INTRODUCTION
Stemming from Middle French “desbrider,” meaning to unbridle, debridement is a method to remove the contaminants that will restrain wound healing and threaten life and limb.1 The level of energy and contamination seen in recent war trauma injuries places a heavy “bridle” on the wounded, necessitating both strict adherence to fundamental principles and novel techniques to best shed the restraints (Table 1).
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TABLE 1.: Debridement—Tips and Pearls
THE OVERALL TREATMENT PLAN
The immediate goals of saving life, preserving function, and minimizing complications are intimately tied to the individual patient, the specific injury, the current physiologic state, and the resources available. In austere settings, a surgeon may be treating host-nation civilians, foreign noncombatants, detainees, enemy combatants, or allied forces military personnel. The availability of evacuation to higher tiered treatment facilities, wound care supplies, specialized surgical care, rehabilitation, and prosthetics will define the goals of the initial treatment. In most cases, stabilizing the patient for transport and leaving options for the surgeons who will provide the definitive treatment entails debriding all devitalized tissue and contaminants and retaining all viable tissue for reconstruction. Limb salvage and the resources that may be entailed with making that initial decision can prove costly if in-country resources and capabilities are unable to sustain that course. If a limb is not salvageable, the availability of prosthetics can guide the decision of how much length the initial surgeon should retain. For example, an allied forces patient with planned medical evacuation to a developed nation with a modern health-care system may be well suited for a transtibial amputation, while the same injury in someone undergoing initial stabilization and following up in a less developed health system may be better served by a Chopart or Syme amputation if prosthetics will not be available.2
While early administration of appropriate antibiotics tailored to the type and severity of the wound cannot be overstated, devitalized tissue represents a bacterial and fungal feeding ground with compromised blood flow and thus limited access for antibiotics to contaminating organisms. Debridement, “cutting the reigns” of the infectious bridle to wound healing, is paramount.
INDICATIONS FOR DEBRIDEMENT
Deciding which wounds need debridement is an important part of triage. Generally, wounds that are caused by small fragments, leaving a punctate laceration or wound smaller than 2 cm without a fascial defect may not need formal surgical debridement. All wounds associated with fractures or traumatic arthrotomy or those penetrating the fascia, pleura, peritoneum, and vascular structures should be debrided.2 Even skin wounds smaller than 2 cm may be associated with extensive soft tissue injury beneath, and the energy involved must be considered. In the same way that some may consider any open femur fracture to be a Gustilo Type III soft tissue injury regardless of laceration size, punctate skin lesions in high-energy blast trauma may overlie a more extensive soft tissue injury below the surface of the skin. There are 4 effects of blast injuries which represent the most common mechanism of extremity injury in recent military campaigns. Of primary, secondary, tertiary, and quaternary blast effects, the majority of tissue damage is incurred secondarily, as penetrating trauma from irregularly shaped fragments tumble at up to 1800 m/s through soft tissues, decelerating rapidly and imparting kinetic energy to the patient's extremities.3 For comparison, one can consider the wounding characteristics of the AK-47 assault rifle, which propels a larger missile with a muzzle velocity approximately half that of smaller blast fragmentation. With kinetic energy imparted to the tissues being proportional to the square of velocity, energy conferred to tissue from small blast fragments entering through small lacerations can exceed the energy and imparted injury from high velocity rifles that propel more massive fragments and leave larger entry wounds. Consideration of the mechanism of injury is arguably just as important as laceration size and specific tissue involvement when soft tissue debridement is being contemplated.
CONSIDERATIONS FOR TIMING DEBRIDEMENT
Possibly the most vexing concerns when it comes to debridement are when and how frequently to do it. The principles of “damage control orthopaedics” dictate that there is a window of opportunity for stabilization before a second physiologic “hit” may be detrimental to a resuscitated trauma patient. In theatre, where high-energy wounds are constantly evolving and patients are being ushered to higher tiers of care, it may prove difficult to strictly adhere to these principles, especially as surgeons at the next facility take responsibility for wounds that they have not yet personally evaluated. In the same way that Friedrich in 1898 and Robson in 1973 presented widely accepted data that encouraged open fracture debridement within 6 hours of injury, a philosophy that has since been refuted based on clinical outcome data,4 the damage control philosophy represents a valuable set of tenants to be considered, but that may not be realistically extrapolated to universal surgical practice.
