Stiehl Jb. Design Factors Influencing Rom In Tka

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Stiehl Jb. Design Factors Influencing Rom In Tka

  1. 1. Design Factors Influencing Range of Motion in TKA James B. Stiehl, MD Medical College of Wisconsin Milwaukee, Wisconsin
  2. 2. Factors Determining ROM in TKA <ul><li>Preoperative ROM and body habitus </li></ul><ul><li>Prior surgery or trauma </li></ul><ul><li>Surgical technique </li></ul><ul><li>Postoperative pain and scarring problems </li></ul><ul><li>Prosthetic Design </li></ul>130
  3. 3. Patient Factors: Obesity <ul><li>Flexion > 120°; 7% obese </li></ul><ul><li>Flexion 101° to 119°; 28% obese </li></ul><ul><li>Flexion < 100°; 78% obese </li></ul><ul><ul><ul><li>Shoji,et.al. Orthopaedics, 1990 </li></ul></ul></ul><ul><li>Flexion>130  Kinemtics Driven by Thigh Contact </li></ul>
  4. 4. Active vs Passive Range of Motion in TKA <ul><li>Weight bearing flexion < Passive flexion in Normal, PCR, PS (P<.045) </li></ul><ul><li>Active Flexion: Normal-135°; PCR-103°;PS-113° </li></ul><ul><li>PS > PCR Active Weight Bearing (P<.025) </li></ul><ul><ul><ul><ul><li>Dennis, et.al., Jl Arthroplasty,1998 </li></ul></ul></ul></ul>
  5. 5. Balanced Flexion Gap <ul><li>Posterior condylar reference (0° ER): 120° Preop to 100° Postop (PCR) </li></ul><ul><li>Posterior condylar reference (~3° ER): 115° Preop to 112° Postop (PS) </li></ul><ul><ul><ul><li>Laskin, et.al., Jl Arthroplasty, 1995 </li></ul></ul></ul>
  6. 6. Tibia Cut First Surgical Technique <ul><li>Anterior Femoral Cortical Reference </li></ul><ul><li>Flexion Space: Tension Adjustment </li></ul><ul><li>Distal Femoral Cut Last </li></ul><ul><li>Standard Revision Arthroplasty Method </li></ul>
  7. 7. Kinematic “Conflict”, circa 2007 <ul><li>Absent ACL Causes Loss of “Rollback” </li></ul><ul><li>True for Unicondylar, Bicruciate, Cruciate Retaining, and “Total Condylar” Rotating Platform </li></ul><ul><li>Anterior Translation exaggerated by Flexion Laxity </li></ul><ul><li>? Effect of Joint Line Elevation, but may tend to tighten extensor mechanism </li></ul><ul><li>PS drives “roll back” and higher flexion </li></ul><ul><ul><ul><ul><ul><li>Dennis, et.al., Knee Society, 2003 </li></ul></ul></ul></ul></ul>
  8. 8. LCS Design Issues for ROM <ul><li>Neutral to Anterior Starting Position </li></ul><ul><li>Early “Rollback” for BCR, PCR, and RP </li></ul><ul><li>“ Slide Forward” seen in deep flexion in virtually all cases (120  Limit) </li></ul><ul><li>Lack ACL Function </li></ul><ul><ul><ul><li>Stiehl, et.al. “LCS Moble Bearing TKA”,2002, Springer </li></ul></ul></ul>
  9. 9. LCSPS Design Flaws
  10. 10. LPS High Flex TKA <ul><li>Posterior Stabilized Design: “ROLLBACK” </li></ul><ul><li>Augmented Posterior Condyles: + 2MM </li></ul><ul><li>Patellar Cutout to prevent impingment </li></ul><ul><li>Spine/Cam: Low contact point, Higher spine, Extended articulation posterior </li></ul>
  11. 11. LPS Design Considerations Longer Cam; Posterior Condyle 2mm > LPS High Flex LPS
  12. 12. Patellar Impingement Impingement LPS LPS High Flex
  13. 13. LPS High Flex Mobile ROM <ul><li>102 TKA; Age 66 ave.(43 to 80); Wt- 72 Kg ( 36 to 110) </li></ul><ul><li>Varus Deformity: Ave 9 ° (Range 4° to 20°) </li></ul><ul><li>Valgus Deformity: Ave 6°(Range 1° to 11°) </li></ul><ul><li>Postop Femorotibial Angle: 2° Valgus (Range 1° to 5°) </li></ul><ul><li>Preoperative Flexion: 120° ( 90° to 140°) </li></ul><ul><li>Postoperative Flexion: 131° (90° to 150°) </li></ul><ul><ul><ul><ul><ul><li>Argenson, et.al., ISK Fall Meeting, 2003 </li></ul></ul></ul></ul></ul>
