Compartment Syndrome: Symptoms, Causes & Emergency Treatment

What Is Compartment Syndrome?

Compartment syndrome is a serious condition where increased pressure within a closed muscle compartment compromises blood flow and tissue perfusion. Without treatment, this can lead to permanent muscle and nerve damage within hours. The condition most commonly affects the legs and arms but can occur in other body parts.

Your muscles are organized into groups surrounded by tough, inelastic fascial membranes that create enclosed spaces called compartments. These compartments contain muscles, nerves, and blood vessels. The fascial walls do not stretch, so when pressure increases inside a compartment - whether from swelling, bleeding, or external compression - there is nowhere for the pressure to go.

As pressure rises within the compartment, it begins to exceed the pressure in the small blood vessels (capillaries) that supply oxygen and nutrients to the muscles and nerves. When this happens, blood flow to the tissues decreases significantly. Without adequate blood supply, the tissues begin to suffer from ischemia - a lack of oxygen that causes cellular damage and eventual tissue death.

The pathophysiology follows a vicious cycle: initial injury causes swelling, which increases pressure, which reduces blood flow, which causes more tissue damage and more swelling. This cycle can progress rapidly, making time a critical factor in treatment. Research shows that muscle can tolerate ischemia for approximately 4-6 hours before irreversible damage begins. After 6-8 hours, the damage may become permanent.

Compartment syndrome represents a unique medical challenge because the problem is mechanical - increased pressure - rather than purely vascular or infectious. This is why the treatment is also mechanical: surgically opening the compartment to release the pressure. No medication can substitute for surgical decompression in acute compartment syndrome.

Anatomy of Muscle Compartments

Understanding the anatomy helps explain why compartment syndrome occurs. The lower leg, for example, contains four distinct compartments: the anterior compartment (front of the shin), lateral compartment (outer side), superficial posterior compartment (calf), and deep posterior compartment. Each contains specific muscles and is supplied by particular nerves and blood vessels.

The anterior compartment of the lower leg is the most commonly affected location, accounting for approximately 36% of all acute compartment syndrome cases. This compartment contains the tibialis anterior muscle (which lifts the foot) and the deep peroneal nerve. When this compartment is affected, patients often notice numbness in the web space between the first and second toes - the specific area supplied by this nerve.

The forearm also has multiple compartments and is the second most common site for acute compartment syndrome, particularly following distal radius fractures (broken wrists). The thigh, hand, foot, and even the abdomen and buttocks can develop compartment syndrome under certain circumstances.

What Causes Compartment Syndrome?

Compartment syndrome has two main types: acute compartment syndrome, caused by trauma like fractures, crush injuries, or tight casts; and chronic exertional compartment syndrome, caused by repetitive exercise that temporarily increases compartment pressures. The causes determine whether it's a medical emergency.

Acute Compartment Syndrome Causes

Acute compartment syndrome develops suddenly and requires emergency treatment. The most common cause is tibial fracture (broken shin bone), which accounts for approximately 36% of all cases. The fracture causes bleeding and swelling within the compartments, rapidly increasing pressure. Other fractures, particularly of the forearm, can also lead to compartment syndrome.

Crush injuries are another major cause. When a limb is compressed for an extended period - such as in industrial accidents, building collapses, or prolonged unconsciousness in one position - the muscles suffer direct damage. Once the compression is released, the damaged muscles swell dramatically, potentially triggering compartment syndrome. This is sometimes called reperfusion injury because the damage worsens when blood flow returns to the area.

External compression from tight casts, bandages, or splints can cause compartment syndrome even without significant underlying injury. This is why healthcare providers carefully monitor patients with new casts for signs of developing compartment syndrome. The swelling that naturally occurs after an injury may have nowhere to go if constrained by a rigid cast, leading to dangerous pressure buildup.

Other causes of acute compartment syndrome include:

• Burns - both thermal burns and electrical injuries can cause significant tissue swelling
• Snake bites - venom can cause massive local swelling and tissue damage
• Bleeding disorders or anticoagulant medication leading to compartment hemorrhage
• Intravenous infiltration - when IV fluids leak into surrounding tissue
• Post-surgical complications - particularly after vascular surgery or procedures with prolonged limb positioning
• Drug overdose - prolonged immobility in one position causing crush-like injury

Chronic Exertional Compartment Syndrome

Chronic exertional compartment syndrome (CECS) is fundamentally different from the acute form. It develops gradually over weeks to months and is associated with repetitive exercise, particularly running. During intense physical activity, blood flow to muscles increases by 10-20 times, and muscles can swell by 20% of their resting volume. In some individuals, this normal response leads to compartment pressures high enough to cause symptoms.

