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Femoral Component Rotation
John R. Moreland, M.D.Transforming Orthopedics: Advanced Outcomes and TechniquesJanuary 30-February 2,2008Vail, Colorado
Femoral Component Rotation Measured resection using bony
landmarks Posterior femoral condyles Femoral epicondyles Whiteside’s line Scratches on femoral condyles
Gap balancing using ligament tensing in flexion John Insall
Chronology 1978-79 fellowship in London with Mr.
Michael Freeman Taught me equal posterior condyle
resection Did not look right to me Insall TKR brochures said tense
ligaments in flexion and cut parallel to the previously resected tibia
I was puzzled
External Femoral Rotation Relative to the Posterior Condyles
Less patellar dislocation/subluxation Less patellar lateral release need Better ligament balance in flexion Now all authorities recommend
unequal posterior condyle resection Should the bony landmarks or the
ligaments decide how much?
Gap Balancing Technique for Femoral Component Rotation
This is the Insall way of achieving external rotation of the femoral component relative to posterior condyles.
Insall told me he would never internally rotate the femoral component relative to the posterior condyles even if the ligaments told him to do so.
We know ligaments contract and give wrong information in extension and contracted ligaments can also give wrong information in flexion.
If contracted ligaments can be “balanced”, how does the surgeon judge when enough balancing is done other than if the ligaments after balancing give proper external rotation of the femoral component relative to bony landmarks?
Gap balancing is really using bony landmarks as the gold standard
Measured Resection Technique for Femoral Component Rotation Uses bony landmarks
0 to 6 (mean 3) degrees of external rotation relative to the posterior femoral condyles
Parallel to the femoral epicondyles Perpendicular to Whiteside’s line Perpendicular to scratches on the femoral condyles Use all four bony landmarks
Using bony landmarks for femoral component rotation is currently the distinct majority view Informal poll at The Knee Society summer meeting. Informal polls at other meetings I have attended.