Patella Fracture

Aka: Patella Fracture, Patellar Fracture

1. Epidemiology
   1. Rare in children
2. Mechanism
   1. Direct blow to anterior knee
3. Types
   1. Stellate Fracture
      1. Direct blow to Patella
   2. Sleeve Fracture
      1. Distal Patella Fracture due to quadriceps Muscle Contraction against a fixed lower leg
4. Signs
   1. Tenderness, swelling, Ecchymosis overlying the Patella
5. Imaging
   1. Knee XRay (esp. lateral Knee XRay and sunrise view)
6. Differential Diagnosis
   1. Bipartite Patella
      1. Consider Bilateal Knee XRay (expect both Patellas to be bipartite)
7. Management: Surgical versus non-surgical management
   1. Surgical indications
      1. Fracture step-off of >2 mm on articular surface
      2. Fracture separation of >3 mm
         1. Associated with Retinacular disruption and active knee extension loss
   2. Non-surgical Indications
      1. Non-displaced Patella Fracture with intact articular surface
      2. Active knee extension against gravity intact
      3. Minimal Patella Fracture fragment displacement
      4. Articular surface with minimal involvement
8. Management
   1. Acute management (for first week)
      1. Knee Immobilizer (knee in full extension)
      2. Non-weight bearing
      3. Ice and elevation
   2. Non-surgical management
      1. Week 1
         1. Start immobilization for 4-6 weeks
            1. Cylinder cast from groin to above ankle (with knee in full extension) OR
            2. Knee Immobilizer brace worn at all times except bathing (in highly compliant patients)
         2. Weight bearing
         3. Straight leg Exercises
      2. Week 2
         1. Repeat Knee XRay and confirm Fracture stable without displacement
         2. Continue knee immobilization
      3. Weeks 4-6
         1. Repeat Knee XRay and exam
         2. Continue knee immobilization until XRay demonstrates radiographic union
      4. Weeks 6-10
         1. Physical therapy for knee range of motion and quadriceps strengthening
         2. Repeat exam every 3-4 weeks until fully healed (typically 8-10 weeks from start of immobilization)
9. Complications
   1. Inability to extend knee
      1. Disrupted knee extension mechanism (Patellar tendon)
   2. Premature Knee Osteoarthritis
      1. Related to articular surface defects
10. References
    1. Eiff (1998) Fracture Management for Primary Care, W.B. Saunders, p. 179-83
    2. Spangler and Tollefson (2014) in Herbert 14(6): 9-11