For example, an initial blast injury debridement may include assessment and treatment of vascular lesions proximal to the primary zone of injury, resulting in prolonged operative time and hypotension. The decision to preserve vascularity to some tissues while putting other tissue at risk may ultimately lead to more frequent debridements and continued physiologic “hits.” A surgeon can expect the evolving soft tissues to have a very different appearance, with additional tissue necrosis 24 hours after initial surgical intervention. Early use of vascular shunts along with careful consideration of definitive bypass timing must be closely weighed against duration and frequency of operative insults (see Fig. 1, Supplemental Digital Content 1, https://links.lww.com/BOT/A773).
In summary, intravenous antibiotics should be dosed immediately, and initial debridement should take place as soon as the patient is hemodynamically stable. Wounds that are not evaluated within 24 hours are likely to require more extensive and aggressive debridement.2 Conservative debridement and allowing tissue to “declare itself” is no longer recommended. Frequent “look-backs” every 24–48 hours may be necessary until the wound has been stabilized, with the timing and extent of debridements based on both early evaluations of the wound severity and the patient's baseline physiology. Within 72 hours of injury, wounds may need to be inspected surgically, as frequently as every 24 hours, and as the surgeon gains control of the soft tissue injury, the debridements can be further spaced. A final closure strategy should be delayed until the wound has been “stabilized,” defined by the presence of viable tissue and the absence of additional nonviable tissue.5
CONSIDERATIONS FOR EXTENT OF DEBRIDEMENT
There is no substitute for sharp surgical debridement. Early decisions are guided by vascular status of the limb, practicality of limb salvage, and the patient's physiologic status.
When the situation permits, it is recommended to sterilely prepare the entire limb, including a prehospital tourniquet and sites for proximal vascular access and control. For proximal thigh wounds or traumatic above-knee amputations, the abdomen should be included in the prep to allow for access to the common iliac vessels.6 Some situations may call for presurgical amputation of clearly nonviable extremities, that will only bring contamination into the field. Once sterilely prepped, and with hemostatic clamps and a sterile tourniquet available, the field tourniquet can be released and active hemorrhage controlled.
In mass casualty scenarios where multiple patients may have prehospital tourniquets applied, operative resources will be strained, resulting in prolonged warm ischemia times and excessive soft tissue necrosis. Tourniquets should be loosened early to mitigate ongoing tissue damage in patients awaiting operative debridement. Direct pressure, pressure dressings, vascular clips, and ligature should be used as adjuncts to limit ischemic injury. For example, an isolated vascular clamp or tie on a brachial artery laceration allows early reperfusion of the hand and forearm through collateral flow otherwise arrested by junctional tourniquets. When using these adjuncts, the tourniquet should still be maintained proximally in the event of bleed-through due to increased pulse pressure or loss of initial blood clot, that may occur during resuscitation.
Debridement should be performed in an organized sequence comfortable and familiar to the performing surgeon, in order to ensure that all foreign material and nonviable tissue have been excised. Here, the skin will be discussed first. The surgeon will need to extend the wound for exploration to define the involved tissue or the zone of injury, usually extending in-line with the long axis of the limb to maintain blood supply and incising obliquely across flexion creases to prevent contracture. The zone of injury is often more extensive than appreciated on the first look and will declare its margins on subsequent debridements, in some cases not truly elucidated until heterotopic ossification matures. Once exposed, debridement ensues with the removal of contaminants and nonviable tissue, keeping in mind that skin is resilient, and nonshredded skin flaps with a base to length ratio exceeding 1:2 could prove useful in definitive closure. “Skin traction,” in the form of 3–4 kg of weight anchored to a stockinette and stapled to the skin edges of an amputated extremity, or in the form of tensioned elastic vessel loops fixed by staples to the edge of an open wound, can help promote wound closure with healing by primary intention. Similarly, downsizing the sponge placed over a wound permits void contracture with negative-pressure therapy. Skin traction itself may prove valuable to preserving deeper tissue planes, as it can prevent soft tissue retraction and leave viable tissue available for reconstruction2 (see Fig. 2, Supplemental Digital Content 2, https://links.lww.com/BOT/A774).
Like nonviable skin, nonviable subcutaneous tissue, fascia, and muscle should be sharply excised, with complete fasciotomies when there is concern for the development of elevated intracompartmental pressures, and evaluation of each individual muscle belly within compartments where tissues are at risk. Muscle viability is classically indicated by the 4 “C's,” which may be unreliable during initial evaluation.7 “Color” is the least reliable of the 4, with sources of muscle discoloration including contamination, contusion, hematoma, vasoconstriction, desiccation, and dressing and local therapy effects, in addition to avascularity and nonviability. “Capacity to bleed” may likewise be clouded by transient vasoconstriction or by a small amount of falsely reassuring venous flow that does not truly represent viable end organ perfusion. “Consistency” and “Contractility,” the muscle's ability to rebound to its initial shape and contract after stimulus are the most reliable initial viability measures, which should be tested with a pinch of forceps instead of electrocautery, since the latter may prove overly sensitive and further devitalize the tissue that we seek to preserve.
