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

Diagram from David Hungerford

TKR BrochuresEarly 1980’s

Radiographic Analysis of Lower Extremity Axial Alignment

Moreland and HankerJBJS 1987

25 volunteers

Angle B

Mean 92.8 degrees S.D. 1.5 degrees Range 90 to 96.5 degrees

Mechanisms of Failure inTotal Knee Arthroplasty

CORR 1988

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.

Thank You