What are the diagnostic compartment pressures for chronic lower extremity compartment syndrome?

Diagnostic Compartment Pressures for Chronic Lower Extremity Compartment Syndrome

For chronic exertional compartment syndrome (CECS) of the lower extremity, diagnostic compartment pressures are considered abnormal when resting pressures are ≥10 mmHg and/or post-exercise pressures are ≥30 mmHg. 1, 2

Pressure Measurement Techniques and Values

Normal vs. Abnormal Pressure Values

• Resting pressure:

  • Normal: <10 mmHg
  • Abnormal: ≥10 mmHg 1

• Post-exercise pressure:

  • Normal: <25-30 mmHg at 5 minutes post-exercise
  • Abnormal: ≥30 mmHg 2

Measurement Methodology

• Direct compartment pressure measurement is the gold standard for diagnosis 3
• Measurement techniques include:
  • Traditional needle manometry
  • Multiparameter monitors (typically used for arterial blood pressure)
  • Dedicated transducer-tipped intracompartmental pressure monitors 3

Technical Considerations

• Equipment selection affects accuracy:
  • Using an 18-G needle may overestimate compartment pressure by up to 18 mmHg compared to slit catheters or side-ported needles 3
  • Slit catheters are preferred for more accurate measurements 3
• Measurements should be taken in all relevant compartments of the affected limb 3
• Single or continuous pressure monitoring may be performed 3

Compartment-Specific Considerations

Most Commonly Affected Compartments

• Anterior compartment (most frequent)
• Lateral compartment
• Deep posterior compartment
• Superficial posterior compartment 4, 2

Case Example of Abnormal Pressures

In a documented case of bilateral CECS, the following resting pressures were measured 5:

• Deep posterior: 36 mmHg (abnormal)
• Superficial posterior: 36-38 mmHg (abnormal)
• Anterior: 25 mmHg (abnormal)

After successful treatment, pressures normalized to:

• Deep posterior: 11 mmHg
• Superficial posterior: 8 mmHg
• Anterior: 19 mmHg
• Lateral: 10 mmHg 5

Clinical Correlation

Predictive Clinical Signs

The most predictive clinical signs for CECS include:

• Muscle hardness
• Muscle hernia after exercise
• Absence of pain at rest
• Pain recurrence with the same exercise 2

When both muscle hardness and post-exercise muscle hernia are present, they correctly identify 88.6% of CECS cases 2.

Diagnostic Algorithm

1. Obtain clinical history focusing on exercise-induced pain that resolves with rest
2. Perform physical examination looking for muscle hardness and herniation
3. Conduct exercise challenge (typically treadmill running) until symptoms occur
4. Measure compartment pressures immediately post-exercise and at 5-minute intervals
5. Diagnose CECS if:
   • Resting pressure ≥10 mmHg, and/or
   • Post-exercise pressure ≥30 mmHg at 5 minutes 1, 2

Treatment Implications

The accurate diagnosis of CECS through compartment pressure measurement is crucial for determining appropriate treatment. When pressures confirm CECS, surgical fasciotomy is highly effective, with success rates of up to 92% for anterior compartment release 1. However, deep posterior compartment release may have less predictable outcomes 4.

Common Pitfalls

• Using inappropriate needle size can lead to pressure overestimation 3
• Relying solely on clinical signs without pressure measurement can lead to misdiagnosis 3
• Failure to measure all potentially affected compartments may miss multicompartmental CECS 4
• Not distinguishing between acute compartment syndrome (requiring immediate fasciotomy) and chronic exertional compartment syndrome (which may be managed differently) 3