5 Preoperative assessment and classification of soft-tissue injuries
5.1 Preoperative assessment of soft-tissue injuries
Authors Farid Rezaeian, Reto Wettstein, Dominique Erni, Yves Harder
5.1.1 Basic principles of assessment
Examination of wounds, soft-tissue defects, and concomitant injuries in orthopaedic trauma is based on a systematic survey that must be performed in a standardized manner in order to assess the injury correctly (chapter 6.1). A detailed case history goes hand in hand with clinical, laboratory, and radiographic evaluation—everything aimed at rapidly obtaining a diagnosis that is as accurate as possible. History and assessment must be surveyed and recorded immediately. However, emergency measures that are not directly related to the soft-tissue injury may sometimes delay assessment, for example, in a polytraumatized patient. Furthermore, the evaluation of an unconscious patient requires laboratory and radiographic support, or even deferral of the examination. The value of the assessment of injured soft tissues and the classification of their severity greatly depends on the examiner′s experience (chapter 5.2). The most experienced surgeon in house should, therefore, be the one to assess the patient. If the diagnostic procedure is delegated or performed by a junior physician on call, he or she must be in close contact with the consulting specialist. A systematic examination of the patient in general and of the injury in particular will allow the surgeon to be thorough and efficient. This is a prerequisite for appropriate subsequent decision making and preoperative planning. Moreover, initial and definitive treatment options, including reconstructive needs, as well as the coordination with all the team members involved, must be taken into consideration (chapter 6.2). Regardless of their extent, th e assessment of soft-tissue injuries must address the medical history as well as the following clinical issues:
factors affecting the general condition of the patient (eg, age, gender, vascular diseases, diabetes, drugs, nicotine, alcohol, tetanus immunization, or infection with HIV, hepatitis B or C)
mechanism and energy of injury
agent that caused the wound
time of injury
localization, size, extent, and character of the wound (eg, crush, abrasion, defect, degloving)
wound contamination or presence of foreign bodies
involvement of surrounding structures (eg, nerves, vessels, muscles, tendons, bone, cartilage, or any combination of these).
Several systems for the classification of traumatized soft tissues are in clinical use such as the Gustilo-Anderson classification [1, 2], the AO soft-tissue classification [3], and the Hanover fracture scale [4, 5] (chapter 5.2). The following description will explain in detail some of the already mentioned general statements on the history of the injury as well as the clinical and nonclinical (ie, laboratory and radiographic) assessment.
5.1.2 Assessment of trauma history
Knowledge about the mechanism and the involved energy of an injury will help to judge the severity of the resulting lesions. It will also influence the therapeutic approach and subsequent decisions ( Fig 5.1-1a–b ). This information may roughly indicate the extent of the zone of injury (chapter 10.3.3), the potential capacity for wound healing and the possible extent of contamination. In addition, it will also supply an estimate of the risk of complications and functional damage [6]. Superficial abrasions, simple cuts, and low-energy injuries that heal by secondary intention or simple primary wound closure will be classified and approached differently compared to high-energy crush injuries, deep, multistructural soft-tissue defects, or extensive degloving as well as severely contaminated wounds or farming injuries (chapter 5.2).
Furthermore, it is of utmost importance to include the patient′s age and associated comorbidities in the assessment, because senescence [7], diabetes [8], or smoking [9, 10] may not only affect wound-healing capacity, but may even be associated with decreased survival rates in polytraumatized patients.
Treatment of infected wounds and soft-tissue defects with associated injuries to tendons, muscles, blood vessels, nerves, or bone should be addressed rather aggressively. Definite assessment of the local soft-tissue injury can sometimes only be performed during emergency irrigation and debridement, or even after repeated debridement (chapter 6.1, 7.1, 7.2). Once an assessment has been carried out, closure of the defect not only depends on the condition of the adjacent tissues, but also on the general status of the patient, the availability, experience, and skills of the surgeon in charge and the whole team in the operating room.
5.1.3 Clinical assessment of injury and tissue viability
Clinical examination must be performed on the undressed patient under sterile conditions both of the injured area (sterile drapes) and the examiner (sterile gloves, face mask, etc) using an adequate light source. Often, full assessment of the extent of soft-tissue injury can only be carried out in the operating room. Room temperature is indicated for the assessment of the soft-tissue injuries in order to minimize temperature-induced changes of the skin′s perfusion that could influence the assessment. Exact localization, type (ie, clean, dirty, contaminated, infected), and extension of the injury as well as involved neighboring structures must be recorded, documented, and photographed (chapter 5.1.5). Traumatized soft tissues must be compared with adjacent healthy tissues. General anesthesia is recommended for more extensive injuries, especially if they are associated with single or multiple fractures.
