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eMP™ Knee System

eMP™ Knee System

MEDIAL-PIVOT KNEE

eMP™ Knee System

The difference is in the design.

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.

The eMP™ Knee System is designed to answer the limitations of traditional implants by delivering superior flexion stability, anatomic motion, and wear –limiting design characteristics.
 
 

    Natural Design

    Stable Motion.
    Normal Function.
    Natural Feel.

    The Medial-Pivot Knee is uniquely engineered to reproduce a healthy knee’s stability and motion. With a stable, pivoting medial side and a lateral side that rolls forward or backward throughout flexion, the eMP Knee System is designed to feel and function like a natural knee.

      ACL-PCL Substituting

      High Conformity.
      Constant Radius.
      Unique Design.

      The Medial-Pivot Knee features a highly conforming medial side that results from a constant radius design. Reproducing the natural function and stability of the ACL and PCL, this design is unique from every other less conforming traditional knee system. It gives the Medial-Pivot Knee natural motion, so it feels more like a normal knee.
        Natural Knee

         
        eMP Knee System

        Enhanced Quad Efficiency

        Better Quad Force.
        Better Function.
        Postional Awareness.

        With a more normal quadriceps force pattern, patients not only enjoy improved functionality but also more natural feeling. By reducing quadriceps avoidance, the highly conforming design of the eMP™ System enhances quadriceps efficiency and reduces problems common in traditional knee replacements. This can actually increase patient proprioception or awareness of the knee’s position, and uniquely create a more normal, natural feeling.1, 2
          Shapes, Structures and Movements of the Natural Knee

          References

          1. Li K, et al. Trunk muscle action compensates for reduced quadriceps force during walking after total knee arthroplasty. Gait Posture. 2013 May; 38(1):79-85.
          2. LaMontagne M, et al. Quadriceps and Hamstring Muscle Activation and Function Following Medial Pivot and Posterior Stabilized TKA: Pilot Study


          FLEXION STABILITY

          Overview

          Patient Satisfaction.
          Single Radius Design.
          Superior Stability.

          To achieve postoperative satisfaction, patients want their implant to deliver high functionality and a more natural feeling. The single-radius design of the eMP™ 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.1, 2

            High Conformity

            High Conforming Articulations.
            Stable Range of Motion.
            Fewer Revisions.

            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.3-5 By delivering a more secure, highly conforming articulation, the eMP™ Knee System provides the kind of stability throughout the range of motion that patients seek.
             

              Constant Radius

              Natural Biomechanics.
              Anterior-Posterior Stability.
              Greater Clinical Functionality.

              With a constant radius design, the eMP™ Knee System gives patients a more stable feeling and more normal biomechanics. The constant radius in both the coronal and sagittal planes is uniquely designed to mimic the movement of the natural knee. This is a significant benefit over traditional multi-radius implants, which are typically less stable and fail to deliver the same natural feeling to the patient.

              With a constant radius femoral component featuring a highly congruent tibial insert, the eMP™ Knee System also delivers superior stability in mid-flexion and prevents anterior-posterior translation. The simple result is that the eMP™ constant radius knee design has been documented in literature to achieve higher clinical function than competitive multi-radius designs.

                Enhanced Quad Efficiency

                Reduce Quadriceps Avoidance.
                Prevent Altered Gait.
                Achieve Normal Feeling.

                On the heels of a knee replacement, patients often suffer from changes to muscle contribution to such extent that it alters their gait. Center-of-mass acceleration can also be affected. To compensate, patients typically lean forward and use their hamstrings over their quads, which produces a common “quadriceps avoidance” gait.7

                The innovative design of the eMP™ Knee System delivers a more normal quadriceps force pattern. The result is a positive effect on knee function. It delivers enhanced quadriceps efficiency and reduces the quadriceps avoidance found in traditional knee replacements, so patients can enjoy increased proprioception and more normal feeling.7, 8

                  References

                  1. 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
                  2. Schmidt R, Komistek RD, Blaha JD, Penenberg BL, Maloney WJ. Fluoroscopic analyses of cruciate-retaining and medial pivot knee implants. Nov;(416):37-57.
                  3. Iorio R et al. Comparison of the hospital cost of primary and revision total knee arthroplasty after cost containment. Orthopedics. 1999 Feb;22(2):195-9
                  4. Firestone T. Surgical management of symptomatic instability following failed primary total kneereplacement. J Bone Joint Surg; 2006, 83(4):80-4
                  5. Blaha D. Kinematics of the knee and total knee prosthesis design. J Bone Joint Surg Br 2002 Vol. 84-Bno. SUPP I 75-i-76
                  6. Ezechieli M. The influence of a single-radius design on the knee stability. Technol Health Care; 2012, 20(6): 527-34
                  7. Li K, et al. Trunk muscle action compensates for reduced quadriceps force during walking after total knee arthroplasty. Gait Posture. 2013 May; 38(1):79-85.
                  8. LaMontagne M, et al. Quadriceps and Hamstring Muscle Activation and Function Following Medial Pivot and Posterior Stabilized TKA: Pilot Study


                  ANATOMIC MOTION

                  Overview

                  Feels Normal.
                  Behaves Naturally.
                  Functions Like the Human Knee.

                  With the increasingly active lives of patients today, they have come to demand and expect an implant that feels normal and behaves naturally. The eMP™ Knee System has uniquely designed structures, contours and movements that look, feel and function like the human knee. This is in stark contrast to traditional knee replacements that do not possess design features similar to the human knee, and thus do not reproduce performance that feels like a natural knee.

