What is the best knee replacement implant design?

Knee Replacement Implant Design Selection

Direct Answer Based on Strongest Evidence

The American Academy of Orthopaedic Surgeons provides strong evidence that there is no clinically meaningful difference between major implant design variations in total knee arthroplasty—cemented versus uncemented fixation, all-polyethylene versus modular tibial components, and posterior-stabilized versus cruciate-retaining designs all produce equivalent outcomes, complications, and revision rates. 1, 2

Component Fixation: Cemented vs. Uncemented

Both cemented and uncemented fixation methods are equally acceptable for femoral and tibial components, as they demonstrate no difference in functional outcomes, complication rates, or revision surgery rates. 1, 2

• Strong evidence supports using either cemented or uncemented tibial component fixation with similar long-term survivorship 1
• Moderate evidence confirms equivalent outcomes when comparing all-cemented versus all-uncemented femoral and tibial components 1, 2
• The choice between fixation methods should be based on surgeon experience and bone quality rather than superiority of one technique over another 2

Tibial Component Design: All-Polyethylene vs. Modular

Strong evidence supports equivalent outcomes between all-polyethylene and modular tibial components—either option is acceptable. 1, 2

• No difference exists in pain, function, or revision rates between these two tibial component designs 1
• The decision can be made based on surgical preference and specific patient anatomy 2

Bearing Surface Material

Conventional ultra-high molecular weight polyethylene (UHMWPE) remains the gold standard bearing surface with no demonstrated clinical benefit from highly cross-linked polyethylene. 2

• Conventional UHMWPE has been the predominant bearing surface since 1962, offering enhanced wear resistance and reduced friction 2
• Strong evidence shows no clinically meaningful difference between conventional and highly cross-linked polyethylene in outcomes or complications 2

Cruciate-Retaining vs. Posterior-Stabilized Design

Strong evidence demonstrates no difference in outcomes or complications between posterior-stabilized and posterior cruciate-retaining designs. 2

• Both designs achieve equivalent pain relief, functional improvement, and complication rates 2
• The choice should be based on ligament integrity at surgery and surgeon familiarity with the technique 2

Patellar Resurfacing Considerations

Strong evidence supports no difference in pain or function with or without patellar resurfacing, though moderate evidence suggests resurfacing may decrease cumulative revision surgeries after 5 years. 1

• Pain and functional outcomes are equivalent whether the patella is resurfaced or not 1
• Patellar resurfacing may reduce the need for revision surgery beyond 5 years postoperatively 1

Technologies NOT Recommended

The American Academy of Orthopaedic Surgeons provides strong evidence against using surgical navigation, patient-specific instrumentation (PSI), and robotic assistance as they provide no clinical benefit while increasing costs and operative time. 1, 2, 3

• Strong evidence shows no difference in outcomes or complications with intraoperative navigation compared to conventional instrumentation 1, 3
• Patient-specific instrumentation provides no benefit in pain, function, or alignment over conventional techniques 1, 2
• Robotic systems increase operative time without improving long-term clinical outcomes or survivorship 3

Material Composition

Titanium alloy (Ti-6Al-4V) remains the preferred metal for major orthopedic components due to superior biocompatibility and bio-integration properties. 2

Common Pitfalls to Avoid

• Avoid using tibial stems in primary TKA when bone is healthy with good structural properties—stems are reserved for revision cases or significant bone defects 4
• Do not pursue expensive technologies (navigation, robotics, PSI) expecting improved outcomes—conventional instrumentation achieves 89% good or excellent outcomes for pain and function up to 5 years 3
• Avoid metal-backed patellar components, which have higher revision rates compared to all-polyethylene designs 1

Risk Factor Considerations That Impact Outcomes

Strong evidence supports that obese patients have less improvement in outcomes with TKA, requiring preoperative counseling about realistic expectations. 1

• Moderate evidence shows patients with diabetes are at higher risk for complications 1
• Moderate evidence indicates patients with chronic pain conditions have less improvement in patient-reported outcomes 1
• Limited evidence suggests patients with depression/anxiety symptoms experience less improvement in outcomes 1