Can patients with a patella fracture after total knee replacement (TKR) who are placed in a hinged knee brace weight-bear as tolerated?

Management of Patella Fracture After Total Knee Replacement

Patients with patella fractures after total knee replacement who are placed in a hinged knee brace can weight-bear as tolerated, provided the extensor mechanism is intact and the patellar implant is stable.

Classification and Assessment of Patella Fractures After TKR

Patella fractures after total knee arthroplasty occur in approximately 0.68-3.8% of cases 1, 2. Treatment decisions should be based on three critical factors:

1. Integrity of the extensor mechanism
2. Fixation status of the patellar implant
3. Quality of the remaining bone stock

These fractures can be classified into three types:

• Type I: Stable implant with intact extensor mechanism
• Type II: Disruption of the extensor mechanism
  • Type IIA: Disruption <1 cm
  • Type IIB: Disruption ≥1 cm
• Type III: Loose patellar component with intact extensor mechanism

Weight-Bearing Recommendations

For Type I Fractures (Stable Implant, Intact Extensor Mechanism):

• Weight-bearing as tolerated is appropriate when using a hinged knee brace
• These fractures can be successfully managed non-operatively with minimal complications 1
• The hinged brace provides stability while allowing controlled motion

For Type II Fractures (Disrupted Extensor Mechanism):

• Weight-bearing should be restricted
• These fractures typically require surgical intervention
• High complication rate (6 out of 11 cases) and reoperation rate (5 out of 11 cases) have been reported 1

For Type III Fractures (Loose Patellar Component):

• Weight-bearing should be restricted
• Surgical intervention is typically required
• High complication rate (9 out of 20 cases) and reoperation rate (4 out of 20 cases) have been reported 1

Imaging Assessment

Proper imaging is essential for accurate classification and treatment planning:

• Radiographs: Initial examination should include AP, lateral, and axial views that demonstrate the entire prosthesis and surrounding bone 3
• CT scan: May be needed for radiographically occult fractures using metal artifact reduction techniques 3
• Weight-bearing axial radiographs: Can better assess patellofemoral kinematics 3

Treatment Algorithm

1. Assess fracture type through clinical examination and imaging

2. For Type I fractures:

   • Immobilize in a hinged knee brace
   • Allow weight-bearing as tolerated with proper gait pattern
   • Monitor for pain, effusion, or increased temperature
   • Follow with serial radiographs to ensure healing

3. For Type II and III fractures:

   • Surgical consultation is required
   • Weight-bearing restrictions should be implemented
   • Be aware of high complication rates with surgical intervention 2

Rehabilitation Considerations

For Type I fractures with hinged knee brace:

• Begin isometric quadriceps exercises when pain allows 3
• Progress to concentric closed-chain exercises when quadriceps is reactivated
• Add neuromuscular training to strength training for optimal outcomes 3
• Monitor quality of movement as a measure of neuromuscular recovery 3

Common Pitfalls and Caveats

• Attempting operative treatment for minimally displaced fractures with stable implants can lead to unnecessary complications 2
• Failing to identify disruption of the extensor mechanism can lead to inappropriate weight-bearing recommendations
• Four of nine patients treated with excision of an extruded patella button developed deep infection 2
• Both patients treated with open reduction internal fixation (ORIF) developed nonunion 2

Remember that the primary goal is to maintain function while avoiding complications. For most Type I fractures, non-operative management with a hinged knee brace and weight-bearing as tolerated provides good outcomes with minimal complications.