Compartment syndrome occurs when increased pressure within an osseofascial compartment reduces blood flow, causing ischemia and potential tissue necrosis. It is often caused by fractures, bleeding, edema, or tight casts/dressings. Left untreated, it leads to irreversible muscle and nerve damage within 6 hours. Early diagnosis by measuring compartment pressures and treatment through fasciotomy decompression of the compartment is crucial to prevent necrosis.

1. COMPARTMENT SYNDROME
Fractures of the arm or leg can give rise to severe
ischaemia, even if there is no damage to a major vessel.
Bleeding, oedema or inflammation (infection) may
increase the pressure within one of the osseofascial
compartments; there is reduced capillary flow, which
results in muscle ischaemia, further oedema, greater
pressure and yet more profound ischaemia – a vicious
circle that ends, after 6 hours or less, in necrosis of
nerve and muscle within the compartment. Nerve is
capable of regeneration but muscle, once infarcted, can
never recover and is replaced by inelastic fibrous tissue
(Volkmann’s ischaemic contracture). A similar cascade
of events may be caused by swelling of a limb inside a
tight plaster cast (Figure 23.29).
Clinical features
High-risk injuries are fractures of the elbow, forearm
bones, proximal third of the tibia, and also multiple
fractures of the hand or foot, crush injuries and
circumferential burns. Other precipitating factors are
operation (usually for internal fixation) or infection.
The classic features of ischaemia are the five Ps:
• Pain
• Paraesthesia
• Pallor
• Paralysis
• Pulselessness.
However, in compartment syndrome the ischaemia
occurs at the capillary level, so pulses may still be felt
and the skin may not be pale! The earliest of the
‘classic’ features is severe pain (or a ‘bursting’
sensation) and this may be the only feature seen. Altered
sensibility and paresis (or more usually, weakness in
active muscle contraction) may also occur. Skin
sensation should be carefully and repeatedly checked.
Ischaemic muscle is highly sensitive to stretch. If the
limb is unduly painful, swollen or tense, the muscles
(which may be tender) should be tested by stretching
them. When the toes or fingers are passively
hyperextended, there is increased pain in the calf or
forearm. Confirmation of the diagnosis can be made by
measuring the intracompartmental pressures. The need
for early diagnosis is so important that some surgeons
advocate the use of continuous compartment pressure
monitoring for high-risk injuries (e.g. fractures of the
tibia and fibula) and especially for forearm or leg
fractures in patients who are unconscious. A split
catheter is introduced into the compartment and the
pressure is measured close to the level of the fracture. A
differential pressure (ΔP) – the difference between
diastolic pressure and compartment pressure – of less
than 30 mmHg (4.00 kilopascals) is an indication for
immediate compartment decompression.
Treatment
The threatened compartment (or compartments) must
be promptly decompressed. Casts, bandages and
dressings must be completely removed – merely
splitting the plaster is utterly useless – and the limb
should be nursed flat (elevating the limb causes a further
decrease in end capillary pressure and aggravates the
muscle ischaemia). The ΔP should be carefully
monitored; if it falls below 30 mmHg, immediate open
fasciotomy is performed. Compartment syndrome is,
however, a clinical diagnosis and, if the surgeon
believes there is a compartment syndrome present,
fasciotomy is justified even if a predetermined pressure
threshold has not been reached or the facility to measure
pressure is not immediately available. If the clinical
signs are ‘soft’, the limb should be examined at 30
minute intervals and, if there is no improvement within
2 hours of splitting the dressings, fasciotomy should be
performed. Muscle will be dead after 4–6 hours of total
ischaemia – there is no time to lose! In the case of the
leg, ‘fasciotomy’ means opening all four compartments
through medial and lateral incisions (see Figure 23.22).
The wounds should be left open and inspected 2 days
later: if there is muscle necrosis, debridement can be
carried out; if the tissues are healthy, the wounds can be
sutured (without tension) or skin-grafted.