  14. 14. Literature Review: PS vs PS Flex <.05 135  120  50 Weeden, et.al. =0.41 138  135  50* Kim, et.al. <.05 138  126  50 Huang, et.al. <.05 129  124  180 Bin, et.al. SD PS High Flex PS N Author
  15. 15. Kinematics of LPS High Flex <ul><li>Cadaver Test: (n=13) </li></ul><ul><li>Quads force 400 N; Hamstring force 200 N </li></ul><ul><li>Spine/Cam engagement: 80  to 135  </li></ul><ul><li>Soft Tissues Active >135  </li></ul><ul><li>Medial Rollback: 2.3 mm </li></ul><ul><li>Lateral Rollback: 3.2 mm </li></ul><ul><ul><ul><ul><li>Li, et.al. JBJS 86A: 1721 </li></ul></ul></ul></ul>
  16. 16. Kinematics of LPS High Flex <ul><li>20 Subjects; invivo fluoroscopy </li></ul><ul><li>Weight Bearing Deep Knee Bend:125  </li></ul><ul><li>Average 4.4 millimeters Rollback </li></ul><ul><li>Average 4.9  Internal Rotation </li></ul><ul><ul><ul><ul><li>Argenson, et.al. J Biomechanics 38: 277, 2005 </li></ul></ul></ul></ul>
  17. 17. LPS High Flex Mobile Results 150 ° Passive Flexion
  18. 18. LPS High Flexion Sitting 9 Inch Stool, >135 ° Flexion
  19. 19. LPS High Flex- Down Stairs
  20. 20. LCS Versus LPS High Flex in Passive Flexion Left- LPS High Flex- 115  Right- LCS - 105 
  21. 21. What Do I Tell My Patients? <ul><li>Preoperative Range of Motion of 90 ° probably improves 15-25° </li></ul><ul><li>Stair function, sitting, and exercycle requires > 110° Flexion </li></ul><ul><li>Certain patients have painful knees and will not improve (about 1 of 20) </li></ul><ul><li>LPS High Flex, properly done, may flex 130° to 140° in many cases!! </li></ul><ul><li>This may be best in patients over 65-70. </li></ul>
  22. 22. Is There A Liabilty to High Flexion in TKA <ul><li>Yes, Yes, and YES!!! </li></ul><ul><li>The mechanical forces in high flexion are EXTREME, 40-60 mPascals on Poly </li></ul><ul><li>Forces may exaggerate post wear and potential failure </li></ul><ul><li>Chronic synovitis and anterior knee pain seem to be more common in these patients. (Now AVOID Patella resurface) </li></ul>
  23. 23. CONCLUSION <ul><li>PostOP Flexion is multifactorial </li></ul><ul><li>Surgical Technique and Design are important </li></ul><ul><li>PS Option Best in Low Demand; ??? High forces on poly in flexion </li></ul><ul><li>LPS High Flex offers predictably higher flexion!! </li></ul>
  24. 25. Detrimental Kinematics Of A Flat on Flat Condylar TKA Stiehl, CORR, 1999 Medial Condyle Lateral Condyle
  25. 26. LPS High Flex on Stairs
  26. 27. Functional Outcome after TKA <ul><li>67 ° Swing phase of gait </li></ul><ul><li>83° Ascend stairs </li></ul><ul><li>93° Rise from seated position </li></ul><ul><li>100° Average PCR TK(Dennis) </li></ul><ul><li>110° Average MB TKA(Stiehl,et.al.) </li></ul><ul><li>115° Average PS TKA </li></ul><ul><li>125° Average PS Extended condyle </li></ul>
  27. 28. LPS High Flex Walking
  28. 29. LCS PS Mobile Bearing TKA
  29. 30. Clinical Experience With LCSPS (Stiehl) <ul><li>1998-1999 </li></ul><ul><li>Early Range of Motion  in ~25% (115 ° to 135 °) vs RP </li></ul><ul><li>Nontraumatic hemarthrosis- over 20% </li></ul><ul><li>8 of 110 revised to standard RP insert under 2 year FU </li></ul><ul><li>2 Femoral Loose!! </li></ul>

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