Chronic exertional compartment syndrome

INTRODUCTION — Chronic exertional compartment syndrome (CECS) is a condition that typically affects young endurance athletes, especially those who run extensively. Like acute compartment syndrome (ACS), it is thought to result from increased pressure within a muscle compartment. CECS occurs primarily in the lower leg, although it has been reported in the forearm and elsewhere [1].

The presentation, diagnosis, and management of CECS are reviewed here. ACS and running injuries are discussed separately. (See "Acute compartment syndrome of the extremities" and "Running injuries of the lower extremities: Risk factors and prevention".)

DEFINITION AND PATHOPHYSIOLOGY — Acute compartment syndrome (ACS) occurs when increased intramuscular pressure (ie, hydrostatic pressure within the interstitial space of a skeletal muscle) impedes local tissue perfusion, leading to pain, paresthesias, and ultimately, compromised muscle function in the affected limb(s) [2,3]. Most cases of ACS are caused by trauma. Chronic exertional compartment syndrome (CECS) is a reversible form of ACS triggered by physical activity. Symptoms typically resolve quickly once exercise is terminated. As CECS is an episodic condition and compartment tissues are normal at rest, some refer to the condition simply as exertional compartment syndrome. (See "Acute compartment syndrome of the extremities" and 'Clinical features' below.)

The pathophysiology of CECS is not completely understood [4-6]. One theory is that tissue ischemia in CECS stems from a noncompliant fascial compartment that cannot accommodate the expansion of muscle volume that occurs with exercise. Simply put, "stiff" fascia does not allow for the increased blood flow that exercising muscle requires. As pressure increases and local tissue perfusion becomes compromised, metabolic demands cannot be met and ischemic symptoms develop. Several studies have demonstrated decreased blood flow and oxygenation in the legs of symptomatic patients with CECS [7-10].

The role of thicker or stiffer fascia is supported by some studies [11,12] but refuted by others [13]. However, neither macroscopic nor microscopic assessment of fascial thickness or stiffness has been shown to be a useful predictor of success following fasciotomy.

Exercise substantially increases blood flow to active muscles, causing their volume to expand by as much as 20 percent. Lower extremity intramuscular pressure can exceed 500 mmHg during contractions [14,15]. Perfusion of peripheral muscle occurs when the muscle is relaxed and the arterial-venous gradient is relatively high. The gradient must be at least 30 mmHg to overcome intramuscular resting pressure; if the gradient falls below this threshold, perfusion is compromised. A definitive diagnosis of CECS requires the measurement of elevated compartment pressures. (See 'Compartment pressure measurement' below.)

If significant tissue damage is sustained from prolonged or severe ischemia, the subsequent inflammatory cascade and swelling may prevent the typical normalization of pressures and resolution of symptoms that are expected from rest. In this way, CECS may rarely become an escalating syndrome that more closely resembles acute or traumatic compartment syndrome. This surgical emergency is discussed separately. (See "Acute compartment syndrome of the extremities".)

In addition to the pathologic effects described above, compromised perfusion and the resulting deoxygenation of muscle causes increased cell permeability, leading to a shift of fluid into the interstitial space. The fluid extravasation and potential metabolite accumulation may contribute to neural compression, exacerbating the pain experienced during activity, and may cause irreversible damage if left untreated [16].

EPIDEMIOLOGY AND RISK FACTORS — The true prevalence of CECS in the general population is unknown [17]. It is likely that many people suffering from early symptoms of CECS decrease or modify their activity level to manage their condition and never seek medical attention. In addition, CECS is likely under-diagnosed by the coaches, athletic trainers, and primary care physicians to whom symptoms are first presented [18]. The gold standard for diagnosis requires invasive pressure measurements in the affected muscle compartment, something rarely done in training rooms or primary care clinics. (See 'Compartment pressure measurement' below.)

Observational studies provide some sense of the prevalence of CECS among certain populations:

●A retrospective study of active Unites States military personnel reported 4100 cases of CECS between 2006 and 2011, for an incidence rate of 0.49 cases per 1000 person-years [19]. Age was the most significant risk factor, with the adjusted incidence ratio for personnel over 40 years almost nine times that of personnel under 20 years (IRR 8.77; 95% CI 7.31-10.52).

●A retrospective review of 226 patients (393 leg compartment pressure tests), of whom 153 were diagnosed with CECS, reported that 67 percent of the patients who gave a history consistent with the diagnosis were found to have elevated intramuscular pressure [20].

●In a retrospective study of 108 patients with lower leg pain of unknown cause, elevated intracompartmental pressures were found in 15 patients (13.9 percent) [21].

