What is the best implant for knee replacement?

Best Implant for Total Knee Arthroplasty

For primary total knee arthroplasty, use either cemented or uncemented tibial and femoral components with conventional ultra-high molecular weight polyethylene (UHMWPE) bearing surfaces, as there is no clinically meaningful difference in outcomes, complications, or revision rates between fixation methods or between conventional and highly cross-linked polyethylene. 1

Component Fixation: Cemented vs. Uncemented

Strong evidence supports equivalent outcomes between cemented and uncemented fixation methods:

• Tibial component fixation: Either cemented or uncemented tibial components achieve similar functional outcomes, complication rates, and revision surgery rates 1
• Femoral and tibial components together: Moderate evidence shows no difference in complications or revision rates when comparing all-cemented versus all-uncemented femoral and tibial components 1
• Hybrid fixation: Strong evidence supports using either all-polyethylene or modular tibial components, as outcomes are equivalent 1

The choice between fixation methods can be based on surgeon preference, patient bone quality, and cost considerations, as clinical outcomes are comparable across all approaches.

Bearing Surface Material: Conventional vs. Highly Cross-Linked Polyethylene

Conventional UHMWPE remains the gold standard bearing surface, with no proven clinical advantage for highly cross-linked polyethylene (HXLPE) in knee arthroplasty:

• Conventional UHMWPE has been the predominant bearing surface since 1962, offering enhanced wear resistance and reduced friction compared to other polymers 1
• Large registry data (77,084 TKAs) shows no difference in all-cause revision risk (HR 1.05, p=0.620), aseptic revision (HR 1.01, p=0.954), or septic revision (HR 1.11, p=0.519) between HXLPE and conventional polyethylene at 5-year follow-up 2
• Cross-linked polyethylene shows only minimal effect, if any, on knee arthroplasty survival rates 3
• While one multicenter study showed slightly better functional scores with HXLPE at 4-5 years, there were no osteolysis or polyethylene failures in either group 4

Key consideration: HXLPE increases cost without proven long-term benefit beyond 10 years, making conventional UHMWPE the more cost-effective choice 2

All-Polyethylene vs. Modular Tibial Components

Both all-polyethylene and modular metal-backed tibial components are appropriate options:

• Strong evidence supports equivalent outcomes between all-polyethylene and modular tibial components 1
• All-polyethylene components offer advantages: lower cost, elimination of backside wear, no liner dislocation risk, and excellent long-term survival (98.5% at 12.8 years) 5
• Long-term results with all-polyethylene tibial components show average Knee Society Score of 82.6 points with only 1.5% revision rate for infection and minimal aseptic loosening 5

Common pitfall: All-polyethylene components are often restricted to elderly, low-activity patients, but current evidence supports broader indications given excellent long-term outcomes 5

Cruciate-Retaining vs. Posterior-Stabilized Design

Either posterior-stabilized or posterior cruciate-retaining designs are appropriate:

• Strong evidence shows no difference in outcomes or complications between posterior-stabilized and posterior cruciate-retaining arthroplasty designs 1
• Design selection should be based on intraoperative ligament integrity and surgeon experience rather than expected outcome differences

Technologies NOT Recommended

Avoid these technologies as they provide no clinical benefit:

• Surgical navigation: Strong evidence shows no difference in outcomes or complications 1, 6
• Patient-specific instrumentation (PSI): Strong evidence shows no difference in pain or functional outcomes compared to conventional instrumentation 1
• Robotic assistance: The American Academy of Orthopaedic Surgeons provides strong evidence against intraoperative navigation, with conventional TKA achieving 89% good or excellent outcomes 6

Material Composition Summary

For the metal components:

• Titanium alloy (Ti-6Al-4V) remains the preferred metal for major orthopedic components due to biocompatibility and bio-integration 1
• Novel beta-titanium alloys (Ti-Nb-Zr-Ta) show promise with lower elastic modulus and reduced stress shielding, but are not yet standard of care 1

For the bearing surface:

• Conventional UHMWPE is the gold standard, with minimum fossa thickness of 4mm recommended 1
• High-grade cross-linked UHMWPE offers no proven clinical advantage despite theoretical wear reduction benefits 3, 2