Surgical Management of Chronic Wounds

Disclosure: Dr. Granick was a medical consultant for Smith & Nephew Inc (Largo, Fla)

Chronic wounds represent a huge burden on the population in the United States in terms of both morbidity and annual health care expenditures. An estimated 6.5 million people in the US are afflicted with chronic ulcers due to pressure, venous insufficiency, or diabetes, and health care costs run in the billions of dollars each year. Even with successful treatment, the recurrence rate for ulcers ranges from 66%–90% depending on the etiology. The wound care marketplace has been inundated with products ranging from enzymatic creams, growth factors, and dressings to sophisticated skin substitutes, negative pressure wound closure devices, and high-pressure cutting waterjets. Medical management of wounds has traditionally focused on the use of topical agents such as gauze dressings and papain/urea or collagenase-based creams, while surgical management has concerned itself with the physical excision of nonviable tissue. The ultimate goal of wound therapy, however, is common to both—to create a clean, well-vascularized wound bed that can progress through the stages of wound healing. The purpose of this article is to describe a surgical approach to the assessment and management of chronic wounds with a focus on the role of surgical debridement.

Chronic Wound Assessment
Before deciding on a treatment strategy, a thorough history and physical should be performed with special attention aimed at elucidating the factors contributing to poor wound healing. A history of previously attempted therapies should be elicited as well, as popular topical agents, such as peroxide and iodine, have actually been shown to impede healing.¹ The most common factors responsible for wound chronicity include local infection, the presence of necrotic tissue or debris, repeated trauma, and disease states such as diabetes and peripheral vascular disease. Establishing the etiology of a chronic wound is important because surgical debridement may not be the initial treatment of choice in some cases. Wounds due to arterial insufficiency, for example, should not be aggressively debrided until blood supply is restored to the ischemic wound bed. Similarly, debridement of venous insufficiency ulcers must be accompanied by compression therapy or venous surgery to correct the vascular derangement in order for healing to occur.² Conversely, autoimmune diseases, such as systemic lupus erythematosus or pyoderma gangrenosum, may produce inflammatory lesions that would be better served by medical management of the underlying condition. Finally, Marjolin’s ulcer should be considered in persistent, long-standing wounds, and a biopsy performed to determine the presence of malignancy and the extent of resection required.
Examination of the wound should include a careful determination of wound size and depth. The level of exposed tissue should be noted, as well as the presence or absence of cellulitis or other signs of infection. A probe can be used to explore deep or tunneled wounds—if bone is contacted, there is an 85% chance that osteomyelitis is present.³ A thorough neurovascular exam should also be performed. Blood flow to the tissue is assessed by palpation of distal pulses or Doppler signal evaluation. Sensation to the area can be evaluated using a 5.07 Semmes-Weinstein filament. An inability to feel 10-g of pressure indicates loss of protective sensation.⁴ After wound therapy is initiated, healing progress should be monitored with weekly measurements. Normal healing results in a 10%–15% reduction in wound area per week.⁵ If the patient’s progress consistently falls short of this goal, consideration of alternative healing strategies is warranted.

