Definition
Compartment syndrome refers to the elevation of interstitial pressure within a closed compartment of the human body that results in microvascular compromise, tissue ischaemia and necrosis.
Pathology
A compartment syndrome is the build-up of fluid within a body compartment, which may occur in any body region with the following clinical manifestations: head (increased intracranial pressure), chest (tension pneumothorax), heart (pericardial tamponade), abdomen (intraabdominal compartment), extremities (compartment syndromes). It is a critical condition that requires immediate medical attention and management. In the head, chest and abdomen it is life-threatening, in the extremities a limb-threatening condition.
In the upper and lower extremities, a compartment is a unit formed by a number of muscles, nerves and blood vessels that are held together by a rigid membrane of connective tissue called fascia. With tissue swelling (oedema) caused by an injury, a fracture or a surgical procedure the pressure within the tissues increasingly raises to exceed the venous pressure. This causes local accumulation of fluid containing toxic metabolic products that are not transported away through the venous system causing damage to the surrounding tissues.
A compartment syndrome leads to acute pain, impairment of venous and arterial blood transport and oxygenation, leading to tissue ischaemia, nerve alteration and finally death of the affected tissue. The pathology is often distinguished into an acute and chronic condition, such as Chronic Compartment Syndrome in athletes.
Acute compartment syndrome develops rapidly thus requiring immediate diagnosis and management. With delay to treatment it may lead to irreversible necrosis of muscle, skin and other tissues that need to be surgically excised, leaving the patient with debilitating consequences. Chronic compartment syndrome affects mostly the lower leg and is usually less severe, in most cases easily managed conservatively.
The complications arising from a compartment syndrome are chronic pain, muscle and nerve damage, infection after surgical fasciotomy, possibly leading to limb amputation. A Volkmann contracture is a permanent limb deformity of the forearm. It occurs when a compartment syndrome remains untreated resulting in a non-functional extremity due to ischaemic consequences affecting the forearm muscles.
Causes
A compartment syndrome may develop as a result of:
Bone fracture (75% of cases) especially of the tibia, humerus, radius + ulna
Vascular injury with or without fracture
Haemorrhage
Crush injury of extremities: muscle oedema
Burn: increased capillary permeability and tissue fluid entrapment
Constricting dressing, bandage, plaster, cast, tourniquet
Blunt trauma
Abdominal surgery
Risk factors
There is a vast number of risk factors potentially leading to a compartment syndrome either in isolation or combined:
Limb fractures (1-9 % incidence of compartment syndrome)
Trauma associated with vascular injuries
Haemorrhage
Burns
Open and arthroscopic surgery
Tight dressing (bandages, plaster, cast, tourniquet)
Deep vein thrombosis (DVT)
Anticoagulation therapy (haemophilia)
Athletes and soldiers performing exercise causing muscle microinjuries (also named chronic exertional compartment syndrome)
Cannulisation pumps for fluid or chemotherapy infusion
Use of injectable anabolic substances e.g. steroids
Drug and alcohol abuse
Symptoms
The symptoms of a compartment syndrome are divided into early, easily treatable signs and late symptoms that are often irreversible causing detrimental consequences such as limb amputation.
Initial signs
Disproportional pain relative to injury
Severe pain at rest
Prolonged substantial swelling
Increasing pain with muscle stretching
Tight tissues at touch
Tingling, burning sensation
Late signs
Absent pulse
Sudden cessation of pain
Appearance of skin demarcation
Loss of sensation (numbness)
Paralysis
Diagnosis
When a patient presents with traumatic injuries, swelling or a suspected fracture(s) the examining physician should always consider the possibility of an underlying compartment syndrome at the time or potentially developing in future. For a thorough evaluation, it is critical to remove bandages, plasters or any material covering the affected area.
Physical examination determines limb/tissue tightness, skin colour, presence of swelling, pulses, changes in sensation, level of pain at rest as well as with stretching and movement all of, which is compared to the healthy side (limb). Beside the clinical evaluation, a compartment syndrome is diagnosed with the measurement of compartment pressure with specific devices that should always be available in the Emergency Room.
Muscle pressure is normally up to 15 mmHg, increased between 25 – 30 mmHg and manifests as a compartment syndrome if over 45 mmHg. It is important to repeat all diagnostic parameters every 4 hours during the first day of admission because 4-8 hours post onset, the ischaemic changes become irreversible. Particular care should be given to patients with bleeding disorders and coagulopathy.
Laboratory tests include measurement of muscle proteins (creatine-phospho-kinase, CPK) in blood to detect life-threatening rhabdomyolysis and increase of muscle protein myoglobin in the urine (myoglobinuria), both factors indicative of muscle breakdown as a result of the increased interstitial pressure and ischaemia. Complete blood count is recommended to rule out infections or other pathologies (necrotising fasciitis). X-ray, CT or MRI scans are advised to detect fractures and soft tissue injuries.
Treatment
Non-operative
In the acute phase following the diagnosis when symptoms are not severe, conservative treatment of a compartment syndrome includes:
Removing any dressing, plaster, etc
Limb elevation to heart level
Ice pads
Analgesia
Frequent clinical monitoring of symptoms at 4 hour intervals
Repeated measurement of compartment pressure
Hyperbaric oxygen therapy to increase blood oxygenation and achieve hyperoxic vasoconstriction to attenuate tissue oedema.
Surgical treatment
If despite conservative treatment the compartment pressure increases to levels over 30 – 45 mmHg, the patient requires urgent surgery. Fasciotomy is the procedure of tissue decompression used to open the fascia surrounding the compartments and release the oedematous muscle, restore blood perfusion and prevent ischaemic damage. Then, if present, a fracture is reduced accordingly. The wound is normally kept open and a second look (procedure) is repeated multiple times as required. Vacuseals are often applied to temporally cover the wound and create a negative pressure to draw the excess interstitial fluid out of the affected tissue. The compartment is closed through stages and may require a skin graft to close the skin defect.
Rehabilitation
The rehabilitation following a compartment syndrome is slow as the function of the affected limb may return if at all gradually. In case of lower extremity the patient will:
Avoid full weight bearing
Use crutches
At early stage: gentle exercises to restore flexibility and range of movement of all joints of the affected lower extremity
At later stage: vigorous exercises to increase muscle tone and strength
Occupational therapy is useful in case of debilitating decompressive surgery as it requires a longer rehabilitation.
Prevention
Preventing a compartment syndrome requires a close monitoring of patients with any injury or surgery. A medical practitioner should always repeat frequently the diagnostics to detect the earliest symptoms of a compartment syndrome to allow for tempestive treatment and avoid detrimental complications.
In case of chronic compartment syndrome in cyclists, runners and other sports groups, it is recommended to perform regularly muscle stretch exercises, soft tissue massage, and biomechanical correction if necessary.