Hamelynck Kj. Round Table Discussion

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  • Hamelynck Kj. Round Table Discussion

    1. 1. THE FUTURE OF TOTAL KNEE REPLACEMENT
    2. 2. History of total knee replacement <ul><li>Total knee replacement was invented </li></ul><ul><li>to cure pain of arthritic knees </li></ul><ul><li>restore stability and motion </li></ul>
    3. 3. History of total knee replacement <ul><li>TKR followed two different approaches </li></ul><ul><li>Anatomic approach vs functional approach </li></ul><ul><li>(preserving soft tissues (sacrificing soft tissues) </li></ul><ul><li>and knee physiology) </li></ul><ul><li>< > </li></ul>
    4. 4. History of total knee replacement <ul><li>The anatomic approach </li></ul><ul><li>Polycentric knee (Gunston 1970) </li></ul>
    5. 5. History of total knee replacement <ul><li>The anatomic approach </li></ul><ul><li>Bi-lateral uni-compartmental components are difficult </li></ul><ul><li>to align well and difficult to fix to bone </li></ul><ul><li>Patello-femoral arthritis must be treated </li></ul><ul><li>- patellar flange on femoral component </li></ul><ul><li>- patellar component </li></ul>
    6. 6. History of total knee replacement <ul><li>Functional approach : hinge arthroplasty </li></ul><ul><li>Waldius Judet Shiers Young Guepar </li></ul>
    7. 7. History of total knee replacement <ul><li>Functional approach : hinge arthroplasty </li></ul><ul><li>Absence or substantial restriction </li></ul><ul><li>of axial or varus-valgus rotation is </li></ul><ul><li>detrimental to fixation </li></ul><ul><li>Rotational forces will be conducted </li></ul><ul><li>to the bone-prosthesis interface and </li></ul><ul><li>loosening is more likely to occur </li></ul><ul><li>Free anatomic motion is needed to preserve fixation !!! </li></ul>
    8. 8. History of total knee replacement <ul><li>Two approaches in design </li></ul><ul><li>Anatomical approach </li></ul><ul><li>just the articular surfaces were replaced or resurfaced </li></ul><ul><li>cruciate ligaments and most of the soft tissue constraints were preserved </li></ul><ul><li>implant surfaces were designed in such a manner, that a conflict with these constraints was avoided </li></ul><ul><li>Functional approach </li></ul><ul><li>the mechanics of the knee were simplified by resecting the cruciate ligaments. </li></ul>
    9. 9. History of total knee replacement <ul><li>Free anatomical motion in fixed bearing knee replacement systems is possible only when the articulating surfaces are not congruent </li></ul><ul><li>Polyethylene wear became an </li></ul><ul><li>important failure mechanism </li></ul><ul><li>of total knee prostheses, due to </li></ul><ul><li>- high contact stress on </li></ul><ul><li>- small contact areas </li></ul>
    10. 10. <ul><li>The problem of fixed bearing knee prostheses </li></ul><ul><li>minimal constraint against displacement results in small contact areas and high contact stresses > increased risk of polyethylene articulation damage. </li></ul>The LCS Story 1977-2007
    11. 11. History of mobile bearing total knee arthroplasty <ul><li>The solution of the industry </li></ul><ul><li>was compromise: creating more </li></ul><ul><li>conformity between components </li></ul><ul><li>still allowing varus-valgus rotation </li></ul><ul><li>and some axial rotation </li></ul><ul><li>For many total knee systems this situation still exists </li></ul><ul><li>today! </li></ul>
    12. 12. History of mobile bearing total knee arthroplasty <ul><li>Mobile bearings </li></ul><ul><li>> large contact areas </li></ul><ul><li>> low contact stress </li></ul><ul><li>> minimal wear </li></ul><ul><li>> free anatomical motion </li></ul><ul><li>> minimal constraint forces </li></ul><ul><li>> minimal loosening </li></ul><ul><li>> results better ? </li></ul><ul><li>> surgery more difficult ? </li></ul>
    13. 13. Total knee arthroplasty today <ul><li>Swedish Knee Arthroplasty Register </li></ul>
    14. 14. Total knee arthroplasty today <ul><li>Swedish Knee Arthroplasty Register </li></ul>
    15. 15. <ul><li>TKA has been very succesful ? </li></ul><ul><li>1% of all knee prostheses are failing every year ! </li></ul><ul><li>(Robertson, Swedish Knee Arthroplasty Register,1999) </li></ul><ul><li>  </li></ul>Total knee arthroplasty today
    16. 16. <ul><li>“ Why are total knee arthroplasties failing today?” </li></ul><ul><li>Peter F. Sharkey, MD; William J. Hozack, MD; Richard H. Rothman, MD, PhD; Shani Shastri, MD; Sidney M. Jacoby, BA . CORR Nov 2002:7-14 </li></ul>Total knee arthroplasty today
    17. 17. Total knee arthroplasty today “ Current etiologies and modes of failure in total knee arthroplasty revision” Kevin J. Mulhall, Hassan M. Ghomrawi, Sean Scully, John J. Callighan, Khaled J. Saleh Clinical Orthopaedics and Related Research 446, pg 45-50, 2006
    18. 18. <ul><li>Modes of failure </li></ul><ul><li>Surgical insufficiency is the most common </li></ul><ul><li>cause for early failure of an arthroplasty </li></ul><ul><li>Wear of polyethylene is the most important </li></ul><ul><li>reason for failure after 5 years </li></ul><ul><li>Instability has become an important reason </li></ul>Total knee arthroplasty today
    19. 19. <ul><li>Computer assisted surgery (CAS) and </li></ul><ul><li>Minimally invasive surgery (MIS) </li></ul><ul><li>are they bringing us any improvement or </li></ul><ul><li>are we performing a lot of wishful thinking ? </li></ul>Total knee arthroplasty today
    20. 20. <ul><li>What do we want ? </li></ul><ul><li>knees without pain </li></ul><ul><li>good passive and dynamic stability </li></ul><ul><li>knees with anatomic motion </li></ul><ul><li>knees with an better overall function </li></ul>Total knee arthroplasty today
    21. 21. <ul><li>How can we achieve improvement ? </li></ul><ul><li>with today’s surgery ? </li></ul><ul><li>with today’s prostheses ? </li></ul>Total knee arthroplasty today
    22. 22. Total knee arthroplasty today Do we want a rotating platform + posterior stabilisation ?
    23. 23. Total knee arthroplasty today Do we want to retain the cruciate ligaments, replace just what is needed ?
    24. 25. 1: Mechanical axis  The AP Femoral cuts are also made at right angles to the mechanical axis

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