●In retrospective observational studies of patients with suspected CECS referred to specialty clinics and diagnosed by compartment pressure measurement, the reported incidence ranged from 28 percent in a study of 80 patients to 82 percent in a study of 276 patients [18,22,23].

Most published reports of CECS describe the diagnosis in athletes, particularly runners, with vigorous training regimens [22,23]. In one of the largest retrospective studies of CECS in a non-military population, 92.2 percent of affected individuals reported participation in sports [20]. The most common individual sport was running, while the most common team sports were soccer, lacrosse, and field hockey. Competitive athletes (63.1 percent) were more likely to have the condition compared to recreational athletes. These findings are consistent with another retrospective study of patients with CECS, which found the most common sports associated with the condition to be running (25 percent), soccer (23 percent), and field hockey (12 percent), while 50 percent of patients were multisport athletes [24].

CECS generally occurs in the leg [1], most often in the anterior compartment, followed in decreasing order of occurrence by the lateral, deep posterior, and superficial posterior compartments [18,25-27]. However, cases of CECS have been described in non-athletes and compartments of the foot, thigh, forearm, and hand [28-34]. CECS involving the upper extremity is rare, but may occur in participants of motocross or rowing. More rarely, CECS of the forearm has been reported in other forearm dominant sports, such as weight lifting, pitching, kayaking, and swimming [35-38].

Early studies of CECS were dominated by adult male patients and a large proportion of military recruits [24,26,39,40]. Studies involving older adults (mean age 26.6 years) suggest the condition occurs more frequently in males [27]. However, the condition occurs in both males and females, and studies of younger athletes suggest a female predominance. In one retrospective series of 155 patients treated surgically for CECS (mean age 16.4), 88 percent were female [24], while another series involving 153 confirmed cases (mean age 24), reported that 60 percent were female [20].

It is difficult to draw conclusions about factors that contribute to CECS because the condition is often misdiagnosed initially and there may be a delay of months or even years between the onset of symptoms and definitive diagnosis. In one series, patients suffered symptoms for an average of 28 months (range 1 to 144 months) before diagnosis [20]. Anecdotal evidence suggests that sudden increases in training volume may contribute, but such claims are susceptible to recall bias. Body mass index (BMI) does not seem to be a predictive factor. In one review, the average BMI was 25 and no difference was noted between patients whose muscle compartment pressures were sufficiently elevated to be diagnosed as CECS and those that were not [20]. Some experienced clinicians have found that patients with highly muscular calves are more susceptible to CECS, but there is no high-quality evidence to support this belief.

CLINICAL FEATURES — The typical patient with CECS is a young athlete, often a runner, who describes gradually increasing pain in a specific muscle region (usually the lower leg) during physical exertion (figure 1 and figure 2) [5,18,20,21,41-43]. The pain may be described as aching, squeezing, cramping, tightness, or pressure. Patients with CECS are typically asymptomatic at rest and during activities of daily living.

Reproducibility is among the most distinctive clinical characteristics of CECS. Pain typically begins within several minutes of starting the inciting activity, often at a specific point in training that patients recognize. As an example, runners often can describe the time or distance required for symptoms to develop. Pain steadily increases with continued exertion but resolves completely with rest, although not immediately upon stopping exercise. Complete resolution of symptoms occurs shortly (typically 10 to 20 minutes) after activity is stopped and is so characteristic that the diagnosis should be reconsidered if such a correlation cannot be established. In addition, the same symptoms typically recur despite extended periods of rest once the athlete begins to run or exercise again, but the patient remains pain-free between bouts of exercise.

Neurologic symptoms such as paresthesias, numbness, and even foot-drop may occur in patients with CECS. According to one large case series, 36 percent of patients with CECS associated with pain at the anterior and/or lateral leg develop numbness in the distribution of the superficial peroneal nerve (dorsum of the foot) after the onset of pain [20]. The structures found in the muscle compartments of the upper and lower extremities, and the most common symptoms and signs associated with elevated pressures within these compartments, are described separately. (See "Acute compartment syndrome of the extremities", section on 'Anatomic compartments and related clinical signs'.)

In a study of 80 patients referred to a clinic for suspected CECS, researchers reported that compartment syndrome of the lower leg is more likely if [23]:

●Pain is induced only by athletic activity.

●Pain is limited to the anterior leg compartment.

●Pain forces the athlete to stop running.

●Tenderness is present nowhere else in the leg but the involved compartment.

The physical examination of patients suffering from CECS is often unremarkable at rest [5,17,44]. It can be helpful to examine the patient after they exercise to the point of eliciting symptoms. Immediately following such activity, the involved compartment may be tense or tender. Relative weakness of muscles in the involved compartment may be noted when compared with a pre-exercise evaluation. Such findings are not seen once compartment pressures return to normal.