Severe soft-tissue injury not only involves skin and subcutaneous tissue, but also muscles, tendons, nerves, vessels and/or bone ( Fig 5.1-2a–b ). In practice, soft-tissue assessment is performed from superficial to deep layers, starting out with the skin. With some experience, examination of the skin allows a relatively good appraisal of perfusion that can be obtained by examination of color, capillary refill, turgescence, and surface temperature. It is recommended to always use a reference area for comparison. Differences in skin temperature of as little as 1°C can be perceived from the dorsum of the hand. Assessing perfusion by skin color may not be practical in the absence of an adequate light source, or in heavily pigmented or very pale skin. In addition, venous stasis may be mimicked by bruising due to trauma and/or intradermal hemorrhage. Capillary refill is examined by applying light pressure on the skin with a finger or instrument, which is then quickly released ( Fig 5.1-3a–c ). Scarification of the skin with a sharp needle or a scalpel may sometimes be helpful in order to judge capillary bleeding. Adequate perfusion is then validated by judging color (eg, light or dark red) and flow of the capillary bleeding. Absent capillary bleeding is suggestive of nonviable tissue. Nevertheless, skin may reperfuse after trauma. Accordingly, the assessment must not only include the time interval since and mechanism of the trauma, but also skin color. Bluish discoloration will indicate some injury to the skin, which it may survive, whereas greyish discoloration of the skin will indicate changes beyond the skin′s ischemic tolerance. All these clinical signs should be used in order to assess perfusion of normal skin or of a flap ( Table 5.1-1 ). In contrast, muscle viability may be determined by assessing the four “C”s: color, contractility by mechanical or electrical stimulation, consistency, and the capacity of the muscle to bleed. Absent pulses may suggest a severely injured artery proximal to the region of interest. The presence of a pulse more distally does not guarantee intact vascularity, because retrograde perfusion of the injured vessel may maintain a palpable pulse through collateral vessels. Therefore, clinical examination must include palpation of the respective vessel, using the finger to occlude flow proximal to the supposedly injured vessel.
In case a wound is situated over a tendon, the examination should include testing the tendon′s function actively and passively. If in doubt, wound exploration must be carried out in the operating room and the surgeon must be prepared to repair the tendon at that time. The viability of a tendon cannot be judged in a freshly injured patient. Necrotic tendons, however, that were exposed over a period of days, will macerate and develop a greenish discoloration.
Axial malalignment of the limb and crepitation are typical for a fractured bone, which must be verified by radiography (see below).
The following clinical signs may indicate significant injury to nerves and must be assessed immediately:
severe pain and dysesthesia resulting from acute swelling of a limb, respectively compression of a nerve (eg, compartment syndrome)
massive contusion or transection of a nerve resulting in paralysis and functional deficit of a limb, foot, or hand, eg, drop foot (deep fibular nerve), wrist drop (radial nerve), claw hand (ulnar nerve), monkey hand (median nerve), or traumatic paresis of the brachial plexus
absence of two-point discrimination (ie, ability to discern that two nearby sharp objects touching the skin are felt as two distinct points)
lack of response to strong and painful stimuli and absence of peripheral reflexes.
5.1.4 Nonclinical assessment of injury and tissue viability
Full assessment of a soft-tissue injury often requires further investigations using various devices. Several techniques are available to assess the viability of skin ( Tab 5.1-2 ).
Indirect variables
Temperature measurement
Temperature measurement for the assessment of tissue perfusion of soft tissues, including flaps, depends on several factors that must be fulfilled:
exposure of the patient to room temperature in order to avoid errors caused by external heating or cooling by convection
reference measurement of normal skin in the vicinity of the tissue under investigation
continuous registration of temperature for comparison
repeated measurements at exactly the same spot
suitable and reliable instruments such as a temperature probe that can be fixed to the skin, an ear thermometer, or an adhesive thermometer.
If the above prerequisites are fulfilled, temperature measurement is easy to handle and a reliable method in order to monitor skin or flap perfusion. However, such options may not always be available as in cases of buried flaps or in very small flaps surrounded by well-vascularized tissue. Note that the surrounding temperature of the tissue is able to maintain an adequate temperature of the flap even despite inadequate perfusion, which can be misleading.
Tissue oxygenation
Tissue oxygenation can either be assessed by measuring partial oxygen tension or oxygen saturation of the tissues. Both are determined by the difference between oxygen delivery and consumption, the former being defined as the product of blood flow and arterial oxygen content. The value obtained with partial oxygen tension measurement reflects the oxygenation value in the surrounding intercellular space. The value for oxygen saturation, however, is mainly determined by the venous blood pool in the area under investigation, which is the major contributor to the total number of hemoglobin molecules present in this tissue volume. Partial oxygen tension may easily be assessed on the tissue′s surface or within the tissue using Clark type microprobes (polarographic electrodes inside of an oxygensensitive microcell) or fiber-optic microprobes measuring partial oxygen pressure (pO2) by fluorescence quenching of a dye. Oxygen saturation is usually measured with whitelight spectrometry or near-infrared spectrometry [11]. Provided that arterial oxygen content and oxygen consumption are constant, partial oxygen tension and oxygen saturation can be used to assess blood flow, especially in areas of the body that are difficult to reach (eg, buried flaps). However, malpositioning of the probe or temperature-dependent changes in blood flow may bias the true values of tissue oxygenation.