CECS most commonly affects young, athletic individuals - particularly runners, soccer players, and military personnel. The anterior compartment of the lower leg is the most frequently affected area. Symptoms typically begin after a predictable amount of exercise time and resolve with rest, which distinguishes CECS from acute compartment syndrome.

The exact cause of CECS is not fully understood. Some theories suggest that affected individuals may have less compliant fascia (the tissue is stiffer and doesn't stretch as well), smaller compartments relative to muscle mass, or abnormal responses to exercise. Importantly, CECS is not a surgical emergency and can often be managed with activity modification or elective surgery.

What Are the Warning Signs of Compartment Syndrome?

The classic warning signs of compartment syndrome are known as the "6 Ps": Pain (out of proportion, worse with passive stretch), Pressure (tense swelling), Paresthesia (numbness/tingling), Paralysis (inability to move), Pallor (pale skin), and Pulselessness (late sign). Severe pain that increases when muscles are passively stretched is the most reliable early sign.

Recognizing compartment syndrome early is critical because the window for effective treatment is narrow. Healthcare providers are trained to maintain a high index of suspicion in at-risk patients, but understanding the warning signs can help patients and families advocate for appropriate evaluation.

Pain - The Most Important Sign

Pain is the earliest and most reliable symptom of developing compartment syndrome. Critically, the pain is out of proportion to the visible injury. A patient with a simple fracture who is experiencing excruciating pain despite appropriate pain medication should be evaluated for compartment syndrome. The character of the pain is often described as deep, burning, or aching.

The most specific sign is pain with passive stretch of the muscles in the affected compartment. For example, if the anterior compartment of the lower leg is affected, passively flexing the toes downward will stretch the muscles in that compartment and cause severe pain. This occurs because stretching the already-compressed muscles further reduces blood flow and increases ischemia. Pain with passive stretch may be present even before other signs develop.

Patients often describe the pain as unrelenting and not relieved by pain medications that would normally be effective. The pain may worsen rapidly over hours, reflecting the progressive nature of the compartment pressure buildup.

Pressure and Swelling

The affected limb segment typically feels tense and swollen. Unlike normal post-injury swelling which feels soft and compressible, a compartment with elevated pressure feels firm and tight - often described as "woody" or "drum-like." The skin may appear shiny due to the underlying tension.

Palpating (feeling) the compartment may cause significant pain for the patient. Healthcare providers assess this by comparing the affected compartment to the same compartment on the other limb and to adjacent compartments on the same limb.

Paresthesia and Neurological Changes

Paresthesias - abnormal sensations like numbness, tingling, or "pins and needles" - indicate that the nerves within the compartment are being affected by the increased pressure. The specific distribution of these sensory changes can help identify which compartment is involved.

For anterior compartment syndrome in the lower leg, patients often first notice numbness or altered sensation in the first web space - the area between the big toe and second toe. This is because the deep peroneal nerve, which supplies sensation to this area, runs through the anterior compartment. Testing sensation in this specific area is an important part of monitoring at-risk patients.

Paralysis and Weakness

Paralysis or significant weakness of the muscles in the affected compartment is a concerning sign that indicates more advanced compartment syndrome. In the anterior compartment of the leg, this would manifest as weakness or inability to dorsiflex the foot (pull the foot up toward the shin) or extend the toes.

Motor weakness develops later than sensory changes because motor nerve fibers are somewhat more resistant to ischemia than sensory fibers. However, once motor function is affected, the window for successful treatment may be closing.

Pallor and Pulselessness - Late Signs

Pallor (pale skin color) and pulselessness (absent peripheral pulses) are late signs that indicate severe compartment syndrome. It's crucial to understand that waiting for these signs is dangerous - by the time pulses are affected, significant irreversible damage may already have occurred.

The major arteries that supply the limb run through the compartments and are relatively large vessels. Compartment pressure typically rises enough to compromise the small capillaries (affecting tissue perfusion) well before it becomes high enough to compress the major arteries and abolish pulses. Therefore, the presence of normal pulses does NOT rule out compartment syndrome.

When Should You Seek Emergency Care?

Seek emergency care immediately if you experience severe pain after an injury that seems worse than expected, especially if pain increases when someone moves your fingers or toes. Also seek immediate care if you develop increasing pain, numbness, or difficulty moving after having a cast or tight bandage applied. Acute compartment syndrome is a surgical emergency.

