Femoral Component Rotation John R. Moreland, M.D. Transforming Orthopedics: Advanced Outcomes and Techniques January 30-February 2,2008 Vail, 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 Brochures Early 1980’s
Radiographic Analysis of Lower Extremity Axial Alignment Moreland and Hanker JBJS 1987 25 volunteers
Angle B • Mean 92.8 degrees • S.D. 1.5 degrees • Range 90 to 96.5 degrees
Mechanisms of Failure in Total 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.