A 25-year-old male sustains a closed tibial shaft fracture treated with intramedullary nailing. 48 hours later he develops worsening pain out of proportion, pain on passive toe extension, and a tense calf. Compartment pressure is measured at 42 mmHg. In a normotensive patient, this finding:

• A Mandates immediate four-compartment fasciotomy as the delta pressure is <30 mmHg ✓
• B Requires observation for 6 hours before intervention
• C Is consistent with normal post-operative swelling; no intervention needed
• D Requires elevation and ice application for 12 hours

Explanation

Acute compartment syndrome is diagnosed clinically; compartment pressure is confirmatory. The threshold for fasciotomy is: absolute pressure >30 mmHg OR delta pressure (diastolic BP minus compartment pressure) <30 mmHg. In a normotensive patient (e.g., diastolic BP 70 mmHg), delta pressure = 70 - 42 = 28 mmHg (< 30 mmHg), mandating immediate four-compartment fasciotomy of the leg. Delay beyond 6 hours causes irreversible muscle necrosis, volkmann's ischemia, and nerve injury. Post-IMN compartment syndrome occurs in 1-9% of cases.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.