Total Knee Arthroplasty in Total Knee Arthroplasty in Varus KneeVarus Knee

H.Makhmalbaf MDH.Makhmalbaf MDConsultant Orthopaedic & KneeConsultant Orthopaedic & Knee

SurgeonSurgeonGhaem Hospital Medical SchoolGhaem Hospital Medical School

The most important factor in The most important factor in maintaining satisfactory long-term maintaining satisfactory long-term

outcome in TKA is anatomic outcome in TKA is anatomic alignmentalignment

This depends significantly on This depends significantly on ligamentous balanceligamentous balance

The most favorable results are The most favorable results are observed with femorotibial angle observed with femorotibial angle

3-73-7oovalgus , valgus , the tibial component in neutral,& the tibial component in neutral,& the femoral component in 4-6the femoral component in 4-6oo

valgusvalgus

The typical patientThe typical patient

• Severe varus deformity

• Some varus alignment since childhood

• H/O medial menisectomy

• Gradually progresses

• Lateral subluxation of the tibia on the femur

ExposureExposure

• Standard medial parapatellar arthrotomy

• Resect medial meniscus

• Release deep MCL

• Resect ACL

• Externally rotate & deliver the tibia

• Remove all osteophytes

Mediolateral BalancingMediolateral 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 techniqueShift & resect technique

• 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 & resectShift & resect

• 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 Formal MCL release from the tibiafrom the tibia

• Release deep MCL

• Posteromedial capsule

• Remove osteophytes

• Release PCL

• Resect PCL & put PS knee

Distal femoral resectionDistal femoral resection

• 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 rotationFemoral 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 deficiencyTibial 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 laxityResidual lateral laxity

• 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?

summarysummary

• 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 youThank you