Definition
Acute compartment syndrome occurs when pressure within a closed osteofascial compartment compromises tissue perfusion. Muscle and nerve injury can become irreversible if decompression is delayed.
Causes
Common causes include:
- tibial and forearm fractures
- high-energy crush injury
- reperfusion after vascular injury
- bleeding into a closed compartment
- constrictive casts or dressings
- burns
- prolonged limb compression
An open fracture does not exclude compartment syndrome.
Common causes include:
- tibial fractures
- forearm fractures
- crush injury
- reperfusion
- bleeding disorders or anticoagulation
- tight casts/dressings
- burns
- prolonged compression
An open fracture does not exclude compartment syndrome.
Diagnosis
The diagnosis is primarily clinical in an alert patient.
Early findings:
- escalating pain inconsistent with the apparent injury
- increasing analgesic requirement
- pain on passive stretch of muscles in the involved compartment
- tense swelling
- paraesthesia may develop
Weakness, paralysis and loss of pulses are late findings. A palpable pulse therefore does not rule out compartment syndrome.
Pressure measurement
Pressure measurement is most useful when the examination is unreliable, for example in an unconscious, sedated or very young patient. Interpret pressure with the patient's blood pressure and overall clinical picture rather than using one isolated value.
A commonly used concept is delta pressure:
diastolic blood pressure − compartment pressure
A persistently small pressure difference in a compatible clinical setting supports decompression.
Absolute pressure values can be misleading if blood pressure is ignored.
A commonly used concept is the delta pressure: diastolic blood pressure minus compartment pressure.
A persistently low delta pressure supports the diagnosis in the appropriate clinical context. Measurement complements, rather than replaces, clinical judgement.
Immediate measures
While preparing for definitive treatment:
- remove or split constrictive dressings and casts
- correct hypotension and hypoxia
- keep the limb approximately at heart level rather than markedly elevated
- reassess promptly
Fasciotomy
Established acute compartment syndrome requires urgent complete decompression of all affected compartments.
In the leg, the standard two-incision technique can decompress the anterior, lateral, superficial posterior and deep posterior compartments. In the forearm, release must address the involved volar and/or dorsal compartments and the carpal tunnel when indicated.
After fasciotomy
- inspect muscle viability
- leave swollen wounds open initially
- return for reassessment and debridement when required
- close directly, use delayed closure techniques, or graft once swelling has resolved
Late fasciotomy after established muscle necrosis may increase infection and systemic complications; treatment then requires individualized senior decision-making.
Pathophysiology
Acute compartment syndrome occurs when pressure within a closed fascial compartment rises enough to compromise tissue perfusion.
The critical problem is reduced perfusion pressure, influenced by both compartment pressure and systemic blood pressure. A hypotensive patient can therefore develop ischaemia at a lower absolute compartment pressure.
Clinical diagnosis
The most useful early features are:
- escalating pain
- pain disproportionate to apparent injury
- pain on passive stretch
- tense swollen compartment
- increasing analgesic requirement
Sensory change and motor weakness are later findings. Pulselessness is very late and should not be used as a screening criterion.
In sedated, unconscious or unreliable patients, clinical diagnosis is more difficult and pressure monitoring may have a larger role.
Immediate action
Remove all external constriction:
- split casts
- release circumferential dressings
- keep the limb around heart level rather than markedly elevated
If compartment syndrome is diagnosed, urgent fasciotomy is required.
Fasciotomy principles
All involved compartments must be completely decompressed.
For the leg this usually means release of all four compartments through a recognised technique.
Muscle viability is assessed at surgery. Wounds are generally left open initially and re-inspected, with delayed closure or grafting when swelling allows.
Late sequelae
Delayed diagnosis can produce:
- muscle necrosis
- nerve injury
- contracture
- renal injury from rhabdomyolysis
- infection
- amputation
FRCS synthesis
Do not wait for the “five Ps”. The exam-level message is pain and passive-stretch pain are early; neurological deficit and absent pulse are late.