SøRen Toksvig Larsen. The Role Of Cas (Computer Assisted Surgery). Slide 1 39

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SøRen Toksvig Larsen. The Role Of Cas (Computer Assisted Surgery). Slide 1 39

  1. 1. Søren Toksvig-Larsen Dept Orthopedics Hässleholm Hospital Lund University Sweden The role of computer assisted surgery (CAS)
  2. 2. WHAT’S WRONG WITH THIS SCENARIO 2007? <ul><li>Orthopaedic Surgeon: </li></ul><ul><li>Mallet and a Goniometer </li></ul>
  3. 3. WHAT’S WRONG WITH THIS SCENARIO 2007?
  4. 4. introduction The purpose of modern technique: <ul><li>improve the duration of implants </li></ul><ul><li>reduce the human error </li></ul><ul><li>simplification of the surgical technique </li></ul>
  5. 5. Not necessarily make every case better <ul><li>prevent the outliers </li></ul><ul><li>explore the possibilities of enhanced </li></ul><ul><li>ROM, stability, and alignment </li></ul><ul><ul><li>knowing the functional Kinematics </li></ul></ul>
  6. 6. My background Istituti Ortopedici Rizzoli EU projects
  7. 7. CAOS Computer Assisted Orthopaedic Surgery
  8. 8. Robot surgery ” active”
  9. 9. Formula 1 Robot surgery
  10. 10. 3-D op technique
  11. 11. Problem Too troublesome Feed back systems Safety systems
  12. 13. Why continue using modern technique??
  13. 14. Who is a non-responder My problem Non responders
  14. 15. Satisfaction - TKA <ul><li>18 % were dissatisfied or uncertain </li></ul><ul><ul><ul><li>O. Robertsson et al. 2000 </li></ul></ul></ul>
  15. 16. Possible Malalignment Rotational malalignment Translational malalignment <ul><li>Varus </li></ul><ul><li>Valgus </li></ul><ul><li>Flexion </li></ul><ul><li>Extension </li></ul><ul><li>Internal rotation </li></ul><ul><li>External rotation </li></ul><ul><li>Medial </li></ul><ul><li>Lateral </li></ul><ul><li>Proximal </li></ul><ul><li>Distal </li></ul><ul><li>Anterior </li></ul><ul><li>Posterior </li></ul>CAOS 12 º freedom for each component
  16. 17. Navigation “ passive” Surgical set up
  17. 18. Navigation gives information during surgery to position the instruments and implants according the “anatomy”
  18. 19. Knee Navigation workflow HIP center
  19. 20. Knee Navigation workflow
  20. 22. NAV as other computers ” shit in, shit out”
  21. 23. Record Alignment
  22. 24. More sophisticated instruments
  23. 25. Tibia cut
  24. 26. Gap balancing/tension ?????????????
  25. 27. Navigation <ul><li>Positioning of TKA with and without navigation </li></ul><ul><ul><ul><ul><li>Sparmann et al. JBJS-Br 2003 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>improved mechanical, frontal and sagital femoral axis and frontal tibial axis </li></ul></ul></ul></ul><ul><ul><ul><ul><li>240 patients (120 CAOS, 120 conventional) </li></ul></ul></ul></ul>Fewer outliers
  26. 28. Navigation <ul><li>60 cases TKA </li></ul><ul><li>superior results for the CAOS group compared to the conventional group </li></ul><ul><li>however </li></ul><ul><li>no statistically difference for </li></ul><ul><ul><ul><li>the mechanical axis </li></ul></ul></ul><ul><ul><ul><li>the tibial axis, the femural axis </li></ul></ul></ul><ul><ul><ul><li>a tendency for valgus positioning the femural component in the CAOS group </li></ul></ul></ul><ul><ul><ul><ul><li>Miehlke et al. Z. Orthop 2001 </li></ul></ul></ul></ul>
