What is the initial approach to managing a knee injury in the emergency department (ED)?

Initial Approach to Knee Injury in the Emergency Department

The optimal initial approach to knee injury in the emergency department should include radiographs for patients meeting Ottawa rule criteria, followed by appropriate immobilization and RICE therapy (rest, ice, compression, elevation) for most soft tissue injuries. 1

Initial Assessment and Imaging

When to Order Radiographs

Radiographs should be the initial imaging modality for knee injuries when any of these Ottawa rule criteria are present:

• Focal tenderness of the knee
• Inability to bear weight (four steps) immediately and in the ED
• Knee effusion 1

Additionally, radiographs should be obtained regardless of Ottawa criteria in patients with:

• Gross deformity
• Palpable mass
• Penetrating injury
• Prosthetic hardware
• Unreliable history/exam due to multiple injuries
• Altered mental status
• Neuropathy
• History suggesting high fracture risk 1

Standard Radiographic Views

• Minimum of two views: anteroposterior (AP) and lateral
• Lateral view should be obtained with knee at 25-30 degrees flexion
• Consider cross-table lateral view to visualize lipohemarthrosis (indicates intra-articular fracture)
• Additional views for specific concerns:
  • Patellofemoral view for suspected patellar fractures/subluxation/dislocation 1

Management Based on Injury Type

Soft Tissue Injuries (Ligament/Meniscal)

1. Initial treatment (first 24-72 hours):

   • Rest
   • Ice application (10+ minutes)
   • Compression
   • Elevation
   • Anti-inflammatory medication 2, 3

2. Specific ligament injuries:

   • MCL tears: Most can be managed non-operatively 4
   • Grade I-II ACL tears: May be managed non-operatively initially
   • Grade III ACL tears: Often require surgical intervention, especially in athletes 4

3. Meniscal injuries:

   • Recent evidence shows acute traumatic meniscus tears in patients under 40 can be successfully treated non-operatively 4

Patellar Dislocation

• Short period of knee bracing in extension
• Progressive weight bearing as tolerated 4

Significant Trauma/Knee Dislocation

• Immediate vascular assessment (30% risk of vascular injury with posterior knee dislocation)
• Consider CTA for suspected vascular injuries (less invasive than conventional angiography with similar accuracy) 1
• Immobilize and urgent orthopedic consultation

Special Considerations

Burns

• Cool thermal burns with cool or cold water for at least 10 minutes
• Monitor for hypothermia when cooling large burns
• Loosely cover with sterile, dry dressing 1

Musculoskeletal Trauma

• Do not move or straighten injured extremity
• Splint to limit pain and prevent further injury
• If extremity is blue or extremely pale, activate EMS immediately 1

Pitfalls to Avoid

1. Missing vascular injuries:

   • Always assess distal pulses in significant knee trauma
   • Knee dislocations require urgent vascular evaluation even if spontaneously reduced

2. Inappropriate imaging:

   • MRI is not indicated as initial imaging for acute knee trauma
   • CT is not routinely used as initial imaging but may be helpful for suspected occult fractures 1

3. Inadequate pain management:

   • Paracetamol (acetaminophen) is recommended as first-line oral analgesic for pain
   • NSAIDs should be considered in patients unresponsive to paracetamol 1

4. Delayed follow-up:

   • Ensure appropriate orthopedic follow-up for significant injuries
   • Athletic patients should be offered surgical reconstruction options when appropriate 2