Muscle hernias and palpable fascial defects may be present in patients with CECS, although, these are frequently seen in patients with other causes of lower leg pain [22,23,41]. According to observational studies, muscle hernias occur in 20 to 60 percent of patients, although the true incidence is unknown [5,14,21-23,45]. Most often the hernias themselves are asymptomatic and so may not prompt the patient to seek evaluation. However, while not themselves diagnostic, bilateral muscle hernias, particularly those that become more prominent during exercise, may be a helpful clue to the diagnosis. Fascial defects have been found in 15 to 50 percent of patients undergoing surgery for CECS [46].

Bulky, well-developed calf or anterior tibialis muscles may be noted in patients with CECS [5,21]. Abnormal distal pulses are uncommon and should lead the clinician to reconsider the diagnosis [17,21,44]. (See "Examination of the arterial pulse", section on 'Unequal or delayed pulses'.)

Although CECS may occur in any location with a muscle compartment, 95 percent of cases involve the lower extremities [1,14]. CECS involving the forearm has been described, primarily in motorcycle and motocross racers and in weightlifters but is much less common. Achiness, tightness, cramping, and weakness of the wrist flexors or extensors are among the reported findings. In one large review of upper extremity CECS, approximately 28 percent of patients had bilateral symptoms. Of note, the authors of the review state that different thresholds for elevated pressure in forearm compartments may be needed for accurate diagnosis. They found that a large proportion of patients (23 percent) whose pressures would not be considered elevated using standard criteria nevertheless improved significantly with surgical release [47]. The Pedowitz criteria used to diagnose lower extremity CECS can be applied to the upper extremities, but the paucity of relevant clinical research and lack of consensus among clinicians about measurements for upper extremity CECS makes clinical judgment even more important when diagnosing this uncommon condition. (See 'Compartment pressure measurement' below.)

There are no validated instruments that formally define CECS symptoms as mild, moderate, or severe [48]. This determination is made clinically. Symptoms are generally considered mild if gait is unaffected, the patient is able to complete their workout despite symptoms, and there are no significant neurologic findings (eg, foot drop). Conversely, symptoms that impair gait or regular daily activities, or are associated with significant neurologic findings, are considered severe.

Of note, while not common, acute-on-chronic compartment syndrome can develop, in which case pain does not resolve with rest. ACS is a limb-threatening emergency and immediate evaluation is required. (See "Acute compartment syndrome of the extremities", section on 'Clinical features'.)

DIAGNOSTIC IMAGING AND OTHER NONINVASIVE DIAGNOSTIC TECHNIQUES — Researchers continue to investigate a number of non-invasive methods for diagnosing CECS in order to avoid the need for direct, invasive intramuscular pressure measurements. Prospective techniques include: ³¹P-NMR spectroscopy [49,50], MIBI perfusion [51], magnetic resonance imaging [52,53], near-infrared spectroscopy [54], and thallium-201 single photon emission tomography [55,56]. Some clinicians use ultrasound to measure muscle compartment diameters before and after an exercise challenge to aid diagnosis [57]. Nevertheless, no noninvasive measurement technique has been accepted as an equivalent alternative to direct pressure measurement. Therefore, imaging should be considered only as a means of ruling out other potential etiologies. Bone scan and MRI may be used to look for stress fracture, stress reaction, or periostitis. Ultrasound or MRI may be used to assess for nerve or arterial entrapment.

COMPARTMENT PRESSURE MEASUREMENT

Approach to testing — If the history and physical examination suggest the diagnosis of CECS, a definitive diagnosis is made by measuring compartment pressures [18,22,43,47,58-64]. Although, some researchers believe the history and physical examination alone may be sufficient to make the diagnosis in some instances [39,65,66], most clinicians, including the authors, believe compartment pressure measurements are necessary [5,6,41,67]. In most cases where we believe CECS to be the most likely diagnosis, we may try conservative measures to alleviate symptoms and complete our work-up of other possible causes, before measuring intramuscular compartment pressures (ICP). (See 'Approach and nonsurgical treatment' below.)

For patients with occasional complaints (eg, present only during annual military fitness testing), or mild symptoms (gait is unaffected and desired workouts can be completed), who are able to perform their daily activities and work, ICP testing can be deferred and a presumptive diagnosis of CECS made. Non-surgical treatment and exercise modifications can be used in the meantime to alleviate symptoms. For patients whose symptoms are severe (eg, foot drop, unable to perform regular daily activities), progressive, and/or disruptive to their occupation or fitness regimen, ICP testing is generally performed. (See 'Approach and nonsurgical treatment' below.)

