Principles of Revision Total Knee Arthroplasty
Revision total knee arthroplasty (TKA) is a technically demanding procedure that requires thorough preoperative planning, adherence to specific surgical principles, availability of diverse implant options, and adequate bone graft to achieve successful outcomes.
Key Principles of Revision TKA
1. Understanding the Cause of Failure
- Identify the specific reason for primary TKA failure before planning revision surgery
- Most common causes of failure requiring revision 1:
- Aseptic loosening (39.9%)
- Infection (27.4%)
- Instability (7.5%)
- Periprosthetic fracture (4.7%)
- Arthrofibrosis (4.5%)
2. Preoperative Assessment and Planning
- Radiographic evaluation is essential:
- Standing AP and lateral views
- Tangential axial view of patellofemoral joint
- Hip-to-ankle radiographs for assessment of alignment 1
- Infection must be excluded in all cases of pain persisting >6 months after joint replacement 1
- Laboratory testing for markers of infection
- Preoperative planning for bone loss management and implant selection
3. Surgical Exposure
- Adequate surgical exposure is critical for successful revision
- May require specialized approaches to deal with scarring from previous surgery
- Preservation of soft tissue attachments where possible
4. Restoration of Limb Alignment
- Correction of mechanical axis is fundamental
- Use of hip-to-ankle radiographs for optimal assessment of alignment 1
- Aim for neutral alignment to improve implant longevity
5. Soft Tissue Balance
- Achieving appropriate soft tissue balance is more challenging in revision cases
- May require specialized implant designs to address instability
- Balance in both flexion and extension is critical
6. Implant Selection and Positioning
- Revision implant systems are generally required rather than primary components 2
- Key technical principles 2:
- Tibial platform establishment first
- Femoral component rotation and sizing to stabilize knee in flexion
- Evaluation of patellar height as indicator of joint line position
- Stabilization of knee in extension
7. Bone Defect Management
- Identification and classification of bone defects
- Options include:
- Cement augmentation
- Metal augments
- Bone grafting
- Porous metals as "modular fixation interfaces" 2
8. Joint Line Restoration
- Recognition that joint line is a three-dimensional concept, not simply a line 2
- Restoration of appropriate joint line is critical for patellofemoral mechanics and overall function
9. Component Fixation
- Stem extensions improve fixation and may guide component positioning 2
- Strong evidence supports either cemented or cementless fixation options based on similar functional outcomes and complication rates 1
10. Postoperative Management
- Early mobilization and physical therapy are crucial for optimal outcomes 1
- Strong evidence supports not using continuous passive motion machines 1
Challenges and Outcomes
Revision TKA outcomes are generally inferior to primary TKA 3, 4:
- Higher failure rates
- Increased risk of complications
- More complex recovery
The most common causes of revision TKA failure include 5:
- Infection (38.5% of failures)
- Aseptic loosening (20.9%)
- Instability (14.2%)
Risk factors for revision TKA failure 5:
- Septic index revision (OR 1.91)
- Male gender (OR 1.41)
- Age less than 65 (OR 1.56)
Critical Considerations
- Revision TKA is not a repeat primary arthroplasty but a distinct procedure with its own principles 3
- In cases of unexplained pain, reoperation is unwise and frequently associated with suboptimal results 1
- Complete revision is generally recommended in most cases rather than partial component revision 2
By following these principles, surgeons can maximize the chances of successful outcomes in revision TKA, though patients should be counseled that results are typically not as good as primary TKA.