A 35-year-old male sustains a fracture of his forearm and undergoes immobilization with a plaster of Paris (POP) cast. A few hours later, he complains of severe pain in the affected limb, which worsens with passive movement of his fingers. The cast feels excessively tight, and there is swelling in the limb. What is the most important complication of plaster of Paris application?
A. Compartment syndrome
B. Joint stiffness
C. Joint immobility
D. Volkman ischemic contracture
Correct Answer: A. Compartment syndrome
Explanation:
Compartment syndrome is the most important and potentially life-threatening complication of plaster of Paris (POP) cast application. It occurs when the pressure within a closed compartment (bound by fascia or a cast) rises to levels that impair blood flow, leading to ischemia and potential tissue necrosis.
Key Features of Compartment Syndrome:
- Mechanism:
- Increased compartmental pressure can be due to:
- Tight casts or bandages.
- Swelling from trauma or fractures under the cast.
- When pressure exceeds the capillary perfusion pressure, it leads to reduced blood flow, tissue ischemia, and nerve compression.
- Increased compartmental pressure can be due to:
- Clinical Features (6 Ps):
- Pain: Severe and disproportionate to the injury, worsened by passive movement.
- Paresthesia: Tingling or numbness due to nerve compression.
- Pallor: Affected limb may appear pale due to reduced blood flow.
- Pulselessness: A late and ominous sign, indicating arterial compromise.
- Paralysis: Weakness or inability to move the limb.
- Poikilothermia: The limb feels cool to touch.
- Risk Factors:
- Tight casts or bandages.
- High-energy fractures (e.g., tibia, forearm).
- Prolonged immobilization or delayed fracture reduction.
- Complications of Untreated Compartment Syndrome:
- Volkman ischemic contracture: A late and irreversible consequence caused by prolonged ischemia, resulting in fibrosis of muscles and permanent deformity.
- Nerve damage and muscle necrosis.
Why It’s the Most Important Complication:
- Acute compartment syndrome is a surgical emergency that requires prompt recognition and intervention to prevent irreversible damage.
- If unaddressed, it can lead to permanent disability, amputation, or even death due to systemic complications like rhabdomyolysis and acute kidney injury.
Analysis of Other Options:
B. Joint stiffness:
- Common but non-emergent complication. Results from prolonged immobilization and lack of movement during cast use. Managed with physiotherapy post-cast removal.
C. Joint immobility:
- Similar to joint stiffness, immobility occurs with prolonged immobilization. Not life-threatening and typically reversible with rehabilitation.
D. Volkman ischemic contracture:
- A late sequela of untreated compartment syndrome. It results in permanent deformity and loss of function but is preventable if compartment syndrome is managed promptly.
Diagnosis of Compartment Syndrome:
- Clinical Diagnosis:
- Severe, unrelenting pain and tense swelling are key indicators.
- Pain with passive stretching of muscles within the compartment.
- Pressure Measurement:
- Intracompartmental pressure >30 mmHg or within 30 mmHg of diastolic pressure confirms the diagnosis.
Management:
- Emergency Measures:
- Remove the cast immediately if compartment syndrome is suspected.
- Elevate the limb to the level of the heart (not above, as it may worsen ischemia).
- Definitive Treatment:
- Fasciotomy: Surgical decompression of the affected compartment to relieve pressure and restore perfusion.
- Postoperative Care:
- Wound care and monitoring for complications like infection or delayed closure.
- Physical therapy to regain function.
Summary:
Compartment syndrome is the most critical complication of plaster of Paris (POP) cast application, characterized by severe pain, swelling, and impaired circulation in the affected limb. It occurs when excessive pressure within a closed compartment leads to tissue ischemia and nerve compression. Early recognition of symptoms, such as pain disproportionate to the injury and tight casts, is essential to prevent irreversible damage, including Volkman ischemic contracture. Prompt treatment involves cast removal and, if necessary, fasciotomy to relieve pressure. Proper cast application techniques and regular monitoring can prevent this life-threatening condition.