A 28-year-old male presents to the emergency department 6 hours after a crush injury to the right leg sustained in a road traffic accident. He complains of severe pain in the anterior compartment of the leg that is disproportionate to the clinical findings and is not relieved by analgesics. On examination, pain is elicited on passive dorsiflexion of the foot. Compartment syndrome is suspected. Which investigation is the gold standard for confirming the diagnosis?

Explanation

## Diagnosis of Compartment Syndrome ### Gold Standard Investigation **Key Point:** Compartment pressure measurement using needle manometry (or wick catheter manometry) is the gold standard and most specific investigation for confirming acute compartment syndrome. ### Why Compartment Pressure Measurement? Compartment syndrome is a clinical diagnosis supported by objective pressure measurement. The investigation directly measures intra-compartmental pressure, which is the pathophysiological hallmark of the condition. ### Diagnostic Criteria | Pressure Threshold | Clinical Significance | |---|---| | > 30 mmHg (absolute) | Diagnostic in most cases | | Within 30 mmHg of diastolic BP | Concerning; requires close monitoring | | > 40 mmHg | Definitive indication for fasciotomy | **High-Yield:** The delta pressure (diastolic BP − compartment pressure) is more reliable than absolute pressure. A delta pressure < 30 mmHg is highly suggestive of compartment syndrome and warrants surgical decompression. ### Technique 1. Needle manometry: Quick, bedside, single-point measurement 2. Wick catheter: Continuous monitoring, more accurate 3. Slit catheter: Alternative continuous monitoring method ### Clinical Context **Clinical Pearl:** In this case, the classic triad of compartment syndrome is present: - Pain out of proportion to clinical findings - Pain on passive stretch (passive dorsiflexion causing pain in anterior compartment) - Severe, progressive pain despite analgesia These clinical signs warrant immediate pressure measurement and, if elevated, urgent fasciotomy without waiting for imaging confirmation. **Warning:** Do NOT delay fasciotomy waiting for imaging studies. Compartment syndrome is a surgical emergency — tissue necrosis begins within 6–8 hours of onset. Clinical suspicion + elevated compartment pressure = indication for immediate fasciotomy. ### Why Imaging Is Not Gold Standard - MRI and ultrasound can show edema and muscle changes but are NOT specific for compartment syndrome - They are time-consuming and delay definitive treatment - They do not directly measure the pathophysiological abnormality (elevated pressure) [cite:Campbell's Operative Orthopaedics 13e Ch 56]