even after the Grade II-B: infected, nonischemic ulcer that penetrates amputation, attention must be paid to the vascular status of the to capsule or bone University of Texas Grade II-C: ischemic, noninfected ulcer that penetrates amputation site. If the blood flow to the skin has not been ensured, diabetic foot wound to capsule or bone the amputation incision will be prone to breakdown and necrosis. classification system Grade II-D: ischemic and infected ulcer that penetrates In fact, as many as 25% of patients who undergo surgical revascu- to capsule or bone larization experience a postoperative wound complication in the Grade III-A: noninfected, nonischemic ulcer that penetrates to bone or deep abscess surgical incision. This finding underscores the points that a revas- Grade III-B: infected, nonischemic ulcer that penetrates cularized limb usually is still ischemic and that the surgical proce- to bone or deep abscess dure must be done meticulously and with careful handling of soft Grade III-C: ischemic, noninfected ulcer that penetrates tissue. Application of the angiosome concept can be extremely use- to bone or deep abscess ful for determining the optimal amputation level and assessing the Grade III-D: ischemic and infected ulcer that penetrates to bone or deep abscess potential for healing.32