Wound Bed Preparation and the Role of Debridement
Chronic wounds are trapped in an inflammatory stage of wound healing and cannot progress further because of various inhibitory factors. The primary role of surgery in managing these wounds is to eradicate the inhibitory elements and prime the wound bed for healing either by secondary intention or coverage with skin or soft tissue. The concept of wound bed preparation consists of more than excising tissue. Wound bed preparation is a comprehensive approach that seeks to eliminate the numerous factors that impede wound healing. It is described by the acronym “T.I.M.E.” where “T” refers to the removal of unhealthy tissue, “I” to the control of infection by reducing the bacterial burden of the wound, “M” to the maintenance of moisture balance by finding an equilibrium between decreasing wound edema and exudation and keeping the tissue moist, and “E” for the advancing wound edge.⁶
Debridement plays a key role in removing bacteria, necrotic tissue, and foreign material from a wound. While all wounds are colonized with bacteria, the development of infection depends on host immune competence and the size of the bacterial load. In an otherwise healthy host, a wound with 10⁵ microorganisms or less per gram of tissue should go on to heal successfully.⁷ At levels higher than this, a wound is considered infected and healing is impaired. The mechanism involves the induction of matrix metalloproteases, which degrade necessary growth factors, chemotactants, and new granulation tissue. This hostile environment further promotes the proliferation of bacteria, which produce additional inhibitory enzymes and deprive the local tissue of vital nutrients and oxygen. The presence of a foreign body in a wound decreases the number of bacteria necessary to cause clinical infection by a factor of 10³. Devitalized tissue not only provides a growth medium for microorganisms, it results in the release of endotoxins that inhibit fibroblast and keratinocyte migration into the wound. Thus, debridement of necrotic tissue and debris effectively removes inhibitory healing factors at the cellular and molecular levels as well and is critical for healing to occur.

Surgical Debridement
The goal of surgical debridement is to convert a chronic wound into an acute one that will progress through the sequential steps of wound healing in a timely fashion. Debridement traditionally proceeds systematically from the periphery to the center of the wound and involves the methodical excision of nonviable tissue until healthy, bleeding tissue is reached. Concerns about the ease of reconstruction should not interfere with obtaining adequate debridement, as an inadequately debrided wound will again fail to heal. Sequential debridement may be necessary in some cases when the extent of debridement required cannot be predicted at the initial procedure. In these instances, it has been shown that healing is improved when debridement is performed weekly rather than less frequently, probably due to the routine removal of wound healing inhibitors.⁸

