Overview
Definition:
Fasciotomy for acute compartment syndrome (ACS) of the lower limb is a surgical procedure involving the division of fascial compartments to relieve elevated interstitial pressure, restore blood flow, and prevent irreversible muscle and nerve damage.
Epidemiology:
ACS is most commonly associated with fractures (especially tibia and femur) and crush injuries, but also seen after reperfusion injury, burns, and prolonged immobilization
Incidence varies widely depending on the cause, but fractures of the lower leg carry a significant risk.
Clinical Significance:
Untreated ACS can lead to profound functional deficits, including muscle infarction, Volkmann's ischemic contracture, chronic pain, nerve damage, and ultimately, limb loss
Early recognition and prompt surgical intervention are critical for limb salvage and functional recovery.
Clinical Presentation
Symptoms:
Severe, disproportionate pain out of proportion to the apparent injury
Pain that is worsened by passive stretching of the muscles within the affected compartment
Paresthesia or numbness in the distribution of nerves traversing the affected compartment
Weakness or paralysis of muscles within the compartment (late sign).
Signs:
The classic "5 Ps" of compartment syndrome: Pain (out of proportion), Pallor (late), Pulselessness (late), Paresthesia, Paralysis
Palpable tenseness of the involved compartment
Decreased sensation to light touch
Weakness on active or passive movement of the digits or ankle
Ecchymosis and swelling may be present but are not specific.
Diagnostic Criteria:
There are no absolute diagnostic criteria, but a high index of suspicion coupled with objective measurement of compartment pressures is essential
A pressure of >30 mmHg, or a differential pressure (diastolic blood pressure minus compartment pressure) of <20 mmHg (Delta Pressure) is generally considered indicative of ACS, though these values should be interpreted in the clinical context.
Diagnostic Approach
History Taking:
Thorough history of trauma, including mechanism of injury, force, and any associated fractures
Time elapsed since injury
History of vascular compromise or reperfusion
Medications that could affect pain perception or coagulation
Previous musculoskeletal issues.
Physical Examination:
Systematic palpation of all compartments of the lower limb (anterior, lateral, deep posterior, superficial posterior)
Assess for tenseness and tenderness
Evaluate distal pulses (dorsalis pedis, posterior tibial)
Test sensation to light touch in the dermatomes of the superficial peroneal, deep peroneal, tibial, and sural nerves
Assess motor function of foot and toe dorsiflexion, plantarflexion, and toe extension.
Investigations:
Compartment pressure measurement is the gold standard
typically done using a digital manometer with a fine-gauge needle (e.g., 18-20 gauge) or a slit catheter
Normal compartment pressure is typically 0-10 mmHg
Imaging modalities like X-ray are useful to identify underlying fractures but do not diagnose ACS
Doppler ultrasound can assess arterial flow but does not measure compartment pressures.
Differential Diagnosis:
Peripheral nerve injury, deep vein thrombosis (DVT), cellulitis, stress fracture, fracture-related pain without compartment syndrome, tendinitis, vascular insufficiency,msk contusion.
Management
Initial Management:
Immediate cessation of any constricting dressings or casts
Elevation of the limb to the level of the heart (not above, to avoid reducing arterial inflow)
Pain control with systemic analgesics
Avoidance of aggressive fluid resuscitation that could increase interstitial edema unless hemodynamically indicated.
Medical Management:
Not a primary treatment for established ACS
Analgesia is crucial for pain management and to facilitate examination
Avoidance of medications that could mask symptoms or worsen bleeding (e.g., NSAIDs).
Surgical Management:
Urgent surgical fasciotomy is indicated when compartment pressures meet diagnostic criteria or when clinical suspicion is high
The procedure involves incising the skin and dividing the deep fascia of all affected compartments
Common fasciotomy incisions include the anterolateral approach (for anterior and lateral compartments) and the posteromedial approach (for superficial and deep posterior compartments)
The fibular head is often used as a landmark for the anterolateral incision
The number of compartments to be opened depends on the extent of injury and clinical findings
Complete division of the fascia is essential.
Supportive Care:
Close monitoring of compartment pressures post-operatively
Wound management, including leaving fasciotomy wounds open and covered with dressings or utilizing delayed primary closure/skin grafting
Physiotherapy for range of motion exercises once fasciotomy is performed and pain subsides
Infection prophylaxis and management.
Complications
Early Complications:
Infection of the fasciotomy wound, nerve injury (e.g., peroneal nerve palsy), hematoma formation, iatrogenic arterial or venous injury during fasciotomy, incomplete decompression of a compartment.
Late Complications:
Chronic pain, weakness, stiffness, contractures (e.g., foot drop, equinus deformity), nerve entrapment within scar tissue, cosmetic deformities, sensory deficits, osteoarthritis if joint is involved in initial injury.
Prevention Strategies:
Meticulous surgical technique during fasciotomy, avoiding excessive retraction, careful identification of anatomical structures
Prompt recognition and treatment of ACS
Appropriate wound care and early mobilization
Careful monitoring of compartment pressures postoperatively.
Prognosis
Factors Affecting Prognosis:
Timeliness of surgical intervention is the most critical factor
Duration of elevated compartment pressures
Extent of initial injury
Presence of associated vascular or nerve injury
Age and comorbidities of the patient
Adequacy of fasciotomy.
Outcomes:
With timely fasciotomy, limb salvage rates are high, and functional outcomes can be good
However, some degree of residual weakness, sensory deficit, or chronic pain may persist
Delayed intervention significantly increases the risk of irreversible muscle necrosis and poor functional outcome.
Follow Up:
Regular follow-up with orthopedic or trauma surgeons
Serial physical examinations to assess wound healing, nerve recovery, and muscle function
Physiotherapy is often required for extended periods
Serial compartment pressure measurements may be needed in select cases.
Key Points
Exam Focus:
The 5 Ps of compartment syndrome
Measurement of compartment pressures (absolute and differential)
Indications for fasciotomy
Anatomy of lower limb compartments and common fasciotomy incision sites (anterolateral, posteromedial)
Complications of ACS and fasciotomy
The critical time window for intervention.
Clinical Pearls:
Never rely solely on the presence of pulses
compartment pressures are paramount
Always consider ACS in any patient with lower limb trauma and disproportionate pain
Palpate for tenseness
it is a key physical finding
Perform compartment pressure measurements yourself if the situation is unclear
Document all pressure readings and clinical findings meticulously.
Common Mistakes:
Delayed diagnosis due to over-reliance on pulse checks or underestimation of pain
Inadequate fasciotomy (e.g., failure to divide all involved compartments or incomplete fascial division)
Performing fasciotomy too late, leading to irreversible damage
Treating compartment syndrome with less invasive methods when fasciotomy is indicated.