Time is the critical factor in compartment syndrome outcomes. Studies consistently show that fasciotomy performed within 6 hours of symptom onset results in significantly better outcomes than delayed surgery. After 6-8 hours, the risk of permanent complications rises sharply. After 12 hours, the likelihood of normal recovery decreases dramatically.

Seek Emergency Care If:

• You have severe pain after a fracture or injury that doesn't improve with pain medication
• Pain increases when someone gently moves your fingers or toes (passive stretch test)
• The injured area feels extremely tight, tense, or hard
• You notice numbness, tingling, or loss of sensation in the injured limb
• You cannot move your fingers or toes as well as normal
• After getting a cast or splint, pain increases rather than decreases
• The skin color changes to pale or blue in the injured area

If you are unable to reach emergency services immediately, there are some important first aid measures. If a cast or bandage appears too tight and you notice warning signs, the cast should be loosened or split immediately - this can be done even by non-medical personnel in an emergency. Remove all constrictive jewelry, clothing, or bandages. Keep the limb at heart level (not elevated above the heart, as this can reduce blood flow further).

Special Considerations for Patients in Casts

Compartment syndrome can develop even days after a cast is applied, as continued swelling from the original injury can increase compartment pressures. Warning signs specific to cast-related compartment syndrome include:

• Pain that increases rather than decreases over time
• Pain that is not controlled by prescribed pain medications
• Numbness or tingling in the fingers or toes of the casted limb
• Difficulty moving the fingers or toes
• The cast feeling progressively tighter

If these symptoms occur, the cast needs to be split or removed urgently. Do not wait for a scheduled appointment - seek immediate care. Healthcare providers are trained to cut the cast along its entire length (bivalving) to relieve any external compression.

How Is Compartment Syndrome Diagnosed?

Compartment syndrome is primarily diagnosed clinically based on symptoms and physical examination. In uncertain cases, intracompartmental pressure measurement using a needle and pressure monitor can confirm the diagnosis. A pressure of 30 mmHg or higher, or a pressure within 30 mmHg of the patient's diastolic blood pressure (delta pressure), indicates compartment syndrome requiring surgery.

The diagnosis of compartment syndrome often relies heavily on clinical assessment because time is critical. Experienced clinicians may proceed directly to surgical treatment based on clear clinical findings without waiting for pressure measurements. However, pressure monitoring can be valuable when the diagnosis is uncertain, when the patient cannot communicate symptoms (unconscious, sedated, or very young patients), or to support clinical judgment.

Clinical Examination

The physical examination for suspected compartment syndrome includes systematic assessment of the "6 Ps" as well as comparison with the uninjured limb. The examiner will:

• Assess pain level and whether it's proportionate to the injury
• Perform passive stretch testing - gently moving the fingers or toes to stretch the muscles and observing for pain
• Palpate the compartments to assess tenseness and tenderness
• Test sensation, particularly in the web spaces of the hand (for forearm compartment syndrome) or foot (for leg compartment syndrome)
• Assess motor function - ability to move fingers, toes, wrist, or ankle
• Check peripheral pulses and capillary refill

Intracompartmental Pressure Measurement

When clinical findings are equivocal or when objective confirmation is needed, intracompartmental pressure measurement provides direct assessment of the pressure within the muscle compartment. This involves inserting a needle attached to a pressure monitoring device into the compartment.

Two criteria are commonly used to interpret pressure measurements:

• Absolute pressure ≥30 mmHg - compartment pressure of 30 mmHg or greater suggests compartment syndrome
• Delta pressure ≤30 mmHg - when the difference between the diastolic blood pressure and compartment pressure (delta P) is 30 mmHg or less, this indicates inadequate perfusion pressure

The delta pressure concept recognizes that tissue perfusion depends on both compartment pressure and the patient's blood pressure. A patient with low blood pressure may develop compartment syndrome at lower absolute compartment pressures.

Pressure measurement should be performed close to the fracture site if there is one, as pressures are typically highest near the zone of injury. Multiple compartments may need to be measured, particularly in the lower leg which has four separate compartments.

Additional Studies

Laboratory tests may be ordered to assess for complications. Creatine kinase (CK) levels rise when muscle tissue is damaged and can indicate the extent of muscle injury. Significantly elevated CK levels suggest rhabdomyolysis (muscle breakdown) which can lead to kidney damage. Kidney function tests and urine myoglobin may be monitored if rhabdomyolysis is suspected.

