Aims of Bone cuts:

  • Correct mechanical axis
  • Restoration joint line
  • Equalizing flexion and extension gaps
  • Balancing soft tissues
  • Correct patella-femoral knematics

2 Techniques:

Measured Resection:


  • Anatomical recostruction of the femur
  • Remove amount of bone as component thickness
  • Rotation based on anatomical landmarks


  • Maintaining joint line
  • Minimize mid-flexion instability
  • May be easier to be performed

Gap balancing technique:


  • Ligament balanced femoral resection
  • Flexion/extention gap determing distal femoral resection
  • Flexion gap determine femoral component rotation (irrispective of bone landmarks!!!)
  • Parallelism to the epycondilar axis is not the objective (+6°)

Aims of rotational positionment:

  • Avoid patellar maltracking (abnormal Q angle)
  • To achieve a simmetric flexion-extension gap
  • To achieve a more “normal” kinematics
  • To minimize instability/wear/pain

4 Techniques:

Femoral Rotation:

  • Transepincondylar Axis
  • Posterior Condylar Line
  • Balanced Flexion Gap
  • Whiteside Line
  • Functional Flexion axes

1 2

5 Ancillary Tools:

  • Conventional intra/extramedullary guide
  • Patient Specific Instrumentation
  • Computer assisted technique ( unique tool to offer to the surgeon numbers without losing his control!!)

Take home message:

  • Correct the arthri1s deformity by bone cuts
  • Remove the minimal bone stock
  • Restore the joint line
  • Balance the ligament with the same joint spaces and the prosthesis thickness
  • Do not accept passively any dogma in rota1on (do not ruotate the femur, check the piano sign…)
  • CAS tools (navigation, psi, robot,ecc.) are not a different technique but an ancillary tool for better informations about your procedure

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