Performance and interpretation of testing — There is little high-quality evidence and no agreed upon standard for diagnosing CECS on the basis of compartment pressures [60,61,68]. Measurement techniques, the timing of the measurements in relation to exercise, and the criteria used to diagnosis CECS vary among clinicians. Furthermore, measurements may differ among clinics depending upon the type of catheter used and whether the patient can reproduce the pain caused by exercising at the time measurements are taken. Therefore, to improve accuracy, compartment pressures should be measured by clinicians with experience performing the procedure using standardized equipment and techniques (figure 3).

Of note, some authors caution against blind, transcutaneous measurements of the deep posterior compartment of the lower leg given the potential for neurovascular injury [42]. Some clinicians use ultrasound to help with needle placement when measuring the deep posterior compartment [69,70].

The most widely used diagnostic criteria for CECS, which we use in our clinics, are those proposed by Pedowitz et al [5,22,71-73]. (Note that these criteria were developed for CECS of the leg. No widely agreed upon criteria to diagnose CECS of the upper extremity have been developed.) According to these criteria, CECS of the leg is present if one or more of the following intramuscular compartment pressure (ICP) criteria are met:

●Pre-exercise pressure ≥15 mmHg

●One-minute post-exercise pressure of ≥30 mmHg

●Five-minute post-exercise pressure ≥20 mmHg

A systematic review of studies that assessed methods for measuring compartment pressure in CECS noted that in the six studies that included a 1 minute postexercise compartment pressure measurement, there was no overlap in the mean pressures obtained in patients (34 to 55.4 mmHg) and controls (9 to 19 mmHg) at that time, suggesting that 1 minute is a useful interval when obtaining pressures to diagnose CECS [60]. According to the Pedowitz criteria, only one or more of the elevated ICP measurements is needed for diagnosis, and therefore some clinicians believe that confirmatory findings in the presence of characteristic symptoms at 1 minute obviate the need for further testing at 5 minutes.  

Rates of elevated pressures vary among leg compartments, and more than one compartment may be affected. In a retrospective review involving 226 patients and 153 confirmed cases of CECS, the anterior compartment was elevated in 42 percent, the lateral compartment in 35.5 percent, the deep posterior in 19 percent, and the superficial posterior in 3 percent [20]. Pedowitz criteria were used to make the diagnosis. In 39.6 percent of cases, two compartments were affected (typically the anterior and lateral), but 37 percent of cases involved a single compartment. Three compartments were affected in 17.6 percent of patients, while only 4.8 percent involved all four compartments.

Although most practitioners measure ICP in both lower extremities at rest and after exercise, some experienced clinicians advocate a more limited approach to ICP testing. They measure ICP only in symptomatic compartments after an exercise challenge (they do not perform testing at rest), and measure ICP only in the more symptomatic leg of patients with bilateral symptoms [74]. Most often, this approach is taken with patients whose history and clinical findings are suggestive of CECS, and whose symptoms are severe enough to warrant surgical intervention if ICP values confirm the diagnosis. If surgical intervention is not among the treatment options, ICP testing may be deferred and presumptive treatments explored. (See 'Approach and nonsurgical treatment' below.)

Investigational approaches — The measurement of intramuscular pressures during exercise (dynamic measurement) has been limited by technical difficulties, but studies of this approach continue. In a small, preliminary study, researchers reported that direct measurements obtained during maximal patient discomfort while they were exercising on a treadmill accurately predicted CECS [75]. Further investigation of these techniques is needed.

Direct intramuscular pressure measurement is an invasive procedure. Alternative, noninvasive means of accurately measuring muscle compartment pressures are the subject of ongoing research. These are discussed separately. (See "Acute compartment syndrome of the extremities", section on 'Investigational techniques'.)

DIAGNOSIS — The diagnosis of CECS is made by measuring compartment pressures and finding them to be elevated in a patient whose history and physical examination suggest the diagnosis. A presumptive diagnosis may be made on the basis of the clinical presentation alone. The typical presentation for CECS is a young athlete, often a runner, who describes gradually increasing pain in a specific muscle region (usually the lower leg) during physical exertion. Pain generally begins within several minutes of starting the inciting activity and resolves completely with rest, although not immediately upon stopping exercise.

DIFFERENTIAL DIAGNOSIS — The differential diagnosis for CECS primarily includes other causes of leg pain. Common alternative diagnoses to rule out in athletes include medial tibial stress syndrome, stress fracture, and tendinopathy, and deep vein thrombosis is an important consideration. The history and physical examination often distinguish alternative diagnoses from CECS.

