Compartment Syndrome
Compartment syndrome is an orthopaedic surgical emergency caused by raised pressure within a closed fascial compartment, leading to impaired perfusion, tissue ischaemia and eventual muscle and nerve necrosis.
Pathophysiology
Relevant anatomy:
- Skeletal muscles are arranged into compartments, which are surrounded by fascia
- Fascia is relatively inelastic / non-compliant, and cannot rapidly stretch to accommodate increased pressure
Compartment syndrome occurs when pressure rises within a closed fascial compartment. This may occur due to:
- ↑ Contents within the compartment, e.g. bleeding, oedema
- ↓ Compartment capacity, e.g. tight cast, tight dressing
This causes the following cascade:
- The fascia cannot stretch → ↑ intracompartmental pressure
- Impaired venous outflow → worsens oedema and further increases the intracompartmental pressure
- As pressure rises further, capillary perfusion and arterial inflow become compromised
- Ischaemia and eventually muscle and nerve necrosis
Causes and Risk Factors
Fractures (esp. long bone fractures) account for ~75% of all compartment syndrome causes [Ref]
- Tibial shaft fractures – most common
- Distal radial fractures – 2nd most common
- In children, it is frequently associated with supracondylar fracture of the humerus and radial / ulnar forearm fractures
Other causes: [Ref]
- Soft tissue injury
- Medical or vascular causes (e.g. reperfusion after ischaemia, vascular injury, thrombosis, bleeding disorders)
- External compression
- Tight circumferential bandages
- Improperly placed casts or splints
Risk factors: [Ref]
- Open fractures
- <35 y/o males (due to larger relative muscle mass and higher chance of being involved in high-energy trauma)
- Bleeding disorders (e.g. haemophilia)
Clinical Features
Early features of compartment syndrome:
- Altered sensation (e.g. paraesthesia, hypoaesthesia) is an early finding
- Severe pain out of proportion to the injury
- Pain on passive movement / stretching of the muscles
- Tense, “woody” muscle compartments on palpation
Any of the following should also raise suspicion of compartment syndrome:
- Pain scores not improving despite analgesia
- Increasing opiate use
- Poor response to opiates
The 5Ps are often used to learn the clinical features of compartment syndrome: pain, pulselessness, paraesthesia, paralysis and pallor.
However, apart from paraesthesia, the other Ps are generally late findings.
Pulses are normally present in compartment syndrome
- The presence or absence of a pulse is NOT an accurate indicator of compartment pressure or risk, a patient can still have a strong pulse even if the limb is severely compromised.
- Absent pulses are usually due to systemic hypotension, arterial occlusion, or vascular injury.
Complications
Local limb complications: [Ref]
- Muscle necrosis (which may require amputation)
- Nerve injury → persistent paraesthesia, numbness, or weakness
- Contractures
- Forearm compartment syndrome can cause Volkmann’s ischaemic contracture (→ fixed flexion deformity of the hand / wrist)
- Chronic pain and stiffness
- Limb deformity / loss of function
Severe muscle necrosis can also cause rhabdomyolysis, which can lead to: [Ref]
- Hyperkalaemia
- AKI (from myoglobinuria)
- Death
Assessment and Management
Immediate management for suspected clinical compartment syndrome:
- Release all circumferential dressings to skin
- Elevate the limb to heart level
- Maintain normotensive blood pressure
After initial management, re-assess after 30 min to decide subsequent actions:
- Strong clinical suspicion of compartment syndrome → surgical decompression within 1 hour
- Clinical diagnostic uncertainty (esp. if the patient has reduced level of consciousness or if regional anaesthesia has been performed) → measure compartment pressure
If the clinical picture is compatible with compartment syndrome, proceed straight to surgical decompression.
Do NOT measure intracompartmental pressure to confirm the diagnosis.
Surgical Decompression
Surgical decompression should be performed within 1 hour
Surgical decompression involves:
- Immediate open fasciotomy to decompress the compartments (the wound is typically left open for delayed closure)
- Excise any necrotic muscle
- Re-exploration at ~48 hours (or earlier if clinically indicated)
Delays in decompression can result in irreversible tissue necrosis within 6–10 hours
Compartment Pressure Measurement
Place a compartment monitor to measure intracompartmental pressure and also measure the patient’s diastolic blood pressure
- Absolute compartment pressure >40 mmHg → urgent surgical decompression
- Compartment perfusion pressure (delta pressure) <30 mmHg suggests increased risk → surgical decompression is generally indicated