Neurovascular structures that are left in continuity, even if apparently nonviable, are left intact and should be covered with viable muscle, fat, or skin, unless they are needed for arterial revascularization. After revascularization procedures, care should also be taken to cover the repairs and grafts biologically. Likewise, tendons should be preserved and covered. Vacuum-assisted devices should not be placed directly on exposed arteries, veins, nerves, or tendons.
Delivery of the bone ends is crucial to the adequate debridement of fracture edges and the canal in open fractures. Bone contamination in blast injuries may include intramedullary mud, shrapnel, and debris that tracks proximally creating a nidus for infection that is difficult to access and treat. Even during subsequent debridements, when external fixation is already in place, loosening the fixator to allow access to the medullary canal may be necessary if there is evidence or concern that contamination remains.
Bone fragments that lack periosteum or soft tissues attachments should be excised, with the exception of major articular fragments of salvaged joints. Traumatic arthrotomies require irrigation of the intra-articular space, with reapproximation of the capsule if tissue is available. Saline load testing and computed tomography can be used if there is a question in diagnosis.
IRRIGATION AND ADJUNCTS
After debridement, wounds should be irrigated with warm, sterile fluids, either through low-pressure flow through sterile tubing, such as cystoscopy tubing, or through low-pressure pulse irrigation systems or arthroscopy pumps. While soaps and antibiotic solutions may lower initial bacterial counts, normal saline under low-pressure flow or bulb suction irrigation demonstrates decreased rebound bacterial counts with less damage to native tissues and is currently the recommended method of irrigation.8–14 Recently, a very large multicentered clinical trial demonstrated that irrigating extremity open fractures with castile soap increased the infection rates (14.8 vs. 11.6% for castile soap and saline, respectively).15 In austere environments where sterile irrigate is not available, or not available in sufficient volumes, potable water can be substituted.16 Diluted Dakin's solution, initially used in World War I prior the advent of broadly used antibiotics, has returned to the surgeon's armory after falling out of favor for its cytotoxic affects. In dilutions of 0.0125% sodium hypochlorite, one tenth the original “quarter strength” Dakin's solution, antifungal and antibacterial properties may be preserved without causing cytotoxicity to host cells and is more effective than other antifungal agents such as mafenide acetate and amphotericin B, but this should only be reserved for wounds where there is a high index of suspicion17,18 (see Fig. 3, Supplemental Digital Content 3, https://links.lww.com/BOT/A775).
DRESSINGS AND CLOSURE
Traumatic contaminated wounds should not be closed primarily due to the risk of infection, but should be dressed under as sterile conditions as the environment permits. Negative-pressure wound therapy should be used between procedures and during transport or evacuation, lowering demands on personnel and physical resources necessary for wound care, while lowering infection risks and bacterial loads in tissue.19,20 Collection of pre- or post-debridement cultures is not correlated with timing of wound closure or infectious outcomes and is not routinely recommended.21
APPLICATIONS TO DISASTER AND INTENTIONAL VIOLENCE INJURIES
War offers an opportunity for military health-care providers struggling to address new challenges to make strides in patient care that we hope will transcend national borders and current conflicts. The lessons learned in debridement and irrigation of war wounds, largely incurred by improvised explosive device blasts in Iraq and Afghanistan, can be applied to high-energy injuries, industrial and natural disasters, and intentional violence that is seen at home managed by civilian physicians.
CONCLUSIONS
Debridement is an integral procedure in contaminated open orthopaedic trauma. Keeping the overall treatment plan and damage control principles in mind, thorough and repeated removal of contaminants and excision of evolving nonviable tissues should coincide with the following interventions: early intravenous antibiotics, control of bleeding, musculoskeletal stabilization with external fixation, and delayed wound closure with negative pressure wound therapy and skin traction. These therapies are supported by evidence and have been used for open blast injuries encountered in recent armed conflict. Implementation of these techniques and strategies has improved frontline care provided by military orthopaedic surgeons, and the lessons learned should be applied to similar injuries that may be encountered in disasters and intentional violence seen in both austere settings and in civilian centers going forward.
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