What is the first sign of compartment syndrome?

First Sign of Compartment Syndrome

Pain out of proportion to the injury or clinical situation is the earliest sign of developing acute compartment syndrome (ACS). 1

Clinical Presentation of Compartment Syndrome

Compartment syndrome develops when pressure increases within a closed osteofascial compartment, leading to decreased tissue perfusion and potential ischemia. The classic signs and symptoms include:

Early Signs (Most Important for Early Detection)

• Pain out of proportion to the injury - considered the earliest and most reliable warning sign 1
• Pain on passive stretch of the affected muscle compartment - regarded by some as the most sensitive early sign 1
• Increasing firmness/tension of the compartment - as intracompartmental pressure rises 1
• Paresthesia (sensory changes) - resulting from nerve ischemia 1

Late Signs (Indicate Significant Tissue Damage)

• Paralysis (motor deficits) 1
• Pulselessness 1
• Pallor 1
• Decreased temperature (coldness) 1

Diagnostic Challenges

The diagnosis of compartment syndrome presents several challenges:

• Clinical signs alone have low sensitivity and positive predictive value but high specificity and negative predictive value 1
• In isolation, severe pain gives only approximately 25% chance of correctly diagnosing ACS 1
• The presence of both severe pain and pain on passive stretch increases positive predictive value to 68% 1
• When pain, pain on passive stretch, and paralysis are all present, positive predictive value reaches 93%, but paralysis indicates irreversible muscle ischemia may have already occurred 1
• Palpation of the suspected compartment is unreliable in isolation (sensitivity 54%, specificity 76% in children) 1

High-Risk Populations

Certain populations have increased risk of developing compartment syndrome:

• Young men under 35 years with tibial fractures 1
• Patients with fractures (especially tibial shaft fractures) 1
• Patients with crush injuries or high-energy trauma 1
• Patients with vascular injuries or burns 1
• Patients on anticoagulation 1

Management Approach

When compartment syndrome is suspected:

• Maintain a high index of suspicion in at-risk patients 1, 2
• Remove any constrictive dressings, casts, or splints 2
• Position the limb at heart level (not elevated) 1
• Measure compartment pressures if diagnosis remains in doubt, particularly in obtunded or uncooperative patients 1
• Arrange urgent surgical consultation for fasciotomy when ACS is diagnosed 1, 3

Important Pitfalls to Avoid

• Waiting for late signs - pallor, pulselessness, and paralysis indicate significant tissue damage has already occurred 1
• Relying solely on palpation - physical examination alone is unreliable for diagnosis 1
• Delaying diagnosis in obtunded patients - these patients cannot report pain and require more vigilant monitoring and earlier compartment pressure measurement 1
• Missing ACS in patients without fractures - compartment syndrome can occur with soft tissue injuries alone 1
• Elevating the limb excessively - this can further decrease perfusion pressure 1

Early recognition of pain out of proportion to injury, followed by prompt surgical intervention when indicated, is essential to prevent the devastating consequences of untreated compartment syndrome, including tissue necrosis, permanent functional impairment, and in severe cases, systemic complications such as renal failure.