Patient: 30-year-old male Presentation: Right forearm pain following motorcycle accident (90km/hr), brought to ED by ambulance, very distressed with severe pain despite analgesia Relevant history: High-speed motorcycle vs car collision, landed on outstretched hand, no loss of consciousness, no other injuries identified in primary survey, GCS 15 Examination findings:
| Test | Result | Normal Range | Interpretation |
|---|---|---|---|
| Hb | 142 g/L | 130-180 g/L | Normal |
| WCC | 12.8 ×10⁹/L | 4-11 ×10⁹/L | Mildly elevated (stress response) |
| Platelets | 312 ×10⁹/L | 150-400 ×10⁹/L | Normal |
| Creatinine | 98 μmol/L | 60-110 μmol/L | Normal |
| CK | 2,450 U/L | 30-200 U/L | Elevated (muscle injury/ischemia) |
| Lactate | 2.8 mmol/L | 0.5-2.0 mmol/L | Elevated |
| Potassium | 4.8 mmol/L | 3.5-5.0 mmol/L | Normal |
| Coagulation | Normal | - | Safe for surgery |
| Group & Hold | Complete | - | For surgery |
Image 1: AP and Lateral Right Forearm Radiographs
Radiological features:
Pressure readings:
| Compartment | Pressure | Diastolic BP | Delta P |
|---|---|---|---|
| Volar superficial | 42 mmHg | 80 mmHg | 38 mmHg |
| Volar deep | 48 mmHg | 80 mmHg | 32 mmHg |
| Dorsal | 35 mmHg | 80 mmHg | 45 mmHg |
Delta P (Diastolic - Compartment Pressure) <30 mmHg = Indication for fasciotomy
What is compartment syndrome and what are the clinical features to recognise it?
What are the forearm compartments and what structures are at risk?
How do you measure compartment pressures and what are the indications for fasciotomy?
Describe your surgical technique for forearm fasciotomy.
The patient returns at 4 months with progressive forearm pain and stiffness. What is the diagnosis and management?
At 18 months post-operatively, the patient returns with new forearm pain after lifting a 5kg bag. What is the likely diagnosis and management?
This pattern suggests Forearm Compartment Syndrome:
Early Signs (Act on These):
| Sign | Why Important |
|---|---|
| Pain out of proportion | Most sensitive early sign |
| Pain with passive stretch | Earliest physical finding |
| Tense compartment | Direct evidence of increased pressure |
| Paraesthesia | Nerve ischemia |
Late Signs (Don't Wait for These):
| Sign | Significance |
|---|---|
| Paralysis | Irreversible muscle damage |
| Pulselessness | Very late, damage already done |
| Pallor | Severe ischemia |
Q: "This patient is intubated and sedated after polytrauma. How do you diagnose compartment syndrome?"
In obtunded patients:
Approach: Have a very low threshold for fasciotomy in unconscious patients with high-risk injuries. It's better to do a fasciotomy that wasn't needed than to miss compartment syndrome.
Q: "What is the pathophysiology of compartment syndrome?"
Pathophysiology:
| Stage | Events |
|---|---|
| Initiating event | Haemorrhage, oedema from injury |
| Pressure rise | Within fixed compartment |
| Venous outflow obstruction | Capillary pressure exceeded |
| Further oedema | Capillary leak |
| Arterial inflow affected | When pressure exceeds diastolic |
| Ischemia | Muscle and nerve |
| Necrosis | If not decompressed |
The key concept is that tissue perfusion depends on the difference between arterial pressure and compartment pressure, not arterial pressure alone. This is why Delta P (Diastolic - Compartment pressure) is the key measurement.
Q: "What are the causes of compartment syndrome?"
Causes:
| Category | Examples |
|---|---|
| Fractures | Tibia, forearm, supracondylar (paediatric) |
| Soft tissue injury | Crush, contusion, burns |
| Vascular | Arterial injury with ischemia-reperfusion |
| Iatrogenic | Tight casts, extravasation, positioning |
| External compression | Prolonged pressure (coma, intoxication) |
| Increased volume | Bleeding disorders, snake bite |
Most common in orthopaedics: Tibial shaft fractures and paediatric supracondylar fractures.