                  Equally important and essential to a normal feeling replacement is the eMP™ Knee System global sizing profile. It helps assure a more natural fit that promotes normal feeling functionality and higher quality of life.

                    Natural Function

                    Normal Motion.
                    Natural Feeling.
                    Unique Asymmetric Design.

                    A driving force behind the design of the eMP™ Knee System was creating a replacement that performs and feels as natural as possible. The eMP™ insert is designed to allow normal motion and natural function by incorporating asymmetric design features that closely resemble the human knee.1

                      Normal Feeling

                      Replicates ACL and PCL.
                      Preferred Over All Other Designs.
                      More Natural Feeling.

                      One reason patients can tell the difference between their natural knee and a replacement is soft tissue. One study found that our Medial-Pivot design, which effectively substitutes for the ACL and PCL, is strongly preferred over all other designs (CR, PS, and Mobile-Bearing).2

                      The eMP™ tibial insert features a high anterior and posterior lip which substitutes for both cruciate ligaments and delivers a more normal feeling for the patient. The result is a more natural feeling for patients that increases proprioception.2

                        Global Sizing Profile

                        Global Sizing Profile.
                        Maximized Surface Coverage.
                        A Fit For Every Patient.

                        With the eMP™ Knee System’s Global Sizing Profile, there is an implant for every patient. The system has eleven anatomic tibial base profiles and eight femoral sizes to maximize coverage and best fit patients of both genders and multiple ethnicities.

                        Multiple literature sources provide evidence that optimal tibial implant coverage and implant fit contribute to optimal flexion kinematics.3-5 And not only does a better fitting implant function better, but patient satisfaction is routinely greater as well.

                          References

                          1. Blaha J. The rationale for a total knee implant that confers anteroposterior stability throughout range of motion. J Arthroplasty. 2004;1(4):22-26.
                          2. Pritchett J. Patients prefer a bicruciate-retaining or the medial-pivot total knee prosthesis. J Arthroplasty. 2011; 26(2):224-8.
                          3. 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.
                          4. Bindleglass DF. Current principles of design for cemented and cementless knees. Tech Orthop. 1991;6:80.
                          5. Banks S. Knee motions during maximum flexion in fixed and mobile-bearing arthroplasties. Clin Orthop Relat Res. 2003;410:131-8.

                           


                          WEAR LIMITING DESIGN

                          Overview

                          Durable Design.
                          Lower Wear Potential.
                          Repeatable Motion Path.

                          In addition to a high-functioning knee, patients consistently demand a durable and long lasting implant. The design of the eMP™ Knee System has been shown to have a lower wear potential in a comparative aspiration study.1-4 One reason for this superior wear characteristic is the repeatable motion path and minimized contact stresses.5-7

                            Minimizes Contact Stresses

                            Maximum Contact Area.
                            Reduced Wear Forces.
                            Longer Implant Survivorship.

                            By maximizing the contact area in the eMP™ Knee System with design features like high tibiofemoral conformity, wear forces have been minimized throughout the range of motion (ROM). The end result is longer implant survivorship and greater patient satisfaction.1, 8, 9

                              Repeatable Motion

                              Stable Even Under Stress.
                              Resists Multi-Directional Motion.
                              Same Kinematics as the Natural Knee.

                              Traditional knee implants can suffer from multi-directional motion when under stress such as going down stairs. This instability can cause the femoral component to exhibit anterior and posterior translation. The excessive sliding between the components can significantly increase the wear rate on traditional implants.4,5,10,11

                              This problem is eliminated by the eMP™ Knee System. It is designed to move in a repeatable motion path. This not only reproduces the kinematics of the natural knee for greater patient comfort, but resists the multi-directional motion often occurring in traditional knee replacements.5, 10-13

                               

                                References

                                1. McEwen H. The influence of design, materials, and kinematics on the in vitro wear of total knee replacements. J Biomech. 2005;38:357-65.
                                2. Schwenke T. Differences in wear between load and displacement control tested total knee replacements. Wear. 2009;267:757-62.
                                3. Haider H. Comparison between force-controlled and displacement controlled in-vitro wear testing on a widely used TKR implant. ORS Poster. 2002;27:1007.
                                4. Muratoglu O. Metrology to quantify wear and creep of polyethylene tibial knee inserts. Clin Orthop Relat Res. 2004;428:114-9.
                                5. 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.
                                6. Bragdon C. The importance of multidirectional motion on the wear of polyethylene. Proc Inst Mech Eng. 1996;210(3):157-65.
                                7. Landy M. Wear of UHMWPE components of 90 retrieved knee prostheses. J Arthroplasty;1988;3:73-85.
                                8. Data on file at MicroPort Orthopedics.
                                9. Zimmer NexGen® Complete Knee Solutions CR-FLEX and LPS-FLEX Knee System 97-0000-601-00.
                                10. Komistek R. In vivo fluoroscopic analyses of the normal human knee. Clin Orthop Relat Res. 2003;410:69-81
                                11. Schmidt R. Fluroscopic analyses of cruciate-retaining and medial-pivot knee implants. Clin Orthop Relat Res. 2003;410:139-147.
                                12. Bindeglass DF. Current principles of design for cemented and cementless knees. Tech Orthop. 1991;6:80.
                                13. Sathasivam S, Walker PS. Optimization of the Bearing Surface Geometry of Total Knees. J Biomechanics. 1994;27(3):255-64
                                14. Data on file at MicroPort Orthopedics.
                                15. Bindeglass DF. Current principles of design for cemented and cementless knees. Tech Orthop. 1991;6:80.