Acute compartment syndrome (ACS) is a well-known pathophysiologic complication of trauma or tissue ischemia. ACS affects the appearance, function, and even the viability of the involved limb, and demands immediate diagnosis and treatment. However, ACS is difficult to diagnose and the only effective treatment is decompressive surgical fasciotomy. The clinical signs and symptoms may easily be attributed to other aspects of the injury, which further complicates the diagnosis. This article highlights the latest information regarding the diagnosis of ACS, how to perform fasciotomies, how to manage fasciotomy wounds, and also reviews complications and outcomes of ACS.
Key points
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Frequent clinical assessment of patients considered to be at risk for developing compartment syndrome, ideally using a structured checklist, remains the cornerstone of diagnosis. In alert patients, monitoring of limb swelling, pain (both at rest and with passive muscle stretching), and neurologic status provides clues to the onset of acute compartment syndrome (ACS). The clinical findings are of greatest utility when several findings are present together.
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When a patient is unconscious or otherwise not able to be clinically assessed at frequent intervals, then continuous measurement of intramuscular pressure within the anterior compartment is of benefit. Continuous pressure monitoring, using a threshold for fasciotomy of a perfusion pressure (diastolic pressure minus muscle pressure) sustained at less than 30 mm Hg for 2 hours, has a 93% positive predictive value for the diagnosis of ACS.
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Although based primarily on retrospective studies, the literature is convincing that, when compartment syndrome is going to occur, early fasciotomy can avoid myonecrosis or ischemic neuropathy. However, the challenges in diagnosis, and the fact that compartment syndrome does not begin at a well-defined point in time, make it impossible to draw specific conclusions about the optimum timing of fasciotomy.
Introduction
Nature of the Problem
Acute compartment syndrome (ACS) is a complication of trauma or tissue ischemia, and can potentially involve any myofascial compartment in the body, whether in the extremities or trunk. Compartment syndrome most often occurs following a fracture or a crush injury to the limb. When muscle swelling occurs following such injury, or with muscle reperfusion following a period of ischemia, the mass within the myofascial compartment increases because of accumulation of blood and other tissue fluids. Because of the inelastic nature of muscle fascia and other connective tissues, this accumulation of mass leads to increased pressure within the compartment, which is transmitted to the thin-walled venous system, causing venous hypertension and further transudation of fluid. Progressive tissue ischemia and necrosis ensues, with eventual irreversible ischemic injury to all of the myoneural tissues within the involved compartment.
Despite ACS being well known and most clinicians being aware of its potential limb-threatening nature, it is a progressive phenomenon, and there is no standard definition of when compartment begins. The standard clinical signs and symptoms of ACS are pain and swelling, which are just as common in patients without ACS. It is possible to quantify intramuscular pressure by direct measurement, but both the clinical findings of ACS and measurement of intramuscular pressure have significant pitfalls as a means of diagnosis. As a result, there is significant variation in the diagnosis of ACS and the frequency with which fasciotomy is performed. Compartment syndrome is one of the most common causes of litigation against orthopedic surgeons.
The only effective treatment of ACS is immediate decompressive surgical fasciotomy, wherein the skin and muscle fascia of the involved compartment are incised the length of the compartment in order to release the constricting soft tissues and increase the volume of the muscle compartment, thereby causing immediate reduction of compartment pressure and restoring perfusion. It has been estimated that muscle necrosis may occur within 2 hours of injury in as many as 35% of patients with ACS. It is widely considered that performing early fasciotomy is critical to achieving the best possible outcomes when compartment syndrome occurs, and it is generally accepted that performing unnecessary fasciotomy is better than missing a true case of compartment syndrome.
Introduction
Nature of the Problem
Acute compartment syndrome (ACS) is a complication of trauma or tissue ischemia, and can potentially involve any myofascial compartment in the body, whether in the extremities or trunk. Compartment syndrome most often occurs following a fracture or a crush injury to the limb. When muscle swelling occurs following such injury, or with muscle reperfusion following a period of ischemia, the mass within the myofascial compartment increases because of accumulation of blood and other tissue fluids. Because of the inelastic nature of muscle fascia and other connective tissues, this accumulation of mass leads to increased pressure within the compartment, which is transmitted to the thin-walled venous system, causing venous hypertension and further transudation of fluid. Progressive tissue ischemia and necrosis ensues, with eventual irreversible ischemic injury to all of the myoneural tissues within the involved compartment.
