Downloaded 558 times
Uploaded byorthoprince
Biomech of Knee & tkr knee
This document discusses the biomechanics of the normal and replaced knee. It covers the axes of motion of the lower limb, tibiofemoral motion including flexion, extension, rotation, and stability mechanisms like muscles, ligaments, and menisci. It then discusses the goals and designs of total knee replacements, including whether to retain or sacrifice the cruciate ligaments, the use of cam and spine mechanisms to substitute for the PCL, and considerations for femoral and tibial implant design. Recent research topics discussed include the adductor moment, rotatory knee arthritis, and the shape of the tibial plateau.
More Related Content
Similar to Biomech of Knee & tkr knee
Biomech of Knee & tkr knee
- 2.
- 4. BIOMECHANICS KNEE :Force closedmechanism HIP :Self closed mechanism
- 5. The Axis OfLower Limb •Vertical Axis •Mechanical Axis •Anatomical Axis of Femur •Anatomical Axis of Tibia
- 8. Tibio-Femoral Motion •Flexion – Extension •Abduction– Adduction •Internal – External Rotation
- 9. Instantaneous centre ofmotion FLEXION - EXTENSION
- 10. Instantaneous center pathway FLEXION- EXTENSION
- 11.
- 12.
- 13.
- 14.
- 15. FLEXION - EXTENSION Kneeglides & Slides Rocks & Rolls!
- 17. ROTATION OF KNEE •Screwhome movement •Rotation increases as knee is flexed •Arc ranges 30 – 60
- 18. Abduction - Adduction •Normalangulation of 7 Degrees with knee extended •Motion permitted by cruciate and collaterals •No movement in flexion
- 19.
- 22. Flexion - Extension •Sit& Rise from a chair 90 -110 degrees
- 23. Flexion - Extension •Descendingstairs 90 degrees
- 24. Flexion - Extension •Ascendingstairs 82 degrees
- 25. Int – ExtRotation •Normal 30-60 Degrees •13 degrees in normal walking •More in stair walking •More on rough ground walking
- 26. Loads Applied toKnee •3X - in Level Walking •4X – in Stair Climbing •Area of Contact is less in Flexion •Medial side bears more weight
- 27. STABILITY •Surface geometry •Muscles crossing thejoint •Ligaments and capsule •Menisci
- 28. SURFACE GEOMETRY Femur isconvex Tibia is concave medially Tibia is convex laterally Tibial eminence aids in stability
- 29. •Resists deforming force •Resistsslow forces •Increase joint compression •Increase stability MUSCLES
- 30. •Resists motion •Resists translatorymovement •Resists excessive rotation LIGAMENTS
- 31. •Joint conformity •Varus valgusstability •Resists translation MENISCUS
- 32. IDEAL KNEE • Extendsfully & achieves excellent stability • Flexes beyond 110 & still retains stability • Gliding and sliding occurs simultaneously • Allows more rotation as knee flexes • Articular contact maximum throughout range
- 33. • Reduplicate thefunction of menisci • Reduplicate the function of cruciates • Achieve excellent ligament balance • Have anatomic femur & tibial surface IDEAL KNEE
- 34.
- 43. RESTORATION OF MECHANICAL AXIS Perpendicularto the Mechanical & Anatomical axis of the Tibia
- 47. BIOMECHANICS OF TKR Shouldnone, one or both cruciate ligaments be sacrificed
- 48. ACL & PCLSACRIFICED • Conforming concave surface of tibia producing inherent stability • Long term results from HSS still remains the gold standard
- 49. • Limited kneemotion • Tibial component subluxated posteriorly • Stair climbing was difficult TOTAL CONDYLAR DESIGNS
- 50.
- 51. RETAIN THE PCL •PCL roll back in flexion • Roll back needs flat tibial surface
- 52.
- 53. More arcof motion Intact PCL prevents post subluxation of tibia Stability is increased Decreased interface stresses Shear forces are well tolerated RETAIN THE PCL
- 54. • Proprioception isbetter • Retention of PCL helps in maintaining the joint line RETAIN THE PCL
- 55. Why surgeon sacrifices PCL? •Minimum tibial resection • Easier surgical technique • Easier correction of deformity
- 56. PCL SUBSTITUTING KNEE • Spine &Cam mechanism • Produces roll back • Prevents posterior subluxation
- 57. • Anterior tibialsubluxation not prevented • Does not substitute collaterals • Posterior slope in tibia necessary PCL SUBSTITUTING KNEE
- 58.
- 59. PCL SUBSTITUTING KNEE • Badfor valgus knee • Wear of spine • Bone loss
- 60. Can we substitutethe PCL by ultra congruent insert ? PCL SUBSTITUTING KNEE
- 61. PCL SUBSTITUTING KNEE •Patellectomy • Old PCL injury • Over release of PCL • Inflammatory conditions ?
- 62. MENISCAL BEARING KNEE •ACL, PCL retaining • PCL retaining
- 63. ROTATING PLATFORM KNEE •Cruciate sacrificing • Spin off • Undersurface wear
- 64. FEMUR • Anatomic • Decrease radiusof curvature posteriorly
- 65. EXTERNAL ROTATION OFFEMUR
- 66. EXTERNAL ROTATION OFFEMUR
- 67. EXTERNAL ROTATION OFFEMUR
- 68. TIBIAL TRAY • Concave conforming •No rotation in extension • Intercondylar eminence to prevent translocation • Anterior Posterior margin equal height
- 69.
- 70.
- 71.
- 72. Recent thoughts… • Adductormoment • Rotatory arthritis of knee (RAK) • Does tibia really slope posteriorly?
- 73.
- 74. Rotatory Arthritis ofKnee • Deformities in Knee are triplanar – frontal, saggital & coronal • ACL ‘s role • Soft tissue involvement
- 75. Posterior slope oftibia