●Medial tibial stress syndrome (MTSS, also referred to as “shin splints” or tibial periostitis) ‒ The pain associated with CECS is brought on by and occurs during exertion, and resolves quickly with rest, typically within 10 to 20 minutes. In contrast, the pain associated with MTSS does not develop until a day or a few days after the inciting activity, but once present typically persists to some degree even at rest, and is exacerbated by activities of daily living or exercise. Complete resolution of symptoms from MTSS typically requires days or weeks of rest from exercise. On examination, MTSS typically produces tenderness along the posteromedial tibial periosteum of patients, but leg compartments are not tense; CECS does not cause bony tenderness. (See "Running injuries of the lower extremities: Patient evaluation and common conditions", section on 'Medial tibial stress syndrome (shin splints) and tibial stress fractures'.)

●Stress fracture of the tibia or fibula ‒ If an athlete continues to exercise, the pain from stress fractures increases gradually over days to weeks, is often exacerbated by daily activities, and causes focal tenderness over the involved portion of the tibia or fibula. Pain begins with weight bearing and worsens with activity. In contrast, pain due to CECS does not develop until the patient has engaged in the inciting activity (typically running) for several minutes. Although plain radiographs obtained early in the development of a stress fracture may be negative, advanced imaging studies or plain radiographs repeated weeks later reveal the fracture. (See "Stress fractures of the tibia and fibula".)

●Tendinopathy ‒ In contrast to CECS, the pain from tendinopathy is chronic, typically has increased over weeks, and is brought on immediately with activity involving the affected muscle group. Tendinopathy usually causes focal tenderness of the involved tendon, and strength or mobility testing of the specific muscle group elicits focal pain. Muscle compartments are not tense. (See "Overview of the management of overuse (persistent) tendinopathy".)

●Deep vein thrombosis ‒ Deep vein thrombosis (DVT) typically presents with gradually worsening pain and swelling in the posterior calf. Pain is unrelated to any specific activity, swelling is generalized, and there is no focal tenderness. The patient may have risk factors for venous thrombosis (eg, recent trauma or surgery, history of prior DVT or cancer, coagulopathy, pregnancy). DVT is potentially life-threatening, and an appropriate workup must be performed if the diagnosis is suspected. (See "Clinical presentation and diagnosis of the nonpregnant adult with suspected deep vein thrombosis of the lower extremity".)

Of note, clinicians should carefully rule out DVT, as well as chronic injury to the gastrocnemius or soleus muscles and tendons, prior to reaching a diagnosis of superficial posterior compartment syndrome, as this occurs in only 3 percent of cases of CECS, and requires invasive testing for diagnosis.

●Popliteal artery entrapment ‒ Popliteal artery entrapment (PAE) typically presents as pain deep in the calf that develops only after an intense workout involving repeated ankle dorsiflexion and plantarflexion (eg, cycling, running, marching up and down hills). Symptoms may resemble calf claudication. During exercise, the patient may experience paresthesias across the proximal posterior calf, while immediately following exercise the foot and toes may become pale or discolored. At all other times, the patient typically has no pain, and the examination at rest is normal. Diminished distal pulses either at baseline or noted while the patient performs repeated heel raises suggests the diagnosis. Some studies suggest that a high proportion of patients with CECS have concomitant PAE [76]. Although this work is preliminary, it does suggest that these conditions coexist in a subset of patients. (See "Calf injuries not involving the Achilles tendon", section on 'Popliteal artery entrapment'.)

Other conditions to consider in the differential diagnosis include the following:

●Lumbar radiculopathy (see "Acute lumbosacral radiculopathy: Etiology, clinical features, and diagnosis", section on 'Clinical presentations')

●Peripheral nerve entrapment or contusion (peroneal, saphenous, sural) (see "Overview of lower extremity peripheral nerve syndromes") [77,78]

●Neurogenic claudication

●Vascular claudication (see "Clinical features and diagnosis of lower extremity peripheral artery disease", section on 'Clinical presentations')

●Cystic adventitial disease of the popliteal artery [79]

●Myopathy

●Bone tumor

With the diagnoses listed above, the history and physical examination alone are usually sufficient to distinguish them from CECS. As examples, radiculopathies generally cause pain at rest that radiates from the lower back to the thigh and leg. In severe cases, localized weakness and diminished reflexes may be present. In nerve entrapment syndromes, paresthesias, numbness, and burning sensations that radiate are more prominent and examination may reveal weakness or atrophy of the muscles innervated by the involved nerve. Pain induced by tapping the site of entrapment (positive Tinel sign) may be noted [41].

MANAGEMENT

Approach and nonsurgical treatment — Many conditions can mimic CECS, and definitive diagnosis requires invasive measurement of compartment pressures. For these reasons, we investigate other potential causes of exertional leg pain, while implementing conservative management, prior to measuring pressures. (See 'Differential diagnosis' above.)

