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Hamelynck Kj. Stability Of The Knee, A Dynamic Concept

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Hamelynck Kj. Stability Of The Knee, A Dynamic Concept

  1. 1. STABILITY OF THE KNEE A dynamic concept KJ Hamelynck Amsterdam/Roma
  2. 2. “ Why are total knee arthroplasties failing today?” Peter F. Sharkey, MD; William J. Hozack, MD; Richard H. Rothman, MD, PhD; Shani Shastri, MD; Sidney M. Jacoby, BA Clinical Orthopaedics and Related Research , november 2002 pag 7-14
  3. 3. “ 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
  4. 4. <ul><li>Stability of the normal knee </li></ul><ul><li>intrinsic stability </li></ul><ul><li>. geometry of surfaces </li></ul><ul><li>. menisci </li></ul><ul><li>extrinsic stability </li></ul><ul><li>. ligaments </li></ul><ul><li>. posterior capsula </li></ul>
  5. 5. <ul><li>The normal knee demonstrates 3 rotations </li></ul>int/ext rotation ad/abduction flexion/extension
  6. 6. <ul><li>The normal knee demonstrates 3 translations </li></ul>medial/lateral superior/inferior anterior/posterior
  7. 7. Forced internal/external rotation Blankevoort et al., J Biomech 1988 moment 3 external rotation -3 moment [Nm] internal rotation -30 º 30 º
  8. 8. Flexion and internal/external rotation Blankevoort et al., J Biomech 1988 External rotation Internal rotation Flexion 160 º 140 º 120 º 100 º 80 º 60 º 40 º -20 º 20 º -30 º -20 º -10 º 10 º 20 º 30 º
  9. 9. Flexion and internal/external rotation Blankevoort et al., 1988; Van Kampen, thesis 1987 External rotation Internal rotation Flexion 160 º 140 º 120 º 100 º 80 º 60 º 40 º -20 º 20 º -30 º -20 º -10 º 10 º 20 º 30 º
  10. 10. Flexion & rotation during gait M.A. Lafortune et al., J Biomech 1992
  11. 11. External rotation Internal rotation Flexion 80 º 60 º 40 º - 20 º 20 º -20 -10 º 10 º 20 º Flexion & rotation during gait M.A. Lafortune et al., J Biomech 1992 Swing phase Toe off Heel strike Stance phase
  12. 12. The envelope of passive motion M.A. Lafortune et al., J Biomech 1992 External rotation Internal rotation Flexion 160 º 140 º 120 º 100 º 80 º 60 º 40 º -20 º 20 º -30 º -20 º -10 º 10 º 20 º 30 º Swing phase Stance phase
  13. 13. <ul><li>varus stress </li></ul><ul><li>and stabilisation by ligaments and posterior capsule </li></ul><ul><li>lateral stability </li></ul><ul><li>5 0 of flexion 25 0 of flexion </li></ul>
  14. 14. <ul><li>valgus stress </li></ul><ul><li>and stabilisation by ligaments and posterior capsule </li></ul><ul><li>medial stability </li></ul><ul><li>5 0 of flexion 25 0 of flexion </li></ul>
  15. 15. <ul><li>Forces conducted through the ligaments </li></ul>80 20 100 20 Stair descending 60 10 275 6 Stair ascending 60 20 60 100 Ramp descending 100 15 140 15 Ramp climbing 50 20 80 40 Level walking LCL MCL PCL ACL
  16. 16. <ul><li>Stability of the knee </li></ul><ul><li>compressive, torsional and shear forces loading forces </li></ul><ul><li>are between 2 and 7x body weight during adl-activities </li></ul><ul><li>force </li></ul>
  17. 17. <ul><li>Stability of the knee </li></ul><ul><li>ligaments are prividing some stability </li></ul><ul><li>muscle force and gravitational forces are providing </li></ul><ul><li>the real stability </li></ul><ul><li>ligaments become recruted when </li></ul><ul><li>motion tries to exceed the limits </li></ul><ul><li>of the envelope of passive motion </li></ul>
  18. 18. <ul><li>Stability of the normal knee </li></ul><ul><li>muscle force </li></ul>
  19. 19. <ul><li>How do ligaments work ? </li></ul><ul><li>propriocepsis </li></ul>
  20. 20. <ul><li>What happens during total knee replacement ? </li></ul><ul><li>articular surfaces removed </li></ul><ul><li>cruciate ligaments resected </li></ul><ul><li>> the knee de-stabilized </li></ul><ul><li>What happens if further </li></ul><ul><li>release of a collateral </li></ul><ul><li>ligament is performed ? </li></ul>
  21. 21. <ul><li>After total knee replacement </li></ul><ul><li>what happens with the </li></ul><ul><li>collateral ligaments ? </li></ul>
  22. 22. <ul><li>Without well functioning ligaments </li></ul><ul><li>> the amount of proprioceptiv information </li></ul><ul><li>diminished </li></ul><ul><li>> the envelope of passive motion widened </li></ul><ul><li>> disturbance of dynamic stabilization ! </li></ul><ul><li>More intrinsic constraint makes it worse !!! </li></ul>
  23. 23. <ul><li>To create good stability of the replaced knee </li></ul><ul><li>> maintain the collateral </li></ul><ul><li>frame ! </li></ul><ul><li>> don’t perform release of </li></ul><ul><li>a collateral ligament ! </li></ul><ul><li>Think about the dynamic stability of the knee </li></ul>

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