Imaging studies such as X-rays are typically performed to evaluate for fractures but do not directly diagnose compartment syndrome. MRI can show muscle edema and damage but is rarely used acutely because it delays treatment.

How Is Compartment Syndrome Treated?

The definitive treatment for acute compartment syndrome is emergency fasciotomy - surgical incisions through the skin and fascia to release pressure within all affected compartments. This must be performed urgently, ideally within 6 hours. For chronic exertional compartment syndrome, initial treatment involves activity modification, with elective fasciotomy available if conservative management fails.

Emergency Fasciotomy for Acute Compartment Syndrome

Fasciotomy is a surgical procedure where the surgeon makes incisions through the skin and the tough fascial membrane that surrounds the muscle compartment. This immediately releases the pressure, allowing blood flow to resume to the compressed tissues. The surgery is performed under general or regional anesthesia.

For lower leg compartment syndrome, the standard approach involves two-incision four-compartment fasciotomy. One incision on the lateral (outer) aspect of the leg allows release of the anterior and lateral compartments. A second incision on the medial (inner) aspect allows release of the superficial and deep posterior compartments. All four compartments must be released to ensure complete decompression.

For forearm compartment syndrome, both the volar (palm side) and dorsal (back of hand) compartments typically need to be released. The surgeon may extend incisions into the hand if necessary.

A critical aspect of fasciotomy is that the wounds are left open after surgery. The skin cannot be closed because the swollen muscles bulge through the incisions. Attempting to close the skin immediately would recreate the compartment syndrome. Instead, the wounds are covered with sterile dressings and the patient returns to the operating room every 24-48 hours for reassessment.

As swelling resolves over the following days to weeks, the wounds may be closed primarily (the edges brought together) or may require skin grafting if significant muscle swelling prevents closure. The wounds typically require 1-3 additional surgeries before final closure.

Immediate Measures Before Surgery

While awaiting emergency surgery, several measures can help:

• Remove all constrictive dressings - any cast should be completely bivalved (cut down both sides) and spread open, circumferential bandages should be removed
• Position the limb at heart level - not elevated above the heart, as this can reduce arterial inflow
• Provide supplemental oxygen - maximizes oxygen content of blood reaching the tissues
• Maintain blood pressure - adequate blood pressure is needed to perfuse the compartment
• Provide pain control - though pain out of proportion may be monitored as a diagnostic sign

Treatment for Cast-Related Compartment Syndrome

When compartment syndrome develops under a cast, the immediate treatment is complete release of the cast. This means not just cutting the cast but also cutting through all underlying padding and bandages down to the skin. Studies show that bivalving a cast (cutting it into two halves) can reduce compartment pressure by up to 65%.

If symptoms do not improve promptly after cast release, emergency fasciotomy may still be necessary. Patients should be monitored closely after cast manipulation.

Treatment for Chronic Exertional Compartment Syndrome

Unlike acute compartment syndrome, chronic exertional compartment syndrome (CECS) is not an emergency and can be managed with conservative measures initially:

• Activity modification - reducing training intensity, switching to lower-impact activities (swimming, cycling instead of running)
• Gait analysis and correction - some running mechanics may predispose to CECS
• Stretching and physical therapy - though evidence for effectiveness is limited
• Footwear changes - proper fitting shoes, orthotics in some cases
• Massage and manual therapy - may provide symptomatic relief

If conservative management fails and symptoms significantly impact quality of life or athletic performance, elective fasciotomy may be considered. The surgery for CECS is similar to that for acute compartment syndrome but is performed in a planned, non-emergency setting. Success rates for surgical treatment of CECS are approximately 80-90%, with most patients able to return to their previous activity levels.

What Are the Complications of Compartment Syndrome?

Untreated or delayed treatment of compartment syndrome can result in devastating permanent complications including Volkmann's ischemic contracture (permanent muscle shortening), nerve damage causing chronic weakness or numbness, rhabdomyolysis leading to kidney failure, chronic pain, infection, and in severe cases, amputation of the limb.

The complications of compartment syndrome result from prolonged ischemia (lack of blood flow) to the muscles and nerves within the affected compartment. The severity of complications relates directly to the duration of elevated compartment pressure before treatment.

Volkmann's Ischemic Contracture

Volkmann's ischemic contracture is the most recognized long-term complication of compartment syndrome, particularly affecting the forearm. When muscle tissue dies due to ischemia, it is replaced by fibrous scar tissue. This scar tissue contracts (shortens) over time, pulling the joints into a fixed position that cannot be corrected even with physical therapy.