In most cases of CECS, symptoms resolve when the patients stops engaging in the activities that cause them. However, this solution is unacceptable to many athletes, and symptoms from moderate to severe CECS persist during exercise if left untreated [80]. For some percentage of patients with mild CECS, the conservative measures described below provide sufficient relief with little if any risk [81].

Although high quality evidence to guide interventions is lacking, common conservative interventions may include:

●Running on softer surfaces, such as grass, woodland trails, dirt, or forgiving modern synthetic tracks.

Hard surfaces that increase impact forces (eg, concrete), or surfaces that place significantly greater eccentric loads on the tibialis anterior muscle (eg, sand), may provoke symptoms in some athletes. In addition, up-hill running (which requires increased ankle dorsiflexion at foot strike) or increased running speed with a fixed cadence may worsen symptoms [82].

●Using orthotics, other shoe inserts, or athletic shoes that provide a better fit or greater comfort.

●Reducing training volume – Patients may cross train (combine cycling or swimming with reduced running) to maintain fitness, then gradually increase their running once symptoms resolve

●Addressing deficiencies in strength or flexibility of the lower extremities and torso. A physical therapy referral may be useful.

●Icing the affected area after training

Gait retraining has shown promise for reducing symptoms during distance running in small observational studies [82,83]. Some researchers approach CECS in runners as an overload syndrome and by making biomechanical adjustments in gait are able to reduce loads and improve symptoms. However, this approach has not reduced compartment pressures or consistently improved long-term tolerance to sports that require frequent change of direction and pace, such as soccer or field hockey [84,85].

Other less traditional, non-operative interventions have been used, but none has demonstrated results that are consistently superior to surgical fasciotomy. Interventions have included massage of the lower extremity compartments [81,86,87] and needle fenestration [88]. Chemodenervation with botulinum toxin A (boNT-A) has been proposed for treatment of CECS in the anterior and lateral leg compartments [89], but further research is needed to establish the efficacy and safety of this treatment.

If the workup for other potential causes of exertional pain is unrevealing and conservative management fails to alleviate symptoms, we proceed with compartment pressure measurements. We refer patients with elevated compartment pressure measurements who intend to continue with sport or exercise to an orthopedic surgeon for possible muscle compartment release. We also refer patients who have progressively worsening symptoms from minimal activity. To date, no alternative nonoperative approach has been successful for treating refractory symptoms [1,5,42,45,72]. (See 'Compartment pressure measurement' above.)

Surgical treatment

Indications, overall results, and other important points — Once CECS is diagnosed by compartment pressure measurement, patients whose symptoms fail to improve with non-surgical interventions and who wish to continue with sport or exercise should be referred to an orthopedic surgeon for possible muscle compartment release. Surgical release of the involved compartments is considered standard treatment of moderate to severe cases of CECS, and cases that do not improve with conservative care in patients who wish to continue engaging in activities that elicit symptoms. Ideally, the surgeon should have experience managing CECS. (See "Lower extremity fasciotomy techniques", section on 'Alternative fasciotomy techniques for CECS'.)

While controlled trials are lacking, according to available studies, surgical management of CECS using either fasciotomy or fasciectomy appears to yield good results in many cases [27,72,90-94]. Success is defined as resolution of symptoms and successful return to full activity. Short- and medium-term follow-up data from multiple observational studies suggest that approximately 70 to 80 percent of patients return to full activity following surgical release [27,90-94], which is consistent with our experience.

However, as described in greater detail below, the reported outcomes of surgical interventions vary widely depending on several factors, including age, gender, military status, and the compartments involved [27,73,91-93,95-97]. Even in the most optimistic reports, surgical success rates do not exceed 90 percent. Success rates are consistently lower among military personnel and cases involving the deep posterior compartment. These inconsistent results suggest the need for improvements in non-operative and surgical treatment, and perhaps for more accurate pre-operative testing. (See 'Variability in study results: Lower success rates in military and females' below and 'Surgical success by location' below.)

Additional important points about surgical management of CECS include the following:

●For reasons that remain unclear, surgical success rates appear to be lower among military personnel and females. (See 'Variability in study results: Lower success rates in military and females' below.)

●Repeat surgery for incomplete resolution or recurrence of symptoms is relatively common. Symptoms recur in up to approximately 20 percent of patients following their initial procedure, although reported recurrence rates are higher among military personnel [18,24,42,44].

●Cure rates are higher for surgical treatment of CECS involving the anterior and lateral leg compartments compared with the deep posterior compartment. Given the relatively high failure and complication rates associated with surgical management involving the deep posterior compartment, clinicians must consider other causes of pain besides CECS before fasciotomy is performed. (See 'Surgical success by location' below and 'Differential diagnosis' above.)

