Transcript Total Knee Arthroplasty in Varus Knee

Total Knee Arthroplasty in
Varus Knee
H.Makhmalbaf MD
Consultant Orthopaedic & Knee
Surgeon
Ghaem Hospital Medical School
The most important factor in
maintaining satisfactory long-term
outcome in TKA is anatomic
alignment
This depends significantly on
ligamentous balance
The most favorable results are
observed with femorotibial angle
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3-7 valgus ,
the tibial component in neutral,&
the femoral component in 4-6o
valgus
The typical patient
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Severe varus deformity
Some varus alignment since childhood
H/O medial menisectomy
Gradually progresses
Lateral subluxation of the tibia on the
femur
Exposure
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Standard medial parapatellar arthrotomy
Resect medial meniscus
Release deep MCL
Resect ACL
Externally rotate & deliver the tibia
Remove all osteophytes
Mediolateral Balancing
• Ligament balance in flexion & extention
are interrelated (unlike valgus knee)
• In a varus knee , the knee should be
balanced in extention first then in flexion
Shift & resect technique
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Tibia is delivered in front of the tibia
Initial conservative tibial resection
Based on the intact lateral side
10mm lateral resection
Angle of resection is perpendicular to the
long axis of the tibia & 3-5o posterior slope
• Choose tibia one size smaller
Shift & resect
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Choose tibia one size smaller &
Shifted laterally to the edge of tibia
Align tibial rotation with tibial tubercle
Outline the nucapped portion of tibia
Free the MCL from bone
Resect bone perpedicular
Formal MCL release
from the tibia
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Release deep MCL
Posteromedial capsule
Remove osteophytes
Release PCL
Resect PCL & put PS knee
Distal femoral resection
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Pre-op X-ray
Varus in the femoral shaft ?
Usually 5-7deg.cut
More resection of medial fem. condyle
The amount of resection depends on the
thickness of metallic femoral component
Femoral component rotation
• Establish a balanced, symmetric flexion
gap to maximize flex. Stability
• In varus knee balance in ext.1st
• Use the Whiteside line or trans epi.
• 30 external rotation
• Then posterior condyles in flexion
Tibial bone stock deficiency
• Medial tibial plateau is always deficient in
varus knee
• Resect enough bone not too much
• Bone graft
• Cement & screws
• Metal wedges
• Allograft
Residual lateral laxity
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How much laxity is acceptable
The bony alignment should not be in varus
The lateral should not gap open on the tab
Correct significant laxity
More medial release
Fibula head advancement?
summary
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Tibia is responsible for varus
Release MCL, remove osteopytes
Bone resection, undersize, sift
Balance flexion gap
PCL retention in severe varus?
Release PCL ?
Accept some residual laxity if
Fill bony defects in tibia
Thank you