Despite ACS being well known and most clinicians being aware of its potential limb-threatening nature, it is a progressive phenomenon, and there is no standard definition of when compartment begins. The standard clinical signs and symptoms of ACS are pain and swelling, which are just as common in patients without ACS. It is possible to quantify intramuscular pressure by direct measurement, but both the clinical findings of ACS and measurement of intramuscular pressure have significant pitfalls as a means of diagnosis. As a result, there is significant variation in the diagnosis of ACS and the frequency with which fasciotomy is performed. Compartment syndrome is one of the most common causes of litigation against orthopedic surgeons.
The only effective treatment of ACS is immediate decompressive surgical fasciotomy, wherein the skin and muscle fascia of the involved compartment are incised the length of the compartment in order to release the constricting soft tissues and increase the volume of the muscle compartment, thereby causing immediate reduction of compartment pressure and restoring perfusion. It has been estimated that muscle necrosis may occur within 2 hours of injury in as many as 35% of patients with ACS. It is widely considered that performing early fasciotomy is critical to achieving the best possible outcomes when compartment syndrome occurs, and it is generally accepted that performing unnecessary fasciotomy is better than missing a true case of compartment syndrome.
Indications/contraindications for emergency fasciotomy
The only effective treatment of ACS is immediate fasciotomy, but if fasciotomy is performed the patient is committed to further surgery, a prolonged hospital stay, increased cost of care, and increased morbidity. Thus, clinicians facing patients at risk of ACS must choose a treatment plan from among several bad choices: perform fasciotomy and expose the patient to the risks and costs associated with that procedure, or not do fasciotomy and expose the patient to the potential adverse effects of delayed fasciotomy or missed ACS. Because of the latter, the primary indication for fasciotomy is a reasonable clinical assessment that the patient’s examination is deteriorating, or that the patient is at risk of ACS and cannot be reliable followed from a clinical perspective.
Given that the diagnostic stakes are high and that there is some uncertainty in the diagnosis of ACS, understanding the risk factors for compartment syndrome allows surgeons to raise or lower the threshold for fasciotomy in a given clinical scenario. Young men sustaining high-energy trauma, especially of the lower leg and forearm, are considered to be the most at risk for compartment syndrome, and a recent analysis suggests that young age is the strongest predictor. ACS can occur without fracture, and such patients are older and have more medical comorbidities than those with a fracture. Fracture pattern and location are also important. Park and colleagues evaluated 414 acute tibial fractures and compared rate of ACS requiring fasciotomy according to fracture location. ACS was most common in mid-diaphyseal tibia fractures (8% of cases), compared with proximal and distal metaphyseal fractures (<2% each). Several series report an appreciable incidence of compartment syndrome in patients with tibial plateau fractures, and these fractures must also be considered in the high-risk category. In addition, ACS occurs in slightly more than half (53%) of patients with medial knee fracture-dislocations and 18% of patients with bicondylar tibial plateau fractures treated with knee-spanning external fixation.
The indication for fasciotomy is the diagnosis of early or impending ACS, but ACS is an entity without a definitive diagnostic test. The clinical diagnosis of ACS is best made using specific clinical findings ( Box 1 ). However, the published literature makes it clear that these clinical signs and symptoms are unreliable, whether they are present or absent.
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Tenseness or firmness of the involved compartment.
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Motor weakness.
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Pain with passive stretch of the involved muscle.
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Increasing pain and pain that is out-of-proportion to that expected.
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Loss of sensation in a specific neuronal distribution for a given compartment (eg, the deep peroneal nerve for the anterior compartment of the leg).
Given the lack of diagnostic certainty assigned to clinical signs and symptoms, it makes sense to use objective evidence to diagnose ACS and decide when fasciotomy is needed. Compartment pressure monitoring has been advocated since the 1970s, but the literature has not been able to provide consensus recommendations on what pressure thresholds were best used for fasciotomy. The use of a pressure threshold for fasciotomy that is based on muscle perfusion pressure rather than on an absolute value of muscle pressure is more relevant physiologically and more specific. The perfusion pressure (also referred to as the delta P) is defined as the difference between the patient’s diastolic blood pressure and the intracompartment pressure. Fasciotomy may be safely avoided as long as the perfusion pressure remains greater than 30 mm Hg. Typically, the anterior compartment is monitored because the pressures within it are typically highest.
