🚨 Acute Compartment Syndrome (ACS) = orthopaedic emergency requiring immediate fasciotomy.
❌ If untreated, leads to irreversible muscle & nerve necrosis, limb contractures, rhabdomyolysis, renal failure, or amputation.
⏳ Critical window: ~6 hours before permanent damage occurs.

💡 Clinical pearl: Pain out of proportion + pain on passive stretch = the most reliable early signs.

⚙️ Pathophysiology

📈 Trauma or swelling raises intracompartmental pressure within a rigid fascial boundary.
🩸 Capillary perfusion pressure drops → muscle ischaemia → oedema → further ↑ pressure → vicious cycle of tissue hypoxia.
⚠️ Nerve injury occurs earlier than muscle necrosis (ischaemic neuropathy).

📌 Causes

🦴 Fractures (tibia, forearm = most common).
🤕 Soft tissue trauma (crush injuries, contusions, reperfusion after ischaemia).
🩸 Vascular injury/bleeding (trauma, surgery, anticoagulation).
🩻 External compression (tight casts, splints, bandages, prolonged positioning).
🔥 Circumferential burns causing restrictive eschar.

🩺 Clinical Presentation

😣 Severe, progressive pain, disproportionate to injury.
↔️ Pain exacerbated on passive stretch (e.g., dorsiflexing toes with tibial fracture).
🔔 Tense, “wood-like” compartment on palpation.
Late signs: paraesthesia, paralysis, pallor, pulselessness → indicate irreversible damage.

📝 5 Ps (but remember only Pain is early): Pain ✅ | Paraesthesia ❌ | Paralysis ❌ | Pallor ❌ | Pulselessness ❌

🧾 Differentials

Arterial occlusion (embolus, thrombosis).
Deep vein thrombosis (DVT).
Severe cellulitis/myositis.
Peripheral neuropathy (e.g., diabetic foot pain).

🔎 Investigations

🔍 Clinical diagnosis — do not delay.
📊 Compartment pressure monitoring:
- >30 mmHg = diagnostic threshold.
- ΔP (diastolic BP – compartment pressure) <30 mmHg also significant.
🧪 Bloods: CK & myoglobin (to assess rhabdomyolysis), U&E for AKI risk.

⚡ Management

📞 Immediate orthopaedic referral — time-critical.
🔓 Remove external compression: split casts, dressings.
💨 O₂ + 💧 IV fluids to optimise tissue perfusion.
🔪 Emergency fasciotomy: release all compartments at risk (commonly 4 in the leg, 2 in forearm).
🩹 Post-op: leave wounds open, apply VAC dressings; may need delayed closure or skin grafting.

🌟 Key takeaway: A present pulse does not rule out ACS — always trust pain + passive stretch. Document neurovascular exams regularly.

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Acute Compartment Syndrome

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