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Avoid Internal Rotation of Tibial Component



- See:
  - Internal Rotation of Knee Joint:
  - Rotation of Tibial Component:
- Correct Rotation:
 - as a general rule, the tibial componenet should be aligned such that it points to the medial third of the tibial tubercle;
 - correct rotational positioning of tibial component is best achieved by by aligning intercondylar eminennce of tibial component w/ tibial
     crest in the saggital plane;
     - in making tibial cuts, care must be exercised when using such system because of the asymmetry of the plateaus;
     - AP length of the medial condyle is considerably larger;
- Tendency for Internal Rotation:
  - tendency to internally rotate tibial cut is present in many systems becuase of laterally dislocated extensor mechanism & physical
      retraction by assistant tends to externally rotate flexed tibia;
  - internal rotation of cut is be avoided particularly in systems that incorporate a significant Posterior Slope, because this will produce a
       lateral tilt;
  - jig systems fitted to anterior surface of proximal tibia will have tendency to align in excessive internal rotation because of everted patella 
      tendon laterally;
  - 2 mechanisms can be used to avoid this tendency to internal rotation;
      - look down on tibial plateau and cutting jig w/ knee in flexion;
      - face of jig should be parallel to the plane of femoral condyles;
- Effect on Patella:
 - internal Rotation of tibial component is a common error, & causes lateral displacement of tibial tubercle, which increases Q angle and 
      increases the risk of patellar instability & dislocation;
      - medially rotated tibial & femoral components have a high incidence of assoc postop patellar dislocation