Compartment Syndrome — Pressure Criteria

Compartment syndrome is a limb threatening condition caused by increased pressure within a closed fascial compartment leading to impaired tissue perfusion. When intracompartmental pressure rises beyond capillary perfusion pressure, circulation to muscles and nerves becomes compromised. If untreated this results in ischemia, tissue necrosis, permanent functional deficit and sometimes limb loss.

The condition is considered a true orthopaedic emergency because irreversible muscle and nerve damage can occur within a few hours. Early recognition and urgent decompression are essential to prevent permanent disability.

Compartment syndrome most commonly occurs after trauma particularly fractures of long bones. The tibial shaft fracture is the most frequently associated injury. However the syndrome may also occur after soft tissue injury, burns, reperfusion injury following vascular repair or external compression from casts and bandages.

Any anatomical compartment surrounded by non compliant fascia can develop this syndrome. The most commonly involved anatomical sites include the leg, forearm, thigh, foot, hand and gluteal region.

Compartments consist of groups of muscles, nerves and vessels surrounded by inelastic fascia. Because the fascia has minimal capacity to expand any increase in volume inside the compartment leads to a rapid increase in pressure.

Leg Compartments

Compartment syndrome develops when intracompartmental pressure increases to a level that exceeds capillary perfusion pressure.

• Increase in compartment volume due to swelling or bleeding
• Rigid fascia prevents expansion
• Intracompartmental pressure rises
• Venous outflow obstruction occurs
• Capillary perfusion decreases
• Tissue ischemia develops

Diagnosis of compartment syndrome is primarily clinical. The classic teaching describes six cardinal signs.

• Pain on passive stretch is the earliest reliable sign
• The compartment feels tense and firm
• Distal pulses may remain present

Delta pressure equals diastolic blood pressure minus compartment pressure.