In the classic forearm Volkmann's contracture, the wrist becomes fixed in flexion (bent down), the fingers are curled, and the thumb is pulled across the palm. The condition is painless but causes severe functional impairment. Treatment options are limited once contracture has developed and may include tendon lengthening surgery, muscle-tendon transfers, or in severe cases, joint fusion in a functional position.

Nerve Damage

Nerves are highly sensitive to ischemia and are often permanently damaged by compartment syndrome. Depending on which compartment is affected, patients may experience:

• Permanent numbness in areas supplied by the affected nerves
• Chronic weakness of muscles controlled by damaged nerves
• Foot drop (inability to lift the foot) if the anterior compartment of the leg is affected
• Chronic pain or uncomfortable sensations (neuropathic pain)

Rhabdomyolysis and Kidney Failure

When muscle tissue dies, it releases large amounts of myoglobin (a muscle protein) into the bloodstream. This condition is called rhabdomyolysis. Myoglobin is toxic to the kidneys and can cause acute kidney failure. Patients with significant rhabdomyolysis require aggressive intravenous fluid therapy and monitoring of kidney function. Some may temporarily require dialysis.

Amputation

In the most severe cases of compartment syndrome - particularly when treatment is significantly delayed (more than 12-24 hours) - the damage may be so extensive that the limb cannot be salvaged. Amputation may be necessary if the limb becomes non-functional, chronically infected, or poses an ongoing risk to the patient's life due to ongoing muscle breakdown.

Infection

Dead muscle tissue is susceptible to infection. Patients with significant muscle necrosis may develop serious infections requiring additional surgeries to remove dead tissue (debridement) and prolonged antibiotic treatment.

Can Compartment Syndrome Be Prevented?

Compartment syndrome cannot always be prevented, but risk can be reduced through proper cast and bandage application, careful monitoring of at-risk patients, prompt treatment of fractures, and patient education about warning signs. For chronic exertional compartment syndrome, gradual training progression and proper warm-up may help.

Prevention strategies focus on identifying at-risk situations and ensuring early recognition and treatment:

For Healthcare Providers

• Proper cast application - ensure adequate padding, avoid circumferential casting immediately after injury when swelling is expected
• Close monitoring - frequent neurovascular checks in patients with high-risk injuries
• Patient education - clearly explain warning signs that require immediate return
• Low threshold for intervention - split or remove casts if any concern about compartment syndrome
• Positioning during surgery - avoid prolonged pressure on limbs during lengthy procedures

For Patients

• Know the warning signs - increasing pain, numbness, or inability to move fingers/toes after injury or cast placement
• Seek care promptly - do not delay if concerning symptoms develop
• Follow elevation instructions - but do not elevate significantly above heart level
• Avoid constrictive items - remove jewelry, watches from injured limbs before swelling develops

For Athletes (CECS Prevention)

• Gradual training progression - avoid sudden increases in training volume or intensity
• Proper warm-up - adequate warm-up before intense activity
• Appropriate footwear - well-fitted shoes appropriate for the activity
• Cross-training - vary activities to avoid overloading specific muscle groups
• Address symptoms early - don't push through significant exercise-related leg pain

What Is the Outlook for Compartment Syndrome?

The prognosis for compartment syndrome depends critically on how quickly treatment is received. With fasciotomy within 6 hours, most patients recover fully. Delays beyond 6-12 hours significantly increase the risk of permanent complications. Chronic exertional compartment syndrome has an excellent prognosis with appropriate treatment.

For acute compartment syndrome, timing of treatment is the primary determinant of outcome:

• Fasciotomy within 6 hours: Excellent prognosis, most patients achieve full or near-full recovery
• Fasciotomy at 6-12 hours: Variable outcomes, some patients develop permanent weakness or sensory changes
• Fasciotomy after 12 hours: High likelihood of permanent complications including contracture, weakness, numbness
• No treatment beyond 24-48 hours: Likely non-functional limb, high risk of amputation

Recovery from fasciotomy involves multiple stages. Initial wound healing takes 2-4 weeks (longer if skin grafting is required). Physical therapy to regain strength and range of motion typically continues for 3-6 months. Full recovery may take 6-12 months, and some patients continue to improve for up to 2 years.

For chronic exertional compartment syndrome, the prognosis is generally excellent. Conservative management allows many patients to continue modified activities without surgery. For those who require surgical fasciotomy, approximately 80-90% return to their previous activity level, though full recovery may take 3-6 months.