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Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland

TOTAL KNEE ARTHROPLASTY. Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland. Total Knee Arthroplasty. Goal Restore mechanical alignment Restore joint line. Normal Knee Anatomy. Position in single leg stance Mechanical axis valgus 3º Femoral shaft axis valgus 6º

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Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland

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  1. TOTAL KNEE ARTHROPLASTY Frank R. Ebert, MDUnion Memorial HospitalBaltimore, Maryland

  2. Total Knee Arthroplasty • Goal • Restore mechanical alignment • Restore joint line

  3. Normal Knee Anatomy • Position in single leg stance • Mechanical axis valgus 3º • Femoral shaft axis valgus 6º • Proximal tibia varus 3º

  4. Total Knee Arthroplasty • Radiographic Evaluation • Standing full length – AP • Standing AP • Extension/Flexion laterals • Tunnel view • Sunrise view

  5. Total Knee Arthroplasty • Radiographic Evaluation • Weight Bearing X-rays • Extent of joint space narrowing • Ligament stretch out • Subluxation of femus on tibia

  6. Total Knee Arthroplasty • Radiographic Analysis • Anatomic Axis – Femur • Line that bisects the medullary canal of the femur • Determines the entry point of the femoral medullary guide rod

  7. Total Knee Arthroplasty • Radiographic Analysis • Mechanical Axis – Femur (MAF) • A line from center of femoral head to center of distal femur

  8. Total Knee Arthroplasty • Radiographic Analysis • Anatomic Axis Tibia (AAT) • A line that bisects the medullary canal of the tibia • Determines the entry point of the guide rod

  9. Total Knee Arthroplasty • Radiographic Evaluation • Mechanical Axis – Tibia (MAT) • Line from center of proximal tibia to center of ankle • Proximal tibia is cut perpendicular to (MAT)

  10. Issues with Surgical Techniques • Traditional Joint Line Orientation • Tibial cut perpendicular to the MAT • Femoral shaft at a valgus angle 5º to 8º valgus based off the ong standing x-ray

  11. Surgical Technique • Incision — straight longitudinal incision • Tissue handling key • Avoid flaps • Preserve soft tissue flap about the patella

  12. Surgical Technique • Remember 7cm Rule between incisions

  13. Exposure options — Subvastus / midvastus u Routine knee replacements z Quicker rehab — Medial parapatellar / midline u Difficult total knee — obese patients u Revisions Issues with Surgical Techniques

  14. MIS vs MINI TKA • Capsulotomy only? • Mid vastus? • Sub vastus? MIS

  15. MIS vs MINI TKA • Mid vastus? • Sub vastus? • Quad sparing? MIS

  16. Anatomic Variations of VMO Insertion Type I-High Insertion Area of Variation Type II-Pole Insertion Type III-LowInsertion

  17. Type I- High VMO Insertion Area of extended retinaculum Muscle Insertion Retinacular Incision

  18. Type II-Pole Insertion Capsular or Retinacular Incision Muscle Insertion

  19. Type III-Low VMO Insertion Area of Extended VM Muscle Insertion

  20. Issues with Surgical Techniques • Alignment • Extramedullary vs Intramedullary •  Accuracy vs increased PE risk •  Femur – Intramedullary • z Overdrill opening and insert slowly IM guide • z Caution with bilateral Total Knee Arthroplasty •  Tibia – Extramedullary

  21. Issues with Surgical Techniques • Femoral Rotation • Landmarks • Posterior femoral condyles • Epicondyles 5º external rotation to the posterior condyles

  22. Issues with Surgical Techniques • Femur • Measured resections: equal bone distally and posteriorly • Tensioning devices & ligament releases • Do not alter bone resection for ligament tightness

  23. Issues with Surgical Techniques • Tibial Component Rotation • Transmalleolar axis • Posterior tibial plateau • Tibial tubercle — lies lateral

  24. Malalignment • Tibial Component • Internally Rotated • Tubercle Too Lateral

  25. Management of Deformity • 1. Release the tight side of the deformity • 2. Tighten the loose side • 3. Accept some residual soft tissue imbalance • 4. Combination

  26. Surgical Techniques • Varus Knee • 1. Pes anserinus • 2. Joint Capsule • 3. Deep Tibial Collateral • 4. Semimembranosus • 5. Posterior Medial Capsule

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