What is the management for a non-displaced patellar fracture?

Management of Non-Displaced Patellar Fractures

Non-displaced patellar fractures with an intact extensor mechanism should be treated conservatively with immobilization in a knee immobilizer or cast for 4-6 weeks, followed by progressive rehabilitation. 1

Initial Assessment and Diagnosis

• Evaluate for:

  • Integrity of the extensor mechanism (ability to perform straight leg raise)
  • Displacement of fracture fragments (>2-3mm step-off or >1-4mm displacement requires surgery)
  • Articular surface disruption
  • Associated soft tissue injuries

• Radiographic evaluation:

  • Standard anteroposterior and lateral views of the knee
  • Consider CT scan for complex fracture patterns to better understand fracture complexity

Conservative Management Protocol

Immobilization Phase (0-4 weeks)

• Immobilize the knee in full extension using:

  • Knee immobilizer or cylindrical cast
  • Ensure the knee is maintained in full extension to protect the extensor mechanism

• Pain management:

  • NSAIDs if not contraindicated
  • Short-term opioids only if necessary for severe pain
  • Ice and elevation to reduce swelling

Early Rehabilitation Phase (4-6 weeks)

• Transition from immobilization to controlled motion at approximately 4 weeks 2
• Begin with:
  • Gentle passive range of motion exercises
  • Pendulum exercises
  • Progress to active-assisted range of motion as tolerated

Progressive Rehabilitation Phase (6-12 weeks)

• Advance to active range of motion exercises
• Begin strengthening exercises for quadriceps and hamstrings
• Restrict above chest level activities until fracture healing is evident
• Avoid overly aggressive physical therapy that may increase risk of displacement 2

Follow-up Protocol

• Clinical and radiographic follow-up at 2-week intervals initially to assess:
  • Pain levels
  • Range of motion progress
  • Fracture healing
  • Functional improvement 2

Indications for Surgical Management

Conservative management is only appropriate when ALL of the following criteria are met:

• Fracture is non-displaced (<2-3mm step-off and <1-4mm displacement)
• Extensor mechanism is intact
• No significant articular surface disruption

Surgical fixation is indicated when any of these criteria are not met 1, 3

Prevention of Future Fractures

• Calcium (1000-1200 mg/day) and vitamin D (800 IU/day) supplementation 2
• Fall prevention strategies
• Consider bone health assessment and referral if appropriate
• Consider enrollment in a Fracture Liaison Service for systematic evaluation of subsequent fracture risk 4

Common Pitfalls and Caveats

1. Missed Extensor Mechanism Disruption: Always test active straight leg raise to ensure the extensor mechanism is intact before deciding on conservative management.

2. Inadequate Immobilization: Failure to maintain full extension during the immobilization period can lead to extensor lag and functional limitations.

3. Premature Mobilization: Starting range of motion exercises too early may lead to displacement of the fracture.

4. Overlooking Comminution: What appears as a simple non-displaced fracture on plain radiographs may be more complex; consider CT imaging in uncertain cases.

5. Hardware-Related Complications: If surgical management becomes necessary, be aware that symptomatic hardware is a frequent complication that may require removal after fracture healing 1.

6. Rehabilitation Progression: Avoid overly aggressive physical therapy, as this may increase the risk of displacement and poor outcomes 2.