Abstract
Objective: We studied the relationship between rotation of the femoral component and patellar tracking by computed tomography (CT) and X-ray imaging before and after total knee arthroplasty.
Methods: Fifty-six primary total knee arthroplasties using the Duracon total knee system (Stryker) were carried out in 53 patients. The femoral components were implanted in 3 external rotation to the posterior condylar axis. The posterior condylar angle (PCA) and the condylar twist angle (CTA) were measured by CT before and after the operation, and patella tilt was measured using X ray and CT imaging before the operation.
Results: The average PCA before TKA was 3.86°±2.19° and the average CTA was 7.38°±2.20°. The average PCA after TKA was 0.43°±2.54° and the average CTA was 3.95°±2.63°. Patellar tilt after the operation was 1.07°±5.75° as measured by CT (0° knee flexion), 3.70°±5.91° at 30 knee flexion, 1.84°±5.51° at 60° knee flexion, and 0.39°±4.65° at 90° knee flexion. Patella tilt tended to increase after the operation in patients in whom the CTA and PCA also increased after the operation. The correlation between PCA and patella tilt was higher than that between CTA and patella tilt after the operation.
Conclusion: In TKA, it is preferable to set the femoral component parallel to the surgical epicondylar axis (SEA) to improve patellar tracking after the operation.
