Knee Replacement Implant Brand Selection
No specific implant brand (Zimmer, Smith & Nephew, or Stryker) demonstrates superior clinical outcomes, and the choice should be based on surgeon familiarity and institutional cost considerations rather than brand preference. 1, 2
Evidence on Brand Comparison
The most direct evidence comparing these specific brands comes from a large prospective cohort study of 4,135 patients that evaluated five major implant brands including Zimmer NexGen, Smith & Nephew Genesis II, and others. This study found no clinically significant differences in functional outcomes (KOOS scores) between any implant brands at two years postoperatively. 3 All groups showed greater than 80% patient satisfaction across all domains, though minor statistical differences in satisfaction rates existed (Zimmer NexGen patients showed slightly higher satisfaction odds ratio 1.63, p=0.006). 3
What Actually Matters: Design Features, Not Brand
The American Academy of Orthopaedic Surgeons provides strong evidence that major implant design variations produce equivalent outcomes—meaning the fundamental design choices matter far more than the manufacturer's logo. 1, 2
Design Elements with Equivalent Outcomes:
Fixation method: Cemented versus uncemented components show no clinically meaningful difference in outcomes, complications, or revision rates 1
Tibial component type: All-polyethylene versus modular tibial components produce equivalent pain, function, and revision rates 1, 2
Cruciate design: Posterior-stabilized versus cruciate-retaining designs show no difference in outcomes or complications 1, 2
Patellar resurfacing: Pain and functional outcomes are equivalent whether the patella is resurfaced or not, though resurfacing may reduce revision surgery beyond 5 years 2
Technologies NOT Worth Premium Pricing
Strong evidence demonstrates that expensive technological additions provide no clinical benefit: 1, 2
Surgical navigation: No difference in outcomes or complications versus conventional instrumentation 4, 1, 2
Patient-specific instrumentation (PSI): No benefit in pain, function, or alignment over conventional techniques 1, 2
Robotic assistance: Increases operative time without improving long-term clinical outcomes or survivorship 2
The Patient-Specific Implant Exception
One area where customization shows promise: truly patient-specific implants (not just patient-specific instruments) demonstrate higher patient-reported outcomes in direct comparison studies. Patients who received customized implants in one knee and off-the-shelf implants in the contralateral knee reported significantly higher KOOS scores (82 vs 77, p=0.03) and Forgotten Joint Scores (68 vs 58, p=0.04), with 72.3% preferring their customized knee. 5 However, these remain investigational and not widely available from the major manufacturers you're asking about. 6
Clinical Bottom Line
Select implants based on: 3
- Surgeon experience and familiarity with the specific system—this likely matters more than brand
- Institutional cost negotiations—since outcomes are equivalent, price differences may not be justified
- Proven long-term survivorship data—conventional designs from all three manufacturers (Zimmer, Smith & Nephew, Stryker) have demonstrated 89% good or excellent outcomes up to 5 years 7
Critical Caveat
A 1997 review found that 54% of total knee replacements on the market had no published results in peer-reviewed journals, and frequent design modifications make long-term outcome tracking difficult. 8 Avoid newly introduced or recently modified designs without published survivorship data, regardless of manufacturer. 8
The evidence strongly suggests that healthcare administrators and surgeons should negotiate contracts based on cost rather than presumed superiority of one brand over another, as clinical outcomes remain equivalent across major manufacturers when fundamental design principles are sound. 3