●Controlled studies are lacking so there is no strong evidence supporting a preference for any particular surgical technique. Several studies report no correlation between ICP measurements and successful outcomes following surgery [90,98]. (See 'Surgical technique' below.)

Variability in study results: Lower success rates in military and females — The following studies provide examples of the variability in surgical results. In a retrospective study of 155 pediatric patients (mean age 16.4), 79.5 percent returned to sport after surgical release [24]. Of note, in this cohort 18.8 percent required a second operation. In contrast, a retrospective study of 611 active United States military personnel diagnosed with CECS reported that a substantial percentage experienced recurrence (44.7 percent) or failed to return to full duty (27.7 percent) following surgical treatment [99]. Although this study did not provide a clear description of how CECS was defined or diagnosed and is limited by its retrospective design, its results are consistent with several other observational studies that reported a lower percentage of military recruits able to return to full activity following fasciotomy compared to civilian populations [100,101]. The reasons for this difference remain unclear, but the finding suggests that a cautious approach to surgical intervention is prudent when caring for military personnel [14].

Surgical success rates may be lower in female athletes, again, for reasons that remain unclear. One review of females treated surgically for CECS reported a success rate of 76 percent and the authors noted that other published studies confirm higher failure rates among women [72]. The case series described above with 155 patients, primarily involved adolescent female athletes (n = 136), and 79.5 percent were able to return to sport, while 18.8 percent developed recurring symptoms requiring reoperation [24]. Of note, patients in this study treated with four-compartment fasciotomies had a lower likelihood of recurrence than those treated with fasciotomy of only the anterior and lateral compartments.

Surgical success by location — Over 80 percent of cases of CECS in the leg involve the anterior or lateral leg compartments, whereas approximately 13 percent involve the deep posterior compartment. Surgical cure rates are higher in CECS involving the anterior and lateral compartments compared with the deep posterior compartment [71,95,97,102-104]. Open fasciotomy of the anterior compartment is successful in over 80 percent of cases, according to observational studies, while the success rate for the deep posterior compartment is consistently lower (30 to 65 percent in most studies), leading some researchers to conclude that the inclusion of the deep posterior compartment may negatively bias the results of large studies [105]. A systematic review of seven studies of surgical treatments for CECS involving the deep posterior compartment, including superficial crural fasciotomy and multiple fasciotomies, emphasized the absence of controlled trials, variability in diagnostic criteria, relatively poor success rates, and the absence of known risk factors for surgical failure [104]. No particular surgical procedure was found to be superior.

Substantially higher surgical success rates and fewer complications have been reported for the surgical management of forearm cases of CECS, which are seen most often in competitive motorcycle racers. Although large clinical series are lacking, in a study of 34 racers (56 compartments released), 94 percent of patients reported satisfaction with the results at a mean follow up of 45 months [106].

Surgical technique — Well-performed, controlled trials supporting the use of a particular surgical technique are lacking. Some authors prefer partial open fasciectomy to simple fasciotomy [18,42]. In an observational study of CECS, 109 patients underwent open fasciectomy with extended subcutaneous fasciotomy while 100 patients underwent subcutaneous fasciotomy [42]. Symptoms recurred less often in the open fasciectomy group (2 percent) than the fasciotomy group (11 percent). In addition, lower rates of intraoperative and early postoperative complications were reported in the open fasciectomy group. Other authors have not found a significant long-term benefit from partial fasciectomy and fasciotomy over simple fasciotomy [73].

Surgical success rates for CECS are reported to be similar for endoscopic-assisted versus minimally invasive release of lower extremity compartments [92]. However, this is based on limited observational data. Similarly, no difference in success rates for open versus minimally invasive fasciotomies has been reported for cases of forearm CECS.

Complications — Limited information is available to compare complication rates by surgical technique. There is no generally accepted technique for endoscopic or minimally invasive procedures, surgical techniques are often poorly described in studies, and authors discussing their case series typically describe using modifications of standard techniques. As one example, the distinction between open and minimally invasive procedures is often subjective (eg, in one study the incision length threshold was arbitrarily set at 2.5 cm) [92]. In addition, studies describing endoscopic-assisted release involve small numbers.

With the above limitations in mind, one can make rough estimates of complications such as wound infection and hematoma, which are noted in most studies and reviews. Open fasciotomy appears to have fewer postoperative wound complications (6 versus 11 percent) compared to subcutaneous fasciotomy, and fewer late recurrences (2 versus 11 percent) [92,100]. Superficial peroneal nerve injury and chronic ankle pain may be caused by minimally invasive fasciotomies of the anterior compartment that are performed too distally [107]. Reported complication rates following fasciotomy, including nerve injury and surgical site infection, range from 11 to 13 percent [24,27]. (See 'Prognosis' below.)

