Acute Compartment Syndrome: The Clinical Guide

Acute Compartment Syndrome (ACS) is an orthopaedic emergency characterized by elevated pressure within a closed osteofascial compartment, leading to reduced capillary perfusion. If untreated, it causes irreversible muscle necrosis and nerve damage (Volkmann's Ischemic Contracture).

It is a diagnosis that requires vigilance, courage to act, and precise surgical execution.

Pathophysiology: The Vicious Cycle

ACS is a perfusion problem, not a pressure problem per se.

1. Insult: Fracture, Crush, or Reperfusion injury causes edema/bleeding.
2. Pressure Rise: The fascia is unyielding. Volume increases -> Pressure increases.
3. Venous Collapse: When compartment pressure > venous pressure, veins collapse. Outflow stops.
4. Congestion: Arterial inflow continues, but blood cannot leave. Hydrostatic pressure skyrockets.
5. Ischemia: Capillaries collapse. Muscle and nerve death begins.

Visual Element: Diagram of the "Vicious Cycle of ACS" showing the feedback loop of edema -> pressure -> venous occlusion -> more edema.

Diagnosis: Clinical vs. Monitoring

Clinical Diagnosis (The Conscious Patient)

• Pain out of Proportion: The patient requires escalating opioids. The pain is relentless, deep, and burning.
• Pain with Passive Stretch: The most sensitive sign. Stretching the muscle (e.g., extending the toes for the anterior compartment) increases compartment pressure and elicits severe pain.
• Palpation: The compartment feels "woody" or tense.

The Myth of the 5 Ps:

• Pallor: Rare.
• Paresthesia: A sign of nerve ischemia (too late).
• Paralysis: A sign of muscle death (too late).
• Pulselessness: NEVER WAIT FOR THIS. Arterial pressure (120mmHg) > Compartment Pressure (40mmHg). A pulseless limb is an arterial injury, not just compartment syndrome.

Pressure Monitoring (The Unconscious Patient)

In obtunded or polytrauma patients, clinical exam is impossible. Use a manometer (e.g., Stryker device).

• Absolute Pressure: Historically >30mmHg was the cutoff. This is flawed (high false positives in hypotensive patients).
• Delta Pressure (ΔP): The Gold Standard.
  • Formula: ΔP = Diastolic BP - Compartment Pressure.
  • Threshold: ΔP < 30 mmHg is diagnostic of ACS.
  • Example: Patient BP 120/70. Compartment Pressure 45. ΔP = 25. FASCIOTOMY.

Surgical Technique: Leg Fasciotomy

The lower leg has 4 compartments: Anterior, Lateral, Superficial Posterior, Deep Posterior. You must release all four.

The Two-Incision Technique:

1. Lateral Incision:

   • Location: 2cm anterior to fibula shaft, halfway between knee and ankle. Length ~15-20cm.
   • Action: Identify the Intermuscular Septum.
   • Anterior Release: Open fascia anterior to the septum. Watch for Superficial Peroneal Nerve (SPN) exiting distally.
   • Lateral Release: Open fascia posterior to the septum.

2. Medial Incision:

   • Location: 2cm posterior to the medial border of the tibia.
   • Action: Incise Saphenous fascia (Superficial Posterior compartment).
   • Deep Release: Retract Gastrocnemius/Soleus. Identify the flexor digitorum longus (FDL) and Tibialis Posterior. Incise the fascia covering them (Deep Posterior Compartment). Release the Soleal Bridge proximally.

Clinical Trap: Failing to release the Deep Posterior Compartment is the most common error. You must detach the soleus origin from the tibia to fully decompress the deep space.

Post-Operative Management

• Wound Management: Leave wounds open. Apply a Negative Pressure Wound Therapy (VAC) sponge or "Shoelace" vessel loops to prevent skin retraction.
• Second Look: Return to theatre at 48-72 hours. Debride any necrotic muscle.
• Closure: Delayed Primary Closure (DPC) if swelling subsides. Split Skin Graft (SSG) if tension remains.

Complications

• Rhabdomyolysis: Muscle breakdown releases Myoglobin -> Renal Failure. Hydrate aggressively.
• Volkmann's Contracture: Fibrosis of necrotic muscle leads to claw deformities.
• Infection: Open wounds carry risk.

Conclusion

Compartment syndrome is unforgiving. Time is muscle.

• Suspect it: In any fracture with escalating pain.
• Measure it: Use Delta P < 30 mmHg.
• Release it: 4 compartments, full length skin incisions.

References

1. McQueen, M. M., & Court-Brown, C. M. (1996). "Compartment monitoring in tibial fractures. The pressure threshold for decompression." JBJS.
2. Whitesides, T. E., et al. (1975). "Tissue pressure measurements as a determinant for the need of fasciotomy." CORR.