Invasiveness | Reliability | Quantification | Ease of handling | |
Temperature | No | Some | Some | Yes |
Tissue oxygenation | Yes | Yes | Yes | Some |
Acoustic Doppler | No | Some | No | Yes |
Laser Doppler flowmetry | No | Some | Some | Some |
Duplex, color Doppler | No | Yes | Yes | No |
CT imaging | Yes | Yes | No | No |
Fluorescent dyes | Yes | Yes | Some | No |
Fluorescent dyes
The perfusion of a skin area may be visualized by injecting a fluorescent dye, ie, indocyanine green. The light emission induced by excitation with a laser light can be recorded by a video camera equipped with a filter corresponding to the wavelength of the emitted light. The fluorescence intensity is quantified in terms of assessing the increase of intensity after dye injection [12]. The technique may reflect the perfusion of large skin surfaces. However, injection of fluorescent dyes in order to detect the extent to which skin or muscle is perfused is an invasive technique. Moreover, it may lead to false results in acute settings due to reactive vasoconstriction or centralization of the blood flow as experienced in severely injured patients suffering from significant blood loss or hypothermia.
Direct variables
Radiological imaging
Whereas conventional angiography is still the method of choice to visualize patency and particularly intraluminal characteristics of peripheral arteries, new technologies based on magnetic resonance (MR) or computed tomography (CT) have evolved. They allow for detailed imaging with accurate 3-D reconstruction of the arborization, the diameter, and the putative interruption of arteries and/or veins of less than 1 mm in diameter, including their course through the surrounding tissues [13]. In many institutions, conventional angiography has been substituted by CT angiography, generally using up to 64-slice scanning, made possible by the introduction of multidetector row scanners. In case of trauma involving an extremity, CT may also represent an excellent tool in order to assess the geometry of complex fractures, usually involving joints. Multi-slice CT—used conventionally or as a CT angiography—offers high accuracy, low cost and low inter-observer variability, particularly, if the recorded images undergo 3-D reconstruction of the designated anatomical region. In some cases, contraindications include claustrophobia, intolerance to the contrast medium and, to some extent, radiation load. The latter may be overcome with high-resolution MR angiography in the near future. MR tomography, and particularly MR angiography, provides very precise images of the soft tissues (ie, muscles, tendons, menisci, nerves, and vessels) without radiation, especially if 3-D reconstruction is involved. However, data acquisition is still very time consuming, expensive, and cumbersome for a traumatized patient. It cannot provide the essential information for soft-tissue damage in orthopaedic trauma, particularly in emergency situations.
Conventional angiography, although it is by far the most invasive radiological tool for vascular mapping, still represents a good backup tool whenever intraoperative assessment of a putative vascular lesion is required.
Plain x-rays of the injured area still constitute the gold standard for the radiological examination of orthopaedic trauma and, therefore, are mandatory. These x-rays should be obtained in two different planes during initial patient evaluation. Exceptionally, one x-ray plane may give sufficient information for primary diagnostics in cases of severely comminuted fractures or total or subtotal amputations. The x-ray is primarily intended to exclude or confirm, a fracture, as well as to define its type and complexity. Sometimes, the x-ray may even indicate the presence and severity of any associated damage to be expected. Beside the bone structures, special attention should be given to inclusion of air, radio-opaque shadows, or foreign bodies within the soft tissues.
Methods based on the Doppler effect
This effect, named after Christian Andreas Doppler, who first described it in 1842, is defined as the change in wavelength that occurs if the source of the wave and the recipient move in relation to each other. In medicine, this effect is applied by measuring the shift of the wavelength of an optical or acoustic signal caused by moving particles, eg, blood cells.
Acoustic Doppler velocimetry
An ultrasonic acoustic burst is emitted towards a vessel, where the particles moving within its lumen cause a shift in frequency and phase of the emitted sound, which is proportional to the velocity of the particles. These phase and frequency shifts are recorded and transduced either into an acoustic or a visual signal that reflect the flow velocity of the red blood cells. If diameter measurement is included, volumetric blood flow can be calculated and visualized (color Doppler or Duplex Doppler), whereas the acoustic Doppler is usually used to localize a vessel or to prove its patency, allowing for the discrimination between an artery and a vein. The method allows assessing vessels as small as 1 mm in diameter ( Fig 5.1-4a–b ).