Return to play following surgery — Decisions about when athletes can return to sports are generally made by the surgeon, but case series report that most athletes return between 8 to 12 weeks postoperatively [71,95].

PROGNOSIS — Evidence pertaining to the long-term outcome for patients with CECS is limited. A few observational studies of nonsurgical treatment report encouraging outcomes [81,83-85], but the general consensus is that conservative measures are only effective in mild cases. Without cessation of symptom-inducing activities, the prognosis for patients treated nonoperatively for moderate to severe CECS is poor [1,5,42,45,72].

Without surgical treatment, reoccurrence of symptoms is typical, even after weeks or months of avoiding exercise. Occasionally, symptoms may gradually worsen and begin to affect activities of daily living such as walking, at which point patients may feel compelled to pursue surgery regardless of their athletic status. Rarely, patients who continue to engage in prolonged periods of exertion without rest, despite escalating symptoms, develop significant tissue ischemia and irreversible swelling in the compartments, requiring emergency fasciotomies similar to traumatic compartment syndrome.

Although controlled studies are lacking, reported surgical success rates vary by compartment and other factors (eg, active military duty, gender, age). Systematic reviews of the limited evidence available suggest that surgical treatment of lower extremity CECS is successful in approximately two-thirds of young athletic patients, while approximately 70 to 80 percent of general patients are satisfied with their outcomes at short to mid-term follow up [27,91,108-110]. Success rates for military personnel are consistently lower. Further detail pertaining to surgery and surgical outcomes is reviewed above. (See 'Surgical treatment' above.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Extremity compartment syndrome".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Chronic compartment syndrome (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Pathophysiology and epidemiology – Chronic exertional compartment syndrome (CECS) is a reversible form of acute compartment syndrome that develops when increased hydrostatic pressure within a skeletal muscle compartment compromises local tissue perfusion leading to pain and other symptoms. CECS typically affects young endurance athletes, particularly distance runners. Military recruits and personnel appear to be at increased risk. Sudden increases in training volume may increase risk. (See 'Epidemiology and risk factors' above and 'Definition and pathophysiology' above.)

●Clinical presentation – The typical patient with CECS is a young athlete, often a runner, who describes gradually increasing pain in a specific muscle region (usually the lower leg) during physical exertion. Pain develops shortly after the start of exercise and resolves soon (typically within 10 to 20 minutes) after the activity stops. The reproducibility of symptoms is a distinctive characteristic of CECS. Runners often can describe the time or distance required for symptoms to develop. The pain may be described as aching, squeezing, cramping, or tightness. Patients are typically asymptomatic at rest and during activities of daily living. (See 'Clinical features' above.)

●Physical examination – Physical examination is often unremarkable at rest, and the condition is often misdiagnosed initially. Examining the patient after they exercise to the point of provoking symptoms may allow the clinician to detect tenderness or tenseness in the involved compartment. Relative weakness of muscles in the involved compartment may be noted when compared with a pre-exercise evaluation. (See 'Clinical features' above.)

●Diagnosis – While the history and examination may be strongly suggestive, definitive diagnosis is made by direct measurement of compartment pressures. Diagnostic threshold pressures vary among experts; our approach is described in the text. Compartment pressures should be measured by clinicians with experience performing the procedure using standardized equipment and techniques. Proposed noninvasive diagnostic techniques lack specificity. (See 'Compartment pressure measurement' above and 'Diagnostic imaging and other noninvasive diagnostic techniques' above.)

●Differential diagnosis – Many conditions can mimic CECS, including medial tibial stress syndrome (shin splints), stress fracture of the tibia or fibula, tendinopathy, and deep vein thrombosis. Alternative diagnoses can usually be distinguished from CECS on the basis of a careful history and physical examination. (See 'Differential diagnosis' above.)

●Management – Initial management consists of conservative measures, such as reducing training volume, addressing strength or flexibility deficiencies, and using orthotics. Patients whose symptoms persist despite conservative measures, who are unwilling to stop the inciting activity, and who have elevated compartment pressures are referred for surgical evaluation. (See 'Approach and nonsurgical treatment' above.)

Surgical treatment consists of either fasciotomy or fasciectomy and appears to be successful in most cases, although controlled trials are lacking. Success rates vary, in part depending upon the involved compartment. Most cases involve the anterior or lateral compartment, and these have the highest success rates. Military personnel and female patients appear to have lower surgical cure rates. (See 'Surgical treatment' above.)