Debridement can be performed either at the bedside or in the operating room. Wound size, plans for wound closure, and patient factors such as the presence or absence of sensation will dictate which is preferred. Regardless of the operative setting, atraumatic surgical technique and delicate tissue handling should be employed to avoid damaging the surrounding healthy tissue. Tools used for debridement include toothed pickups, which are useful for grasping tissue without crushing it; a scalpel, for removing thin layers of tissue; sharp scissors, for dissecting necrosis away from the wound bed; and a curette, for removing accumulated coagulum. Recent innovations include the waterjet hydrosurgery system (Versajet^™, Smith & Nephew, Largo, Fla), a hand-held device that forces a small stream of saline across an 8-mm to 14-mm gap at pressures of up to 15,000 psi.⁹ This high-power stream ablates tissue tangentially to the wound surface, and the vacuum created around the stream by the Venturi effect immediately removes the fluid and debris.
The introduction of the hydrosurgery device has led to a paradigm shift in the surgical management of wounds.¹⁰ Conventional debridement is performed in a centripetal fashion and involves the removal of a margin of healthy tissue around the wound. The advantages of the hydrosurgery device are its versatility and the ability to precisely control the depth of tissue removed. The cutting head is easily maneuvered to reach into small or deep wounds and still lie flat on the wound surface, allowing debridement to begin in the center of the wound and proceed centrifugally until all necrotic tissue has been excised. The result is a more thorough debridement along with maximal preservation of the healthy surrounding tissue.¹¹ A retrospective study of 62 patients, 40 of whom underwent debridement with the hydrosurgery device, showed that these patients required significantly fewer procedures compared to the group (22) who were treated with conventional debridement techniques.¹² In addition, a cost-benefit analysis revealed that use of the hydrosurgery device results in a savings of approximately $1900 per patient compared to using conventional debridement techniques.¹²
Skin and subcutaneous tissue. Debridement of any structure should proceed in a logical fashion with meticulous attention to detail. When debriding skin, all nonbleeding skin should be excised until bright red, punctate bleeding in the dermis can be seen. The presence of clotted blood in the dermis indicates that the microcirculation to the skin has been disrupted. Skin that is insensate or does not blanch is unlikely to be viable and should be removed as well. Debridement of subcutaneous fat should be carried out until soft, shiny, yellow fat is encountered. Care should be taken not to undermine the tissue, as it risks damaging arterial perforators to the overlying skin. Sensory nerves that are encountered can either be preserved if soft tissue coverage is planned, or sacrificed by trimming them and allowing them to retract or burying them in the underlying tissue.
Fascia, muscle, and tendon. Necrotic fascia has a dull, soggy appearance in contrast to the shiny tautness of healthy fascia. Necrotic fascia must be debrided, but effort should be made to preserve any fascia that appears viable, as it functions as a barrier to bacterial invasion of the underlying muscle. Healthy muscle has a firm, beefy red appearance and contracts when stimulated, whereas nonviable muscle is dull, congested, and friable. A thorough but conservative approach should be taken toward debriding muscle, removing only that which is obviously infected or is no longer bleeding. Tendon debridement should be approached with similar restraint, as sacrifice of a tendon leads to loss of function. If the tendon to be debrided is large, an attempt should be made to preserve any portion that appears viable. The paratenon should also be preserved if possible, as it prevents tendon desiccation and is the structure’s only source of nutrition. Necrotic or infected tendon appears dull and boggy, as opposed to the shiny firmness of healthy tendon. If infection is suspected, the tendon sheath should be palpated and milked towards the open portion of the wound. If pus is expressed, the sheath must be opened both proximally and distally to permit adequate drainage.
Bone. Debridement of bone can be performed with instruments, such as rongeurs and chisels, or with power tools. Necrotic bone is soft, discolored, and nonbleeding, and should be debrided until punctate bleeding can be seen in the cortex (paprika sign). Exposed bone in a chronic wound is likely to be osteomyelitic. Any bone suspected of harboring osteomyelitis should be removed, and cultures should be obtained of both the debrided bone and the proximal normal bone. An infectious disease specialist should be consulted and an appropriate course of antibiotic therapy begun.
After adequate debridement has been performed, a pulsed lavage system should be used to irrigate the wound. The pressure generated by these systems is highly effective in further removing bacteria and loose tissue. This step is unnecessary when the hydrosurgery device is used to debride the wound.¹³ While some practitioners advocate adding antibiotics to the lavage fluid, studies have shown that normal saline is adequate, as the added antibiotics do not result in decreased bacterial counts in the wound.¹⁴ Following irrigation, the wound can be closed immediately or left open to either heal secondarily or be closed with a delayed reconstruction. This would also be the time to apply advanced therapeutic options.

Wound Closure
The goals of wound reconstruction are to preserve tissue form and restore functionality. The reconstructive ladder describes a hierarchical approach to wound closure, beginning with the simplest option, direct closure, and ending with the most complex, microvascular free tissue transfer. Free tissue transfer is primarily used for coverage of problem wounds that lack a graftable wound bed and in which no local tissue options are available. A flap provides bulk to fill in the defect and, more importantly, brings in healthy, well-vascularized tissue from a distant site. Healing of any type of reconstruction in a compromised area is of concern. Thus, the underlying pathology of wounds with an identifiable cause must be addressed before reconstruction is attempted.

Conclusion
The surgical approach to chronic wound management focuses on debridement. Adequate debridement releases the wound from the inflammatory stage of healing by removing inhibitory factors such as bacteria, necrosis, and debris, and converts the wound surface into one that is primed for healing. Surgery is a method of wound management that is often overlooked in favor of medical management. While many methods of wound bed preparation exist, surgery is the most efficient, and perhaps, the most effective modality. Surgery offers immediate, definitive treatment, whereas medical approaches can take months to achieve comparable results. Recent innovations, such as the hydrosurgery device, have revolutionized the concept of surgical debridement and have increased the quality of patient care. Much effort continues to be devoted to the development of novel wound healing strategies, and it is likely that great advances in wound care will be made in the near future. It is the authors’ belief that all chronic wounds should be surgically debrided to achieve wound healing or to facilitate other healing strategies.