What is the appropriate treatment and diagnostic approach for a patella fracture, including the use of computed tomography (CT) scans?

Diagnostic Approach and Treatment for Patella Fractures

Radiographs are the initial imaging modality of choice for suspected patella fractures, with CT scans reserved for cases where fracture patterns are complex or radiographically occult. 1

Initial Diagnostic Approach

Radiographic Evaluation

• Standard radiographs should include:
  • Anteroposterior (AP) view
  • Lateral view
  • Patellofemoral (sunrise/Merchant) view - particularly important for patellar fractures 1
  • Weight-bearing axial views may better assess patellofemoral kinematics 1

When to Consider Advanced Imaging

• CT Scan Indications:

  • Radiographically occult fractures with high clinical suspicion
  • Complex fracture patterns requiring better characterization
  • Preoperative planning for comminuted fractures
  • Assessment of articular surface involvement 1
  • When metal artifact reduction techniques are used, CT can effectively detect patellar complications 1

• MRI Indications:

  • Suspected concomitant soft tissue injuries (ligaments, tendons)
  • Osteochondral fractures
  • Sleeve fractures in pediatric patients 2
  • Superior for detecting bone marrow abnormalities 1

Classification and Treatment Algorithm

1. Non-displaced Fractures (< 2mm displacement)

• Treatment: Conservative management 3
  • Knee immobilization in extension
  • Protected weight-bearing
  • Early range of motion exercises when pain allows

2. Displaced Fractures (> 2mm displacement)

• Treatment: Surgical intervention 3
  • Open reduction and internal fixation (ORIF)
    • Tension band wiring technique shows good results with 83% excellent or good outcomes 4
    • Pre-patellar tension wiring with Kirschner wires for transverse fractures 4
  • Early mobilization post-fixation to prevent stiffness

3. Comminuted Fractures

• Treatment: Based on degree of comminution
  • Reconstructable: ORIF with multiple K-wires and tension band wiring 4
  • Severely comminuted: Partial patellectomy with repair of extensor mechanism
  • Total patellectomy in rare cases (satisfactory long-term results reported) 5

4. Polar Fractures

• Treatment: Based on fragment size and location
  • Small avulsion fragments: Excision and repair of extensor mechanism
  • Larger fragments: ORIF with tension band or suture fixation
  • Inferior pole sleeve fractures: Pull-out suture technique 2

5. Osteochondral Fractures

• Treatment: Based on size and location
  • Small, non-displaced: Conservative management
  • Displaced: ORIF with bioabsorbable pins or screws 6
  • MRI essential to exclude soft tissue injuries 6

Post-Treatment Protocol

1. Early Phase (0-4 weeks):

   • Immobilization in extension brace for 2-4 weeks
   • Protected weight-bearing as tolerated
   • Passive range of motion exercises starting 2 days post-operation 4

2. Intermediate Phase (4-8 weeks):

   • Progressive weight-bearing
   • Increased range of motion exercises
   • Begin quadriceps strengthening

3. Late Phase (8+ weeks):

   • Full weight-bearing
   • Full range of motion exercises
   • Return to activities based on fracture healing and quadriceps strength

Potential Complications to Monitor

• Infection (5% reported incidence) 4
• Hardware loosening (10% reported incidence) 4
• Malunion (4.5% reported incidence) 4
• Nonunion (4% reported incidence) 4
• Post-traumatic osteoarthritis (8.5% reported incidence) 4
• Patellofemoral pain and stiffness 3

Common Pitfalls to Avoid

• Inadequate radiographic views (missing the patellofemoral view)
• Overlooking occult fractures in patients with persistent pain
• Delayed surgical intervention for displaced fractures
• Insufficient fixation leading to early hardware failure
• Overly aggressive early mobilization in comminuted fractures
• Neglecting associated soft tissue injuries, especially in high-energy trauma
• Failing to recognize sleeve fractures in pediatric patients 2