  27. 29. TKA navigation <ul><li>A prospective randomised study </li></ul><ul><ul><li>50 TKA knees, Genesis knee </li></ul></ul><ul><ul><li>Conclusion </li></ul></ul><ul><ul><li>CAOS excellent, but not better than conventional </li></ul></ul><ul><ul><ul><ul><ul><li>J. Victor D. Hoste (Efort 2003) </li></ul></ul></ul></ul></ul>
  28. 30. TKA navigation <ul><li>A prospective randomised study </li></ul><ul><ul><li>50 knees, Genesis knee </li></ul></ul><ul><ul><li>Accuracy CAOS – excellent </li></ul></ul><ul><ul><ul><li>Outcome Conventional CAOS </li></ul></ul></ul><ul><ul><ul><li>Torniquet time 56 min 72 min p 0.002 </li></ul></ul></ul><ul><ul><ul><li>Operative time 70 min 93 min p<0.001 </li></ul></ul></ul><ul><ul><ul><li>Blood loss 3.3 g/dl 4 g/dl ns </li></ul></ul></ul><ul><ul><ul><li>Patellar alignment no tilt>5 º no tilt>5 º </li></ul></ul></ul><ul><ul><ul><li>Patellar alignment no subluxation no subluxation </li></ul></ul></ul><ul><ul><ul><li>Tibial slope 3.5 º 3 º </li></ul></ul></ul><ul><ul><ul><ul><ul><li>J. Victor D. Hoste (Efort 2003) </li></ul></ul></ul></ul></ul>
  29. 31. ???Does it matter??? <ul><li>Sample-sizes needed in prospective randomised trials </li></ul><ul><li>Detect a difference in outcome of 2.5% (i.e., 92.5 vs. 95 %) after 10 years with 80 % power at a 5 % level of significanse. </li></ul><ul><li>2000 patients are required!!! </li></ul>
  30. 32. OVERALL SYSTEM ERROR  2 mm the average difference between point distance in the virtual scene and the corresponding point distance in the real world, is given by: ACQUISITION ERROR:  1 mm errors in surface position produced by the segmentation algorithm SIMPLIFICATION ERROR: 0.4 mm ACCURACY OF THE TRACKING SYSTEM:  0.5 mm REGISTRATION ERROR:  1 mm ACCURACY OF THE POSITION SENSOR: 1.0 mm defined as the standard deviation of a set of measures with respect to the “real” value, obtained by means of a calibration instrument.
  31. 33. Intraoperative cutting errors Some of my experience using navigation Pinning the cutting block can change the position of the block 1 - 2 degree The cutting process can change the surface additional 1 - 2 degree Can partly be corrected using navigation
  32. 34. Evaluation <ul><li>Methods with a lower accuracy than the CAOS systems </li></ul>
  33. 35. z Alignment – outliers (2-D) Femural component too extended valgus positioning the femural component Less bloodloss Individuality Tibial rotation
  34. 36. So far NOT ACHIEVED But it will The purpose of modern technique: <ul><li>improve the duration of implants </li></ul><ul><li>reduce the human error </li></ul><ul><li>simplification of the surgical technique </li></ul>
  35. 37. The CAOS technique The cost-effective problems <ul><li>Longer operation time </li></ul><ul><li>Additional surgical intervention </li></ul><ul><li>Complications? </li></ul>
  36. 38. The CAOS technique The cost-effective problems <ul><li>Big investment/costs to run the equipment </li></ul><ul><li>Troublesome technique </li></ul>saved costs for revisions
  37. 39. New technique <ul><li>A new technique becames viable if it makes a process or service deliveries either </li></ul><ul><ul><li>easier </li></ul></ul><ul><ul><li>faster </li></ul></ul><ul><ul><li>cheaper </li></ul></ul><ul><ul><li>better </li></ul></ul><ul><ul><li>2 of these benefits would make a technology more popular </li></ul></ul><ul><ul><li>For arthroplasty all 4 are required??!! </li></ul></ul>

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