In addition to vascular mapping, ultrasound may easily detect soft-tissue swelling caused by hematoma or seroma formation as well as significant lesions to tendons (eg, rupture of the rotator cuff or the patellar tendon, or the Stener lesion of the thumb). Muscles and foreign bodies that are not radio-opaque may also be visualized.
Laser Doppler flowmetry (LDF)
Laser Doppler flowmetry uses laser light, which is emitted towards a tissue surface [14]. The light penetrates the tissue to a depth of about 1 mm, where its wavelength is shifted by all particles moving within the sampled tissue volume. The extent of the shift correlates with the speed of the particles, and the sum of shifted laser light corresponds to the amount of moving particles, which allows calculation of volumetric blood flow within the sampled tissue area. The data are expressed in virtual perfusion units (PU), which only allow the assessment of relative, time-dependent changes. In addition, the interpretation of the values is complicated due to the phenomenon that an LDF signal may still be obtained by movement of artifacts, even in case of total ischemia (biological zero). Furthermore, the conventional application of LDF is restricted to an area of 1 mm2, whereas new scanning technologies allow blood-flow mapping of larger surface areas ( Fig 5.1-5a–c ).
Which method to use?
Multi-slice CT angiography has become the most reliable tool for vascular mapping. Acoustic Doppler is the cheapest, most easily applicable method in order to spot upstream and downstream vascular structures and to assess their patency. For their further characterization and blood-flow quantification, Duplex Doppler or color Doppler is required. Clinical evaluation by an experienced examiner provides a good estimate of tissue perfusion even in the operating room, except for muscle tissue or pigmented skin. The techniques based on ultrasonic waves are noninvasive and easy to apply. However, they are often very time consuming and investigator dependent.
Temperature and laser Doppler flowmetry monitoring are easy to handle and can therefore be used to monitor time-dependent changes. Yet, the validity of both methods may be jeopardized by external factors (ambient temperature, light) that may lead to artifacts and misinterpretation of the data. The same holds true for the measurement of tissue oxygen saturation, whereas partial oxygen tension provides the most useful information on tissue oxygenation. The drawback of this method as well as the fluorescent dye method is their invasiveness. The pros and cons of each method are summarized in Table 5.1-2 . All in all, some of the above mentioned techniques are not used on a regular basis in the acute setting, because they will not provide vital information for the therapeutical decision making right after trauma. However, they may be very useful in the follow-up surveillance of selected cases with damaged skin and muscle or with flaps.
5.1.5 Documentation of the injury
All findings and diagnoses identified during the primary survey in the emergency department (ED) should be recorded in detail and documented on the patient′s chart. For fractures and especially for soft-tissue injuries, a simple drawing of the injury, its location and extent is very helpful. Photographic documentation of the soft-tissue injury is a necessity for the consulting specialists, further planning and decision making as well as for follow-up, scientific, or legal reasons. Sometimes photographs may also keep too many people from wanting to inspect the injured area, which would otherwise greatly increase the risk of infection. Unfortunately, photographic documentation is often forgotten or not performed in sufficient quality. For a good documentation, a digital pocket camera with sufficient resolution is recommended. Overviews of the injury are important, but close-ups are needed to supplement the overview with details. The injured area is best presented on a clean, sterile cloth. Gross contamination and blood clots should first be removed. Direct flashlight is preferred to room light or operating room light. Photographs must carry the date of exposure and always be assignable to the patient. They are best stored with the operating room report, with copies for the surgeon in charge. For common understanding, the injury then has to be documented, using an appropriate classification system with acceptable reliability, and consequences for the treatment as well as for the prognosis, knowing that all fractures involve some degree of soft-tissue injury (chapter 5.2).
5.2 Classification systems
David A Volgas
5.2.1 Overview
All classification systems are designed to highlight similarities or differences between individual injuries. By grouping patients with comparable injuries, sufficient numbers of patients with such injuries may be studied in order to determine outcomes. This information may then be used to guide the treatment of individual patients with similar injuries. Unfortunately, soft-tissue injuries are even more diverse than fractures. While the x-rays of a fracture usually provide hard, reproducible, and objective facts, descriptions of soft-tissue injuries depend on rather subjective judgment, allowing different interpretations even in the presence of initial photographic documentation of the injury. Moreover, the extent of the injury may change dramatically following the development of necrosis and repeated debridement procedures. Therefore, numerous classification systems exist, which are based on anatomical and/or physiological observations. Some are limited to the injured part or even limited to specific types of injury, while others include systemic factors of the patient. All depend on the personal experience of the surgeon, and some may be appropriate in clinical settings while others in research.
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