Durability: Wear Performance
As today’s patients seek more active lifestyles, knee implants will be expected to endure more stress without succumbing to wear. However, the functional lifetime demand of younger and active patients is 10-fold greater than the estimated functional lifetime of traditional implant bearings1. VERILAST◊ Technology from Smith & Nephew is the only bearing technology with published results of 45 Million Cycles of knee in-vitro wear simulation testing with the LEGION Primary Knee System. This means the replacement may provide improved wear performance. More importantly, if implanted earlier, it may restore patients to their active lifestyles.
The implants identified below were tested by their manufacturers using different testing protocols and, therefore, the results are not directly comparable.

Mean volumetric wear rates of CoCr against conventional polyethylene (CPE), CoCr against crosslinked polyethylene (XLPE) and OXINIUM◊ against XLPE as published by the respective companies with their respective implants. Please see References 1-7 for testing information.
Durability: Metal Sensitivity
Just as metal ions are a well described problem for many hip replacement patients, cobalt, chromium and nickel are commonly cited allergens for knee replacement patients. In several cases, sensitivity to one or more of the allergens has resulted in revisions for these patients9-12.
Surgeons should be aware that all metal implants contain varying amounts of cobalt, chromium, and nickel. When selecting the appropriate implant, surgeons should consider the composition of each implant before use. To help with this decision, VERILAST Technology incorporates proprietary OXINIUM alloy. Compared to cobalt chrome, OXINIUM alloy has much less cobalt (<0.002%), chromium (<0.02%) and nickel (<0.0035%) content.
Metal content of implants13



Clinical studies14

References
1. R. Papannagari, G. Hines, J. Sprague and M. Morrison, “Long-term wear performance of an advanced bearing knee technology,” ISTA, Dubai, UAE, Oct 6-9, 2010.
2. H. M. J. McEwen, P. I. Barnett, C. J. Bell, R. Farrar, D. D. Auger, M. H. Stone and J. Fisher, The influence of design, materials and kinematics on the in vitro wear of total knee replacements, J. Biomech, 2005;38(2):357-365.
3. A. Parikh, M. Morrison and S. Jani, Wear testing of crosslinked and conventional UHMWPE against smooth and roughened femoral components, Orthop Res Soc, San Diego, CA, Feb 11-14, 2007, 0021.
4. AA. Essner, L. Herrera, S. S. Yau, A. Wang, J. H. Dumbleton and M. T. Manley, Sequentially crosslinked and annealed UHMWPE knee wear debris, Orthop Res Soc, Washington D.C., 2005, 71.
5. L. Herrera, J. Sweetgall, A. Essner and A. Wang, “Evaluation of sequentially crosslinked and annealed wear debris, World Biomater Cong, Amsterdam, May 28-Jun 1, 2008, 583.
6. C. Schaerer, K. Mimnaugh, O. Popoola and J. Seebeck, “Wear of UHMWPE tibial inserts under simulated obese patient conditions,” Orthop Res Soc, New Orleans, LA, Feb 6-10, 2010, 2329.
7. Biomet publication, Claims for E1 Antioxidant Infused Technology
8. Ref: DePuy Attune 510 K Document K101433 Dec 10, 2010
9. Hallab NJ, Anderson S, Stafford T, Glant T, Jacobs JJ. “Lymphocyte responses in patients with total hip arthroplasty.” J Orthop Res 2005; 232:384e91.
10. Niki, Yasuo et al. “Screening for symptomatic metal sensitivity: a prospective study of 92 patients undergoing total knee arthroplasty.” Biomaterials 26 (2005) 1019–1026.
11. Nasser, S. “Biology of foreign bodies: tolerance, osteolysis, and allergy”, Total Knee Arthroplasty, J. Bellemans, M.D. Ries, and J. Victor (eds.), Springer Verlag, Heidelberg, Germany, 2005, pp. 343-352.
12. Granchi, Donatella et al. “Sensitivity to implant materials in patients with total knee arthroplasties.” Biomaterials 29 (2008) 1494-1500.
13. ASTM International Standard Specification for Wrought Zirconium-2.5Niobium Alloy for Surgical Implant Applications (UNS R60901) Designation: F 2384 – 05 and Standard Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings and Casting Alloy for Surgical Implants (UNS R30075): Designation: F 75 – 07.
14. Hallab, Nadim et al. Metal Sensitivity in Patients with Orthopaedic Implants, The Journal of Bone & Joint Surgery, Vol 83-A No. 3. March 2001 p428-43616.
15. Total knee arthroplasty at 15-17 years: does implant design affect outcome? Victor J, Ghijselings S, Tajdar F, Van Damme G, Deprez P, Arnout N, Van Der Straeten C., Int Orthop. 2014 Feb;38(2):235-41. doi: 10.1007/s00264-013-2231-8. Epub 2013 Dec 18.
16. Bhandari, Saccone, Sprague, “The GENESIS II Total Knee System in Primary Total Knee Arthroplasty: A Systematic Literature Review of Clinical Outcomes”, Bone&Joint Outcome, Vol 01, No 01-August 2011.
17. Smith & Nephew Technical Memo TM-11-013A Comparison of LEGION and GENESIS II OXINIUM Femoral Designs.
18. LEGION Primary Knee System: A Prospective, Multi-Center, Non-Randomized, Safety and Efficacy Clinical Study of the LEGION Primary Knee System for Primary Total Knee Replacement in Subjects with Degenerative Knee Disease. 10-K300-95301, 29 April 2014. Version 1.0.
19. Australian Orthopaedic Association National Joint Replacement Registry. Annual Report. Adelaide:AOA; 2014 Table KT10: Cumulative Percent Revision of Primary Total Knee Replacement with Cement Fixation.
20. Australian Orthopaedic Association National Joint Replacement Registry. Annual Report. Adelaide:AOA; 2014 Table KT11: Cumulative Percent Revision of Primary Total Knee Replacement (Primary Diagnosis OA).