In the past, measurement of muscle pressure has been considered most valuable in patients who cannot be evaluated clinically, or have equivocal findings. Single pressure measurements alone are not representative of temporal changes in muscle pressure, and serial or continuous measurements showing increasing muscle pressure or decreasing perfusion pressure are likely to be more specific for patients who have compartment syndrome. Routine continuous pressure monitoring has been shown to dramatically reduce the rate of fasciotomy while avoiding cases with evidence of missed ACS. Janzing and Broos warned that routine use of continuous compartment pressure monitoring may increase the rate of fasciotomy, and the literature suggests that the overall rate of fasciotomy is higher when continuous pressure monitoring is used compared with other methods.
McQueen and colleagues, in Edinburgh, who published the original data advocating the use of continuous pressure monitoring, recently reported the sensitivity and specificity of continuous monitoring. Using a threshold for fasciotomy of a perfusion pressure sustained at less than 30 mm Hg for 2 hours or more, the calculated sensitivity of this method is 94%. This sensitivity is far better than any single clinic examination finding, and establishes this technique as the best objective indication of the need for fasciotomy.
There are some pitfalls associated with the use of pressure measurements for decision making regarding fasciotomy in patients suspected of ACS. First, there is spatial variation in the pressure within a given compartment, with pressures highest within 5 cm of the fracture and more centrally in the muscle. However, there is no consensus on whether clinicians should obtain pressures near the fracture to obtain the highest pressure, or measure further away from the fracture to obtain a pressure that may be more representative of most of the compartment. Second, there is error in the measurement, highlighted by a recent cadaveric study. Using a standardized cadaver model of extremity compartment syndrome and a commercially available pressure monitor, 38 physicians were asked to measure intracompartment pressure. Correct technique was only used 31% of the time, and 30% of the measurements were associated with a “catastrophic” error. Furthermore, even when the correct technique was used, only 60% of the measurements made were accurate, with even greater inaccuracy when proper technique was not used. Clinicians evaluating patients for ACS should be aware of these potential errors in the measurement of compartment pressures.
Another source of uncertainty in the determination of delta P is choosing what blood pressure value to use, especially if the patient is under general anesthesia. Kakar and colleagues evaluated 242 patients undergoing tibial nailing, recording preoperative, intraoperative, and postoperative blood pressures. During surgery, there was a statistically significant decrease in diastolic blood pressure compared with preoperative values (average decrease, 18 mm Hg), whereas postoperative diastolic pressure was within 2 mm Hg of the preoperative value. Thus, use of intraoperative blood pressure measurements for calculation of perfusion pressure may give a spuriously low perfusion pressure and lead to unnecessary fasciotomy. These investigators recommend using preoperative blood pressure values to calculate perfusion pressure when patients are under general anesthesia, except when the patient is going to remain under anesthesia for several more hours.
The presence of a known coagulopathy represents one of the only clear contraindications to fasciotomy, when doing a fasciotomy might cause exsanguination of the patient. A relative contraindication to fasciotomy is the late diagnosis of ACS, when muscle necrosis is already present. However, there are no validated methods to determine when it is too late, and substantial clinical experience is needed to make such a decision. In such settings, it is extremely important to document the history, examination findings, and the clinical reasoning that led to the choice to avoid fasciotomy in a given circumstance.
Surgical technique: decompressive fasciotomy
Decompressive fasciotomies must be done using 1 or more generous skin incisions with release of all constricting fascia within the involved muscle compartment. The specific locations of the incisions to be made and the anatomic structures that require release vary depending on the involved compartment. Fasciotomies must include an adequate skin incision in addition to the fascial release.
Double-incision Leg Fasciotomy
Fasciotomy of the 4 compartments of the lower leg is most safely done using 2 incisions: 1 medial and 1 lateral. The deep posterior compartment of the leg is released from the medial incision, whereas the lateral incision is used to decompress the anterior and lateral compartments. The superficial posterior compartment may be released from either incision. When the dual-incision technique is used, the intervening skin flap may be in jeopardy if there has been damage to the anterior tibial artery. If an anterior tibial artery injury is recognized before surgery, a single-incision 4-compartment release may be more appropriate (discussed later).
The lateral incision is made 2 to 3 cm lateral to the crest of the tibia ( Fig. 1 ). Skin flaps are elevated by sharp dissection anteriorly and posteriorly, exposing the fascia of the anterior and lateral compartments. The lateral compartment fascia over the peroneal muscles is released. The lateral intermuscular septum that divides the anterior and lateral compartments and the superficial peroneal nerve are identified. In addition, the fascia over the anterior compartment is completely released. Alternatively, the fascia overlying the lateral compartment can be released followed by division of the intermuscular septum to decompress the anterior compartment. However, injury to the superficial peroneal nerve may be more likely with this technique.
