Preoperative Planning of TKR-

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Preoperative Planning of TKR-Ä cookbook
approach to TotalKnee Arthoplasty is
deplorable..Dr John Insall
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Principles of Knee replacement Surgery
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Principle 1Distal femoral valgus averages nine
degrees
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(No Transcript)
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Prrinciple 2Every patients anatomy is different
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Principle 3Knee instruments were developed for
aerage anatomy
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Principle 4Resections from the distal femur
alter ligament tension in extension whereas
resections from the posterior condyles alter
ligament tension in flexion
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Principle 5 Assymetric bone resection alter
ligament balance
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Preoperative Radiiographs

• AP weight bearing radiograph with knee in maximum
  extension using 14x17cassette
• Full limb 51study if there is previious fracture
  or surgery on femur
• Table-down lateral view in 90degrees flexion for
  implant size determination

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Lateral Xrays show bone loss with OA mostly on
tibia side and PCL contracture
Lateral condlyle
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Templating Sequence

1. Define the patients anatomy- AP Xrays
2. Plan distal femoral resection- AP Xrays
3. Plan Tibial resection- AP Xrays
4. Plan posterior condyle resections- Lateral Xrays
5. Select femoral component size- Lateral Xrays
6. Plan Ligament releases- AP Xrays

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1. Define the patients anatomy
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9 valgus
o
6 varus
o
7 varus
Proximaltibial angle
Distal femoral angle
Tibiofemoral angle
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2.Plan distal femoral resection-AP Xrays
o
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More bone removed from end medial Femoral condyle
with six degree valgus Cut from a nine degree
valgus femur
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3.Plan tibia resection-AP Xray
8-10mm
o
90
90 degree tibia resection On AP Xray
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4.Plan posterior condylar resections-lateral Xray
Equal distal and posterior cuts planned
Distal cut
Posterior cut
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5.Select component size-lateral Xray
Varus kneeuse smaller condyle to Template for
component size
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6.Plan ligament releases- AP Xray
Release of contracted medial structures will
permit appropiate tensioning of the convex
lateral ligaments
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The Valgus Knee
SIX DEGREES FEMORAL RES ECTION CUTS MORE MEDIAL
CONDYLE
o
o
6
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Medial condyle
In valgus knee,template the relatively normal
medial condyle
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The Varus Knee
o
6
9mm
8mm
6 degree valgus cut Removes more bone
laterally And no more than 10mm
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Posterior resection match distal resection and
lateral condyle for templating
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SURGICAL PROCEDURE

• Best location for femoral joint placement
• Thickness of distal and posterior bone resections
  for optimum ligament balance
• Potential need for tibia bone graft
• PCL status and need for release
• Need for lateral or mediial ligament release
• Correct size femoral component required