The Evolution® medial-pivot knee system is designed to answer the limitations of traditional implants by delivering superior flexion stability, anatomic motion, and wear–limiting design characteristics.

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The Evolution® medial-pivot knee system is built upon a legacy of 95% patient satisfaction with 98.8% survivorship at 17 years1, and features a design that enhances quadriceps efficiency, allowing for improved proprioception and more normal feeling knee.

Evolution® knee with NitrX™ coating

The Evolution® knee with NitrX™ coating promotes natural kinematics with the added benefit of a Titanium Niobium Nitride Coating.

Evolution® knee with NitrX™ coating
Evolution® Medial-Pivot Knee System Evolution Nitr X Sideview 540x300 1

Evolution® knee with NitrX™ coating

The Evolution® knee with NitrX™ coating features a titanium niobium nitride (TiNbN) coating that has been shown to reduce the release of cobalt (Co), chromium (Cr), nickel (Ni), and molybdenum (Mb) ions common in standard CoCr implants.7 The Evolution® knee with NitrX™ coating maintains the kinematic benefits of the medial-pivot design8, resulting in optimal stability.9

Evolution® Cemented Knee Systems

The Evolution® medial-pivot knee system delivers flexion stability, anatomic motion, and a wear–limiting design.

Evolution® Medial-Pivot Knee System Evolution mp knee exploded 1


To achieve postoperative satisfaction, patients want their implant to deliver high functionality and a more natural feeling. The single-radius design of the Evolution® knee system provides stability through all phases of flexion. AP translation is also decreased to help achieve a more normal feel. This represents a dramatic advance over traditional knee replacements, which have been shown to exhibit anterior-posterior translation that can decrease stability and cause early revisions.2,3


“The return of range of motion is much faster, they get much better motion and they get it quicker. They're out of the hospital sooner, their pain is better and they seem to get back to the activities that they want to do at a much quicker rate.”

- Dr. Joseph Assini MD, Englewood, CO


Why set out to design a better knee system? Today, according to the latest literature, nearly 20% of all patients are unhappy with their total knee replacement due to residual pain, functional issues and early implant failure.8

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The Evolution® medial-pivot knee system enhances quadriceps efficiency and reduces the quadriceps avoidance found in traditional knee replacements. By enhancing quadriceps efficiency, the patient can have increased proprioception and a more normal feeling knee.10

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The Evolution® medial-pivot insert features an anterior raised lip, to replicate the function of the PCL, and a posterior raised lip, to replicate the function of the ACL, acting like an ACL-PCL substituting knee.

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In-vivo long-term clinical studies have consistently shown that medial-pivot design achieves equal or higher degrees of flexion than traditional posterior stabilized (PS) knee design, with an average of 124°.11;12-13

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It is routine for patients to complain of instability following a traditional knee replacement. Studies also clearly show instability to be the leading cause of early revisions.4-6 By delivering a more secure, highly conforming articulation, the Evolution® medial-pivot knee system provides the kind of stability throughout the range of motion that patients seek.

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Flexion stability

• Promoted through high medial conformity and constant radius spherical condyles.

• Increased flexion and enhanced quadriceps efficiency achieved through longer constant flexion radius with more posterior, medial dwell point

Anatomic motion

• Driven through a stable medial compartment and a mobile lateral compartment that rotates or pivots about the medial.

Wear-limiting design14-21

• Enabled through a maximized contact area and repeatable motion path that minimizes contact stresses.


  1. Macheras GA et al A long term clinical outcome of the Medial Pivot Knee Arthroplasty System. Knee. 2017 Mar;24(2):447-453
  2. Dennis DA, Komistek RD, Mahfouz MR, Haas BD, Stiehl JB. Multicenter determination of in vivo kinematics after total knee arthroplasty. Clin Orthop Relat Res. 2003
  3. Schmidt R, Komistek RD, Blaha JD, Penenberg BL, Maloney WJ. Fluoroscopic analyses of cruciate-retaining and medial pivot knee implants. Nov;(416):37-57.
  4. Walker PS. Factors affecting the impingement angle of fixed- and mobile bearing total knee replacement, a laboratory study. J Arthroplasty.2007;22(5):745-52.
  5. Bindleglass DF. Current principles of design for cemented and cementless knees. Tech Orthop. 1991;6:80.
  6. Banks S. Knee motions during maximum flexion in fixed and mobile-bearing arthroplasties. Clin Orthop Relat Res. 2003;410:131-8.
  7. MPO Data on file
  8. Dennis DA, Komistek RD, Mahfouz MR, Haas BD, Stiehl JB. Multicenter determination of in vivo kinematics after total kneearthroplasty. Clin Orthop Relat Res. 2003
  9. Freeman MA, Pinskerova V. The movement of the knee studied by magnetic resonance imaging. Clin Orthop Relat Res. 2003;410:35-43
  10. LaMontagne M, et al. Quadriceps and Hamstring Muscle Activation and Function Following Medial Pivot and Posterior Stabilized TKA: Pilot Study
  11. Blaha J. The rationale for a total knee implant that confers anteroposterior stability throughout range of motion.
  12. Karachalios Th et al. An 11- to 15- year clinical outcome study of advance medial pivot knee arthroplasty. Bone Joint J 2016
  13. Van Overschelde P, Parker A Preliminary Short-term Outcome of first 300 consecutive cases of second generation Medial-Pivot Total Knee replacement System EKS Arthroplasty Conference - eposter - London - April 20-21, 2017
  14. McEwen H. The influence of design, materials, and kinematics on the in vitro wear of total knee replacements. J Biomech. 2005;38:357-65.
  15. Schwenke T. Differences in wear between load and displacement control tested total knee replacements. Wear. 2009;267:757-62.
  16. Haider H. Comparison between force-controlled and displacement controlled in-vitro wear testing on a widely used TKR implant. ORS Poster. 2002;27:1007.
  17. Muratoglu O. Metrology to quantify wear and creep of polyethylene tibial knee inserts. Clin Orthop Relat Res. 2004;428:114-9.
  18. Wang A. Mechanistic and morphological origins of UHMWPE wear debris in total joint replacement pros theses. Proc Inst Mech Eng. 1996;210(3):141-55.
  19. Bragdon C. The importance of multidirectional motion on the wear of polyethylene. Proc Inst Mech Eng. 1996;210(3):157-65.
  20. Landy M. Wear of UHMWPE components of 90 retrieved knee prostheses. J Arthroplasty;1988;3:73-85
  21. Baker, P.N., et al.The role of pain and function in determining patient satisfaction after total knee replacement. JBJS.2007.89(7):p893-900.