Implant Selection for Total Knee Replacement
For TKR implant selection, choose based on surgeon familiarity and patient factors rather than specific implant design, as strong evidence shows no difference in outcomes between posterior-stabilized versus posterior cruciate-retaining designs, all-polyethylene versus modular tibial components, or cemented versus uncemented fixation. 1
Key Implant Design Considerations
Cruciate-Substitution Design
- Either posterior-stabilized (PS) or posterior cruciate-retaining (PCR) designs are acceptable - strong evidence demonstrates no difference in outcomes or complications between these approaches 1
- Select based on your surgical experience and the patient's ligamentous integrity
Tibial Component Selection
- Use either all-polyethylene or modular tibial components - strong evidence shows no difference in outcomes 1
- Both options provide equivalent functional results and complication rates
Fixation Method
The AAOS guidelines provide clear flexibility here:
Cemented vs. Uncemented:
- Either cemented or uncemented tibial fixation is appropriate - strong evidence shows similar functional outcomes, complication rates, and revision rates 1
- Either all-cemented or all-uncemented components work equally well - moderate evidence supports similar complication and revision rates 1
- Hybrid fixation (uncemented femoral, cemented tibial) is also acceptable - moderate to limited evidence shows comparable outcomes 1
Patellar Resurfacing
- Consider patellar resurfacing to potentially improve outcomes - while strong evidence shows no difference in pain or function with or without resurfacing, moderate evidence suggests resurfacing may improve outcomes 1
- This represents a nuanced recommendation where the evidence is mixed but leans toward resurfacing
What NOT to Use
Avoid these technologies for routine TKR:
- Do not use intraoperative navigation - strong evidence shows no differences in outcomes or complications versus conventional instrumentation 1
- Do not use patient-specific instrumentation (PSI) - strong to moderate evidence shows no benefit in outcomes, complications, or transfusion rates 1
These additive technologies increase cost and operative time without improving patient outcomes.
Specific Implant Systems
Recent research demonstrates excellent outcomes with several contemporary systems:
- Persona Knee System (Zimmer Biomet): 95.7% survival at 11 years with mean FJS-12 of 69.52 and OKS of 38.63 2
- Physica KR (kinematic-retaining): 99.4% survivorship at 5 years with exceptional patient-reported outcomes 3
- Triathlon (Stryker): Valid alternative to discontinued PFC system with comparable outcomes and only one revision at 10 years 4
- Porous tantalum cementless: 95.7% survival at 7 years with no aseptic loosening 5
Critical Surgical Considerations
Tourniquet Use:
- Avoid routine tourniquet use - while it decreases intraoperative blood loss (moderate evidence), it increases short-term postoperative pain (strong evidence) and may increase risk of implant loosening after 5 years (HR 1.56) 1, 6
- Recent Swedish registry data of 149,616 TKRs shows increased revision for loosening beyond 5 years with tourniquet use 6
Clinical Algorithm for Implant Selection
- Start with your most familiar implant system - surgeon experience matters more than specific design features
- Choose fixation based on bone quality:
- Good bone stock: either cemented or uncemented acceptable
- Poor bone quality: consider cemented for immediate stability
- Select PS vs PCR based on:
- PCL integrity (if deficient, use PS)
- Your surgical comfort level
- Consider patellar resurfacing in most cases given potential benefit
- Use conventional instrumentation - skip navigation and PSI
- Avoid routine tourniquet to reduce pain and potential late loosening risk
The evidence strongly supports that no single implant design has superior outcomes - focus on proper surgical technique, component alignment, and soft tissue balancing rather than chasing specific implant features 1.